Home Forums Hunting & Shooting Express Rifles and Big Bores Only The big 40+ calibers. What's your favorite?

Ron's comment from page 1 of this thread suggested using an H&H-based Ruger as the start for building a 458 Win Mag. The H&H case was the basis for a variety of 7mm, .300, 8mm, .338 & .375 cartridges. Are any of the Ruger M77 or Winchester 70's in those calibers suitable for reboring? Is there a general line of demarcation where the smaller calibers probably need a new barrel but the larger calibers could be potentially rebored? I was curious about this but my Google-fu skills failed me & I was unable to get a definitive answer (which may not be possible without a specific measurable rifle in hand). I left a voicemail for Jesse at JES Reboring to chat with him but he hasn't returned my call yet. If someone has an opinion or knowledge on the question above, then answering it with the notion of shortening an existing barrel to match the 20" Ruger Alaskan Guide Gun would be an option worth factoring in. One of the reasons for asking this question is that in the left-handed selections, 7mm Rem Mag's are the most widely available along with the .300 Win Mag. So I didn't know if reboring was an option on a rifle chambered in the smaller calibers, if it was possible with caveats or if rebarreling was the superior way to go. If it's the last option, I know that Pac-Nor, Douglas & McGowen have all been mentioned in this thread as replacement barrels. Does anyone have a preference on who they recommend dealing with? Did a vendor you like not get included in that list?

You can’t use the barrel off a 375 Ruger to build a 458 WM because the chamber is already larger than the 458 WM chamber. Besides, I think a 20” barrel is a little short. A better option is a new barrel but have it contoured to match the profile of the 375 Ruger barrel and re-use the sights and barrel band. While your at it have your smith add a barrel mounted recoil lug to distribute the recoil. This would make a handy all weather 458 WM.

Hey JFE,

Thanks for the reply and the tip about the recoil lug. The question about the 20" Guide Gun was in reference to the 7mm Rem Mag & 300 Win Mag stainless rifles that I keep seeing. Basically what I was asking was if reboring a 7mm RM or 300WM all the way out to the full length of a 24"+ barrel would leave the barrel too thin at the crown, would it be possible to rebore it if the barrel was shortened to match the style of a 20" Alaskan Guide Gun. If someone had information about reboring, I didn't want them to think they were constrained by the dimensions of the full length of the original barrel if shortening it down to a thicker section was a workable option.

Normally you need about 0.125” of barrel thickness post reboring.

So in a 458 you need 0.458” + 2 * 0.125” = 0.708”

Some might do less than that but 0.125” is normally considered the minimum. As you mentioned, you can shorten the barrel as long as the barrel thickness at the muzzle is achieved.

Thanks again. Now that you've posted this useful information, it seems that reboring any of the other calibers that use the H&H parent case might not be doable or advisable even for the larger ones. Reboring isn't something that I have done before or thought about much. But putting calipers to various barrels in my gun safe made me realize that a lot of them were more slender & thinner than I thought they were in the middle of the barrel. I knew the end of the barrel would be problematic but the barrels I currently have all taper faster than I thought. Not a lot of extra metal to shave off there.

JFE as usual is correct.
Best job requires new .458-cal barrel on a Ruger M77 Hawkeye for a .458 WinMag.
If you get a bedding block stock you do not need the secondary recoil lug on the barrel.
Left hand: Does Accurate Innovations do one for the Ruger M77 Hawkeye Left Hand ?
Does HS Precision do one ?
Too bad Bell & Carlson does not !
Barrel makers I have used in order of greatest frequency to least: McGowen, Pac-Nor, Douglas, Shilen, Dan Lilja, Krieger.
Overall easiest to order by their 'puter system: Pac-Nor.

There aren’t many lefty synthetic stocks and those that do make one, generally it’s for a Rem 700 action. One supplier worth considering is MPI in the PNW. They say they can make lefty versions of their stocks.

Pacnor also do pre-fit barrels for a number of bolt actions and have a wide range of options of twist and profiles. The cost is fairly reasonable and pre-fits require minimal fitting by your smith. They used to have a 458 WM no throat reamer listed in their wildcat reamers section but I didn’t see it listed when I last checked.

As many times as I've reread this thread it's embarrassing to have forgotten you did a nice writeup of barrel profiles & sizes in the middle of page 5. I must have been having a senior moment when I asked my reboring question yesterday since all the information I needed was posted weeks ago. Occasionally I get stuck on stupid...


Their website looks really promising. I'll send them an email or give them a call & find out what they can do for me. Recently I saw a stainless LH Ruger 7mm RM with a laminate stock that caught my attention as a possible starting point. But I remembered Ron's 470 Mbogo (aka MuleNear) from page 2 with its broken laminated stock and thought synthetic does appear to be the superior option if I can get it. Thanks for the tip.




Taking a look at the bullet mentioned above, there's a caveat posted about twist rate. Since McGowen for example has twist rates in 8, 10, 14, 16 & 18 for this caliber, