Home Forums Hunting & Shooting Express Rifles and Big Bores Only 450 G&A Short

I’m looking for an intermediate 0.458” cartridge between the 458 Win Mag and the 450 Rigby Rimless, based on the minimally altered 404 Jeffery case and a max COAL length of 3.6”.

Made up a dummy on a slightly shortened 404 J case but looks like the cartridge exists as a wildcat already. So I’m thinking about building a 460 G&A Short on a Winchester Model 70 Classic. I know that the parent case is the 404 Jeffery but I’ve searched for authoritative data on case length, cartridge overall length and ballistic performance (MV Range) but haven’t found it.

Other than an old G&A article by Tom Siatos describing the original 460 G&A in general terms, I haven’t turned up useful data.

Any leads on credible info on the data identified would be greatly appreciated to base a chamber reamer on.

I have the poop on the .460 G&A from 1973, 1983, 1989 and 1994 pubs.
Includes the cartridge drawing and some handloading info.
Also have two reamer drawings, one from Clymer
and the other from Dave Manson with "GUNS & AMMO" specified as the customer for the reamer.
I'll get it up when I get done with some chores Wife has got me doing.
This stuff is right up my alley, since I am able to pontificate to no end on .458-caliber rifles, haha.

Thanks, RC. That’s exactly what I’m looking for. I’ve had Dave Manson make wildcat reamers for me before and I’m planning on having him do this one for me as well. Cheers!

I reckon the .450 G&A Short Magnum (2.5" case) is simply a .460 G&A that is shortened in case body, below the shoulder, by 0.300".
Same neck and shoulder.
Could do it with same reamer inserted 0.3" shorter than the .460 G&A, using appropriate headspace gage.
Just make sure the .450 G&A Short Mag dies resize the brass to match the chamber.
However if you rechamber a .458 WinMag with a .450 G&A reamer, you might as well give it a .458 WinMag throat.
It is going to have one anyway unless you cut the barrel threads and set it back.
With a virgin barrel, you can have any throat you want.
I would want the .458 WinMag throat, then I could do practically anything with it that the short-throated .460 G&A could do.
Almost as good as the .458 WinMag loaded to 3.600" COL,
which can absolutely beat a SAAMI .458 Lott.

All I have is boiled down into the images below.
First from the 1983 BIG BORE book from G&A by Jack Lott:







The two .460 G&A reamers here are identical except the Manson reamer has a slightly shorter and narrower parallel-sided-free-bore,
and a more gradual leade: 0.459" diam., 0.150" long PSFB, 1.5-degree leade hemi-angle.
Clymer throat: 0.460" diam., 0.200" long PSFB, 2.5-degree leade hemi-angle.

Since the Model 70 will handle the 375HH and 458Lott, seems like a full size 460G&A would also fit. Or maybe not if receiver is machined different at the factory and the OP is not starting with a H&H length bolt throw? If possible the longer case will allow for lower pressure to get the same performance as the short version or go a little faster if wanted.

Since the 450 Rigby was mentioned my understanding the claim to fame for that round was performance at low pressure. The hunters native to Africa seem to value that quite a lot. Or so I read from those who like the Rigby. I am just in this for the fun with a kind of big bore fetish.

I do remember reading about both back in the good old days when I had a G&A subscription. Today everybody loves the 458wm. Back in those days there were a lot of unhappy campers.

The Model 70 Classic and later Winchesters M70s will make great 404 Jeffery rifles, I have one made from a .300 RUM re-barreled.
No doubt they would make a great .460 G&A or .450 G&A Short Magnum.
Either one will do fine.

After trying
.460 WBY X 2
.450 Dakota X 1
.458/.338 Lapua Magnum X 2
.450 Barnes Supreme X 1
.458 Lott X 2
.458/.416 Ruger X 1
.458 B&M X 1
.458 Winchester Magnum X A BAKER'S DOZEN ...

I choose the .458 WinMag, happily ever after.

RC, exactly the info I needed.

My original intent was to rechamber a Ruger tang safety M-77 458 Win Mag to 450 G&A Short. However I’ve reconsidered and decided to rebarrel an infrequently used Win M-70 SG Classic 300 Win Mag to 458 Win Mag and rechamber to the full length 460 G&A. I’ll use the Manson reamer as I’ve used several of his reamers in the past. He’s easy to work with, fast and makes a great product.

I have experience, rifles and components in 404 Jeffery (P-64 Win 70) and 450 Rigby (Ruger RSM 416 Rigby rebored) so the project seems fairly straightforward. BTW the 404 J cases fit the unaltered bolt faces in both the Ruger 458 Win Mag and the win M-70 300 Win Mag. Removing the magazine block and altering the bolt stop in the 300 should allow the 3.6” bolt throw.

I’ve found that the 404 J with CEB BBW #13 400 grain solids at 2500 FPS MV shoots through an elephant broadside, so it’s a perfectly suitable rifle for African big game. However, a 458 caliber rifle on the 404 J case seems the best solution to this situation. Compared to my Ruger 450 Rigby the bolt throw will be a bit shorter/faster and the rifle handier (planned new 458 barrel will be 23” contour and brand TBD) and stock proportions more to my liking. I know only a rifle loony would appreciate these fine points, but there you go. It’s wildcat fever in full bloom.

Probably will sell the TS 458 Win Mag Ruger as I’m reluctant now to alter it. We’ll see the ultimate fate of the RSM 450 Rigby once the 460 G&A is completed.

Thanks again for the info, have work to do.

FWIW, Good choice. I probably dont need to tell you this as I think you got 10x more experience than me on these projects. The industry makes pull through reamers. I did a garand with one becasue I could not access the chamber from the rear. It worked real slick. the bolt follows the reamer and when the bolt falls - done. Or, You can stop just a nit before the bolt is all way down to cut a min chamber. Not for DG, but; just saying there is that flexibility with the visual feedback.

If I had a Ruger RSM in 450, I would be thinking long and hard about letting that one go.

fourbore,

Thanks for the info on the pull through reamer. I am not familiar with that technique. Any leads on manufacturers who would cut one in a wildcat reamer?

You’re right about the 450 RSM. That rifle is now just the right weight for the cartridge with a 500 grain bullet at 2350. The original stock was somewhat blocky for my taste so I had RJ Renner reconfigure it to his Rigby style. I like the way it handles now much better.

For the type of hunting I believe I have left to do large mediums and large bores are likely to see more use. So the RSM fits in that plan.

I got that reamer from Manson.

Thanks

It comes in 3 parts. The reamer, a long rod and a t handle. First time expense on the last two. I found a tap wrench worked fine as the T handle.

As an after thought, 460G&A might be asking a lot. Asking is free

I called Loon Lake precision yesterday and found out they will make the 460 G&A to the original specs. I should receive it in the next 3-4 months.

Unfortunately I was told that due to the reamer dimensions they can’t make it as a pull through. I’ll need to get a set of headspace gauges next.

Planning to test a couple of magazine followers I have in the M-70 action I’m planning to use. Been looking at a few barrels in 458 Win Mag as a starting point to rechamber. I’ll need to see if I can get one without the cartridge stamp.

Next step is to run a 404 Basic case through a backed out 404 J full length die and expand the neck to 458 in the 450 Rigby die. Need to get an idea of seating depth with the 450 & 500 grain CEB BBW #13s to keep COAL at 3.6” max.

Starting to be an interesting project.

Allow me to play devil's advocate.
You will have a bit of remnant .458 WinMag throat if you re-chamber a .458 WinMag barrel,
even with the .460 G&A reamer from Manson, unless you set the barrel back, and turn a 24" barrel into a shorter barrel.
Not a bad thing, either way.

The .300 RUM follower and windowed box that came in the factory M70 rifles should be the cat's meow for 3 down in the box.

Or try the Sunny Hill drop bottom metal for M70 .375 H&H and experiment with the followers and feed job.

I see the .460 G&A as a welcome way to re-barrel or rebore an unwanted .375/404 Jeffery or .410/404 Jeffery
to make a more interesting rifle.
The .458 is tops.

RC,

After looking over the 460 G&A specs and drawings I’m having a hard time understanding how rechambering a standard 458 Win Mag barrel will leave part of the original throat. Please explain so I might better understand. 458 Win Mag case is 2.5” COAL is 3.34” both much shorter than 460 G&A specs.

As a matter of fact, it seems to make sense to start with a 458 Lott chambered barrel to rechamber to 460 G&A. Both cases are 2.8” long and COAL is 3.6”. What do you see as a problem with that plan?

BTW, I’m planning on a 23” barrel, probably a Douglas with a target weight of +/- 4 lbs. Target rifle weight is 10-10 1/2 lbs.

I wouldn't go lighter than 10 1/2 pounds including scope if you plan on running a 500 grain projectile at 2300 fps or above. If you were using the .450 G & A Short running a 500 grain projectile at 2200 fps then I'd aim for no less than 10lbs including scope.

The 458 Win mag has a much longer throat than does the 458 Lott

My current 450 Rigby Rimless is 10 lbs 10 oz, iron sights no scope. Controllable with 500 gn bullets at 2350-2425 fps for follow ups. I wouldn’t make it any lighter.

The 460 G&A I’m working on now should come in about 10 1/2 lbs - no less - planning a 500 gn bullet at about 2300 fps. The main variable to achieve that weight will be the barrel contour. Plan to call Douglas to get an accurate weight of one of their 23” barrels chambered in 458 Lott and adjust the countour based on that. A few ounces will be added by peep sight, barrel band front swivel, NECG Masterpiece Banded ramp FS. Haven’t decided yet whether to keep factory bottom metal with a different follower, spring, magazine box. That decision may add a few ounces as well.

I want to make sure that the rifle retains balance when mounted and aimed. That’s critical IME for first and follow up shots.

Yes, indeed.

Here is a Manson reamer for .458 Lott (SAAMI)
and a Clymer reamer for .458 Winchester Magnum (SAAMI), side by side:





Here is a drawing showing that the throat of a SAAMI .458 Lott lives entirely inside the throat of a SAAMI .458 WinMag:



The Manson 460 G&A throat is living a little bit more so inside the throat of the .458 WM.
Infact, you will have an itty-bitty length of the SAAMI .458 Lott throat left if you rechamber one to .460 G&A without setting the barrel back an itty-bitty bit.

Some Winchester M70 rifles that could be re-worked into 460 G&A:

RC,

My starting point is a Win M-70 Classic very similar to your top photo, except it’s a straight comb SG, which I prefer for both aesthetic and functional reasons. I don’t plan on a scope and plan on a 23” barrel - my personal idiosyncrasy on my rifles. So it looks like a Douglas #5 contour may well do the trick.

I have the RUM follower & 375 H&H Mag spring OTW now. The rear Mag block seems an easy removal and may just replace the bolt stop with a 375 H&H bolt stop - we’ll see when I get to that. I’ll need to look into the RUM windowed Mag box and the geometry of a factory RUM box in a current rifle, especially the feed rails. Haven’t tested the 404J in that rifle yet for feeding - next step.

I will probably add a second cross bolt to the stock and a Pachmayr Decelerator or Limbsaver pad. After the barrel is installed, I’ll look at the weight and balance and decide whether a bit of lead might be needed to achieve target weight. Placement will depend on the balance at that point.

Thanks for the details on the chambers and reamers. I’m now convinced that starting out with a chambered 458 Lott barrel is the most straight forward way to go, using just the Manson 460 G&A finishing reamer. I need to look at the feasibility of using some of the dies I currently have (404J, 450 Rigby) vs a 460 G&A custom body die. Will decide this once I have some fired cases from the new chamber.

This project is getting to be more interesting all the time. Hopefully will get a chance to try out the finished product in 2024. The conundrum will be whether to use the 460 G&A in the field as primary with the 450 Rigby as backup or the reverse. Testing will tell.

Now if you were to build a short, light .450 using a standard length action, 22" barrel and either the .450 Howell or .450 G & A Short, you could use the .450 Rigby in the open areas and the shorter, lighter, better handling rifle in the thick brush or as a back-up.

Interesting thought. Although I’m not as experienced as an elephant hunter as others on these forums, I’ve done a few hunts. I haven’t found a place yet where a hunter could get a good shot at an elephant that an inch of barrel length would prevent it.

If it’s that thick the chances of not stumbling on an elephant on the way into the herd to get a good look are pretty slim. Ran into just such a situation a couple of weeks ago. More likely hunting small bull herds. If the rifle is well balanced carrying a 10-10 1/2 lb rifle over the shoulder while walking hasn’t become an issue so far.

This may be an issue in other places I haven’t been to yet and probably won’t. YMMV

Yup, 23" barrel is as short and handy as I like on a .458 bolt action.
Anyone not a dwarf should do well with 23" barrel.
My ancestors survived running around with 44" barrels.
You want to do more poking than swinging when you get into the brush.

#5 sporter contour will work great on any .458 bolt action rifle, ideal.
#4 sporter contour and 23" barrel is minimum, if a featherweight is the goal, requires 2-pound stock.

Yup, you can easily add a pound with well-balanced lead and epoxy and/or mercury tubes
in butt and forearm of stock.
Phil Shoemaker made his Old Ugly gain a pound by doing that.

Until you get proper dies, if you can shorten a .450 Rigby die by about 0.060" ground off at the base
that would be a dandy neck sizer,
since the .450 Rigby has a 0.500"-long neck and the 460 G&A has a .458"-long neck,
and the Neck-1 location at shoulder juncture would line up pretty easily.

2.3998" - 2.3415" = 0.0583" (see cartridge drawings below, brass maximums)
Grind off base of die and adjust die upward to fine tune jam fit in chamber.

Thus, neck-sizing of brass, after fire forming,
using a reversed bullet loaded with base into the rifling, to blow out the 404 shoulder to 460 G&A.

Grinding that tiny amount off the base of your .450 Rigby FL die won't hurt it for future use, if you have a headspace gage for the .450 Rigby.
Obviously nicer to have a spare to do the shortening on, at base of die.





And for redeeming social value, the .450 Howell is very like the .450 G&A Short Magnum with sharper shoulder:



And the .450 Dakota: Thicker in neck wall and has wider shoulder and narrower base than the .450 Rigby.
The .450 Dakota is more like a 460 WBY with belt turned off and angulated shoulder.
At the time it was designed, before the .450 Rigby, .416 Rigby brass was rare as hen's teeth,
but 460 WBY brass was easy to come by:

Excellent points, RC. I’ve used the 460 Wby - 6% algorithm for equivalent 450 Rigby Rimless loads. That’s 100-104 gns RL-17 behind a 500 gn Barnes Banded Solid or 500 gun CEB BBW #13 bullets. IME Barnes Banded Solid or CEB BBW #13 bullets produce very similar MVs at equal COAL and powder charges.

I’ll consider shortening my 450 Rigby FL sizing die.

Just removed the magazine spacer in the Win M-70 today and confirmed the 460 G&A dummy at COAL 3.6” COAL fits well with a 375 H&H follower. We’ll see how the RUM follower fits when it gets here.

Yes, and you will have a headspace gage for the .460 G&A.
Use that in your shortened .450 Rigby die to set the headspace when neck-sizing your fire-formed .460 G&A brass.
Foolproof.
I have done such with a .264/.375 Ruger using a Manson headspace gage for my pet wildcat,
called the .264 Ripmore or 6.5 Ripmoor depending on company present.

If you get the .375 H&H boltstop/ejector in there, it will be timed to eject 3.6" loaded cartridges,
loaded ammo bullet nose will clear,
you will not have to do anything to shorten the rear bridge or lengthen the ejection port.

If you find a source for .375 H&H M-70 boltstop/ejector, let me know.
I could find a use for some of those.
Last time I filed and stoned one myself, to get a .270 WCF M70 Classic action to eject .400 Whelen 3.6" ammo properly.
File a little, re-install, try ... uninstall, file, install, try ... uninstall, file, try ... Success !
I'd rather buy them ready-made too !

RC,

Midwest Gun Works is where I found the Win M-70 CRF RUM mag follower & 375 H&H length ejector and bolt stop. Have them on the workbench but haven’t installed them yet.

Doing some work on the RSM 450 Rigby which needs to be finished before tackling the 460 G&A project full time.

Thanks for that, ordered a couple of spares for future use:



Appears they are sold out of this, but you can cut windows in the top of your box if you need more space:



I see they still have these:



And surely your spring is like this:



Beware of this abomination:

Unfortunately my mag spring is the abominable space killer!! Haven’t been able to locate a suitable full length replacement yet so I’ll need to scrounge through my stuff and see what I find. So far the closest alternative may be a magnum Mauser spring but I’ll need to look at dimensions before deciding.

Assembled the donor action with the RUM follower, mag box with the rear block removed and can fit 3 404J-cased dummies - including one with a 0.458” CEB BBW #13 500 gn bullet. They fit and feed though not smoothly yet because of the stock bolt stop. The bolt face and extractor control the case normally, once the cartridge rises. We’ll see how it works with the bolt stop replaced with the 375 H&H part. Probably will need some tweaking of the feed ramp eventually.

Small steps along the way but headed generally in the right direction, it seems.

I know you said at the beginning that you are looking for an intermediate between the 458WM and the 450 Rigby, but you didn't say why. I found this thread very interesting and was just wondering if you are doing this purely for the experience/entertainment or if it will fill a perceived role that the others do not. I am a long-time fan of the 460G&A, but have recently come to appreciate the 458WM even more, and am always trying to learn more.

SLGPT,

The purpose of the rifle I'm building is for hunting DG. I have used a 500 NE 3" in this role, but decided to give up DRs and use a bolt rifle instead, as I have more experience with those. That was the purpose of the Ruger RSM 450 Rigby but ran into a last minute problem and used a 404 Jeffery instead for this year's hunt.

The 404 Jeffery did very well, but I still prefer a 45 caliber DGR. Hence the idea of the G&A. As is the case with most wildcatting plans, there's no free lunch, so it's likely I'll wind up with a 10 1/2 pound rifle to make the recoil reasonable for follow up shots. In the end it's likely the only advantage to the 460 G&A will be the slightly shorter Winchester LA compared to the RSM.

Maybe more rifle loony flimsy thinking, but there it is. I'm hoping the rifle will see use in the field in 2024.

I certainly understand rifle loony thinking! I too like the slightly shorter action aspect.

What happened to the 450Rigby, if you don't mind me asking?

Inconsistent feeding. On its way to repair.

Thank you. Would love to see pics if/when able.

At the stage of getting things together. Spoke with Douglas Barrels today. They will fit a 5A 23” barrel to my Win M-70 action and use my Manson 460 G&A reamer - when it’s ready - to chamber the barrel. Big step forward.

Will need to wait for the barreled action to return before deciding about the current SG stock vs something different. All dependent on the barrel taper.

Your walnut will work fine, barrel channel sanded and bedded with epoxy.
So will a Bell & Carlson "Medalist" type stock.
You will likely want a secondary recoil lug on the barrel with walnut.
No need for that with the B&C stock having full bedding block.
B&C will handle a No. 5 Sporter.
I have sanded them out to fit No. 6 sporter from Pac-Nor,
and even cut into the aluminum endoskeleton in the forend to bed a secondary recoil lug.
Ditto a McMillan claimed to be good for up to No. 5 sporter,
I have gone even bigger-barreled with McMillan.

I intend to push the walnut option with a slim forend and any weight needed to hit target added in lead at buttstock and possibly forend to maintain balance. However I'll consider a synthetic stock if the current SG stock channel modification doesn't work.

I've looked at the Bansner website as I have a couple of the old stocks and they work well. I've not yet seriously inquired about these but will consider this option if needed. Based on the specs I've seen so far, added weight would be needed.

I'm aiming for a classical rifle with CM blued barrel and walnut stock as it seems most suited for its purpose - pursuit of DG. After all as JOC said, this is all about fun and games, at least when reliable DGRs are involved.

I noted how the barrel recoilo lug was added on my 404 J and will plan for that option on this rifle. High strength silver solder should work.

As usual in the wildcat game, it's been interesting pushing this project forward. I received the 460G&A reamer and headspace gauge from Dave Manson yesterday. Feels like a big step forward.

I spoke with a well known GS today who specializes in building working professional DGRs on Win M-70 Classic actions. He's agreed to take on the task of turning a Win M-70 Classic SG which left the factory as a 300 WM into a 460 G&A properly reliable DGR. Another great step forward! Estimated build time 4-6 months, so in time for a summer Zim hunt. I've witnessed one of these unfailingly reliable rifles in 458 Win Mag in the hands of my Zim PH on my last 2 hunts.

Ordered a Douglas #5 sporter contour finished, turned, polished 0.458" 1:14" twist barrel today. I was told 4-6 weeks delivery. Threading, chambering and bluing will be done by the GS building the rifle.

The next challenge is finding a sizing die in 460G&A. Both RCBS and Redding told me today they are out of the custom die wildcat business til at least next year. Timing won't work. I've got calls out to a couple of smaller outfits which will probably make the dies - fingers crossed over the last couple of days until I get a commitment on the dies. I didn't anticipate this would be the most challenging step, but it's beginning to seem so.

Unless the dies don't work out, I am now starting to believe that the 460G&A will become a reality and will be in the gun case on the way to Bulawayo next summer.

BTW the build, despite the title, is a 460G&A.

Wildcatter264, have you looked at CH4D for your .460 G&A dies?

elkhunternm

Spoke with them yesterday. They have 2 sets in stock but they couldn't tell if they are specked to the Manson reamer I have. The Clymer version is a bit different so I sent them the spec diagram today and waiting for a response. If they needed to make it from scratch their lead time is 18-24 months, with a 37 page backlog of orders! Obviously they are not seriously in the game.

I've also inquired of Whidden Arms in GA - don't know their work or wait times, waiting for a response.

As a backup I spoke to the Manson's shop today and they can make me a resizer reamer based on the chambering reamer and I can have a blank die reamed to 460G&A. I know I have a die blank somewhere in the shop intended for a 35/284 but will probably use it for this project instead.

I've resolved I'm going to see this through to the end & use it in the summer.

I'm convinced that as big a hammer my 404J has proven to be, a 458 caliber bullet at 2350 is a bigger hammer!!

Cheers!!

Sir Ron,

After reviewing the prints and description of the Manson vs. Clymer reamers it’s clear that there would be a difference in the rifle chambers cut with one vs the other. But only in the throat & leade dimensions, not in the case dimensions.

However, the FL sizing die needed would seem to be the same regardless of which chamber the cartridges were fired in. Although loads required for equal MVs would probably be slightly different due to the effect of throat length ane diameter as well as leade angle on chamber pressures, headspace and fired case diameters shouldn’t vary, given equal PSI.

This will probably simplify acquisition of resizing die, if it were cut with a resizing spec reamer based on the original 460G&A reamer dimension.

Do you think these are valid asumptions?

Yes, reloading dies should be same for both
chamber reamers.

A friend has a stainless synthetic Model 70 Classic in 300 RUM that he was going to use for a 404 Jeffery build, but has changed his mind. If anyone wants to pursue a conversion project, let me know and I'll put you in touch.

👍

Sent you a PM

Just heard from CH4D today. Fortunately one of the two 460 G&A dies they have in stock matches the chamber reamer I have from Dave Manson. Should be in hand this week. The other die may be for a rimmed (?) version.

Also seems the barrel from Douglas will be delivered today. So far have caught some very lucky breaks. This may come together on time yet.

Formed the first 5 460 G&A cases easily today in the CH4D sizing die with one pass using 404 Jeffery basic cases. Set headspace on these cases to the dimension of the Mason go gauge. The formed cases required trimming of almost almost 0.15” of the neck to achieve the max COL of 2.800”. They’ll serve as the basis for dummy rounds for the GS building the rifle to ensure 100% function as a DGR.

Moving the shoulder forward and decreasing the taper, compared to the parent 404 J case, was obviously a very good idea. Given that the 500 grain 0.458” monolithic solids are longer than the 400 grain 0.423” bullets, the taper change and relocating the shoulder forward prevent loss of powder capacity. Although I’ve not measured the capacity I anticipate that these changes may have increased the capacity slightly. It’s also obvious that the 3.6” COAL, which allows building this cartridge in a standard Win M-70 length action does not maximize the newly gained powder capacity.

Because I have a 450 Rigby DGR I’m having an opportunity to compare it to the 460 G&A with respect to design of the 2 cartridges. If the 460 G&A were built on a true magnum length action, such as the Ruger RSM or one of the magnum Mausers, a COAL of 3.720” could be achieved. Loading a 500 grain monolithic bullet (Barnes, CEB BBW #13) would preserve the entire powder capacity of the 460 case, with the base of these bullets flush with the neck-shoulder junction. Of course, the whole rationale of the G&A cartridge is to provide similar performance to the 450 Rigby or Dakota with less powder, albeit at a higher chamber pressure, while allowing building it in any action that allows 3.6” COAL (ie, 375H&H length) cartridges. Slighter shorter bolt throw (probably insignificant functionally) but greater selection of actions (much more important).

I’ve been documenting the process so far and will post the pics at some point, once the rifle is ready and load development is underway.

Very interesting, thanks for sharing.
My .458/.338 Lapua Mag with 2.7" case length has about identical case capacity to your longer and skinnier .460 G&A.
I will be able to use any load data you develop, so please do pass along any loads you find particularly agreeable.
As to COL limits caused by throat length and magazine length,
I understand your pain.

I do not suffer from it myself, however.
My .458/.338 LM has a .458 WinMag throat and is built on a CZ 550 Magnum.
Can be loaded to 3.8" COL in the CZ with +3.8" mag box.
Going from 3.6" COL to 3.8" COL adds about 8.3 grains of H20 net water capacity.
That is 4.166 grains of water for each 0.1" length of shallower seating, with a .458-caliber bullet.

Why is it that so many folks cling to their tight throats ?
I am sold on the .458 WinMag throat after thousands of rounds of handloads tested in it.
The 460 Weatherby Mag throat is also way long, but of tighter diameter.
I used to shoot cloverleaf groups with that throat at 100 yards also.

Anyway, get some 404-gr Shock Hammer bullets and use them at 2500-2600 MV in your .460 G&A.
You will be able to do that at COL of 3.580" with no re-throating:
2.800" case + 0.780" nose projection, seated deep.
You will need no other bullet unless the game is heavier and thicker-skinned than a ton of cape buffalo.
But, truth be told, that load would probably be sufficient for elephant,
though an FN solid would be cricket.

Thanks for the advice, Sir Ron. I’ll post load data once the rifle is completed and we enter that phase. Hopefully mid-Spring 2023. The components will ship to the GS who’ll build the DGR tomorrow. I’ve seen one of his rifles at work in Zim and decided he was the right guy to build this one for me. Unpretentious, all business and reliable.

As to bullets, I’ve been looking at the Hammer’s website today. I was surprised they have so shamelessly neglected those of us disciples of the 404, so wrote them a brief missive - how about a 400 grain 0.423” bullet?

For my upcoming hunt in Zim I’ll use CEB BBW#13s. I’ve used them in the 500 NE 3” and 404J last year, with great success. Though my target is more than a ton of buff and I believe you may be right about the Hammers on pachyderms, I’ll stick with the monolithic solid, at least on this trip.

I’ll order some 0.458” Hammers and test them at some point, as I’m planning on putting together a 458WM No. 1 from components in hand and will use the 458WM+ data you’ve developed in that rifle. My current 458WM Ruger M-77 bolt’s magazine won’t allow longer COALs.

After a shipping incident by USPS resulted in a broken stock requiring a return trip to the GS who built the rifle, the 460 G&A is finally home! The replacement Super Grade stock has better figure than the original one and is now fully bedded once again, including the added barrel recoil lug and crossbolt . The build came in at 9 1/2 lbs loaded, so most likely another 8 oz lead will go into the buttstock next week, after I shoot the initial loads.

Planning to test the rifle with the originally published loads, H-4064 with a Hornady 500 grain DGS. Will work up to as close to 90 grains as possible, depending on recoil and MV. Will likely try a couple of other similar burn rate powders also. The feeding, extraction and ejection with dummies loaded with 500 grain CEB BBW #13 FPs is flawless, as anticipated. The newly fabricated box holds 4 cartridges with a COAL 3.64”.

Unless some unanticipated problem arises during load testing, this will likely be the primary rifle for Zim this summer. It is trim, balances well and fits quite well, with the NECG rear peep and white line post FS aligning quickly and reproducibly. The Ruger RSM 450 Rigby Rimless will arrive in a couple of days, so a test with known loads will be in order.

May well be that after a long respite, the 460 G&A will experience a brief African rebirth. The more things change, the more they remain the same.

Now have all 3 heavy rifles which are suitable for the upcoming safari to Zim in a couple of months. The middle rifle is the Ruger RSM 450 Rigby Rimless for which I’ve already developed loads for the CEB BBW#13 500 grain solid at MVs up to 2400 FPS. It had some feeding problems which were corrected by Mark Cromwell at NECG. Feeds more smoothly than ever and holds 3 in the magazine. A bit heavy at 11 lbs loaded which is ideal for the level of recoil. It is very well balanced and lines up the sights naturally when shouldered. As soon as I sight it in with the new NECG rear peep, this one is ready.

The top rifle is the Ruger Hawkeye 458 WM I’ve described in the 458 WM thread. A bit more load development with the CEB BBW#13 450 grain solid propelled by AA-2230 and Varget should get MV close to 2250 FPS. This rifle will definitely make the trip.

The bottom rifle is the new Win M-70 Classic built in 460 G&A by Gene Simillion. Holds 4 in the newly built box, feeds smoothly with dummies with the 500 grain CEB. I’ll start load development using H-4064, RL-15, and BL-C(2). Currently this rifle weighs 9.5 lbs loaded, but with realistic prospects of reaching 2350 FPS with 500 grain bullet, it needs a bit more weight, so I’m planning to add 1/2 lb lead in the buttstock. The rifle has turned out to be what I was looking for from Gene - a working DGR which will work every time, without drama. The work is flawless and the rifle unpretentious, though the replacement buttstock grain is much better than I anticipated. This is the rifle I hope works well when I develop loads, as balance and anticipated weight should make it sleek and totally dependable.

Will report after the next range session.

Good work.
Down sized to display in the scroll:



2350 fps with the 450-gr CEB Brass FN Safari Solid is a nice load for any 24"-barreled .458 WinMag:



Are you using Redding dies on the .458 WinMag ?
FL sizing with those resulted in wasp-waisted loads for me.
Using RCBS FL sizer does not squeeze down the .458 WM brass as much and makes a prettier load.

RC,

I’m using RCBS dies for the 458 WM. The cases you see are cutoff 458 Lotts. I didn’t internally ream them so that results in thicker walls.

They’re from an old 458 Lott RSM that has gone down memory lane but it’s what I had most when I made these dummies.

I now have proper new 458 WM cases and will use those for sighting in and the trip.

Good catch!!

Brief range report of the first firing of the 460 G&A Win M-70. The rifle was built by Gene Simillion.

Started out with the original IMR-4064 loads developed by Tom Siatos. Fired Barnes 500 grain monolithic solids with 84.0 grains (MV = 2332 fps), 86.0 grains (MV = 2375 fps). I didn’t fire the 88.0 grain load having passed target MV of 2350 with the 86 grain load.

Also fired RL-15 loads with the 500 grain Barnes at 84.0 grains (MV = 2214 fps) and 88.0 grains (MV = 2256 fps). Will probably load 90 and 92 grains with the CEB BBW #13 500 grain monolithic solid for the next session as this is a slower powder than the 4064 and there’s sufficient room in the case without much compression.

Last batch was loaded with BL-(C)2 with the same 500 grain Barnes solid at 84.0 grains (MV = 2272 fps) and 88.0 grains (MV = 2343 fps). Will also load 89 grains with the CEB 500 grain solid for the next session.

All shooting was at 25 yds with peep sight and MVs are measured at about 10 yds uncorrected. This will be the second rifle for the Zim safari with the Ruger Hawkeye 458 WM described in the 458 thread and also fired today.

The rifle is very accurate, comfortable recoil - even seated at the bench - so I’ve decided to not add any weight as I had planned.

Thanks for sharing.
Good data to use in my .458 Ted Williams Thumper (.458/.338 Lapua Magnum Unimproved).
Very similar in case capacity to your .460 G&A.

Got to the range today to try a new load in the Win M-70 Classic 460 G&A. Given current powder supply conditions, I decided to try a powder other than IMR-4064, because I have a small supply of that powderleft and it seems to be out of stock just about everywhere.

Looking at the powder burn rate charts, I realized that RL-15 is a bit slower that IMR-4064 and my prior data showed that an 86 grain load produces a mid-2200 fps MV. Given that the 460 G&A case has a volume to the neck-shoulder junction (measured wit BL-(C) 2) of 100 grains, I loaded the CEB BBW #13 500 grain FPSS with 90 grains of RL-15 - I have an adequate supply of this powder - and fired 6 cartridges with it today. MV corrected at 8 yds is 2410 FPS with SD = 4, max spread = 11 FPS KE = 6449. The RL-15 experiment seems to be a success, because it produces excellent MV with markedly less compression than IMR-4064 due to the small granule size.

Here’s the target at 25 yds, with successive adjustments to zero



I also wanted to determine the sighting system to use. The Leupold 1-4x25 produced good groups but the rings wouldn’t hold it in recoil. I’m not totally sold on using magnified optics for elephants in herds.

The Holosun 530 produces an excellent sight picture with very comfortable cheek weld. However, the scope base loosened under recoil despite torque screws fully tightened. I believe the height of the QD mount provided wit the 530 results in significant angular velocity. I changed out the factory high mount for an aftermarket QD lever mount and will try that next week, with the torx screws Loctited in place. I’m hoping to avoid having to epoxy the base to the receiver but that may be the next step. I’ll also ry the NECG peep in a forward receiver ring base.

Once the sighting system is finalized, both the DGRs will be ready. Tempus fugit now.

Hey hey hey, RL-15 was my pick for the .458/.338 Lapua Thumper. Excellent with 500-grainers and 350-grainers.

The only time I don't 8x40 and JB-Weld scope bases on .458s
is when the rifle has integral bases
or with a Near Mfg. Picatinny having a recoil stop on the bottom of the rail.

Considering both measures. For the next session switched over to Warne lever actuated QD steel rings and Loctite on the base torx screws. I don’t have a competent GS within easy driving distance and don’t want to send the rifle away at this late stage. We’ll see what solution I can rustle up.

Since you mentioned the Thunper, I happened to run across a box of 338 Lapua brass in the shop yesterday and got this photo, just for perspective on ‘other’ 458 wannabes.




450 Rigby on the left, 460 G&A in the center and an unaltered 338 Lapua on the right.

Spent time time stamping the first 10 cases as “460 G&A” yesterday. Will post some pics of the stamped bases when I finish a few more. Need to turn out 30 stamped, formed cases to load cartridges which will pass muster upon arrival in Zim.

Excellent to get any tips on headstamping blanks.
Do you have your own bunter and press or some other method?

Near identical case capacity to 460 G&A is the .458 /.338 LM:



My favorite load in the Thumper was RL-15 and 450-gr North Fork softs and solids at just over 2600 fps.
Uniform and accurate.
That was in a 22" barrel, 1:12" twist, throated like a .458 WM.

I have a 1 ton press but I’m stamping by hand instead as I’m getting better results. I built a jig but it didn’t work well. I don’t have enough time to start over so will need to redesign and build another when I get back.

Here are a few marked cases. Not perfect but sufficiently clear they match the stamp on the barrel

Excellent work.
Dave Estergaard used a hydraulic jack to press his bunter.
The jig to hold the cartridge case being stamped is something I never thought about.
Definitely an advanced wildcatting operation.
Cheers !

Passed inspection at Zim customs with the hand marked cases.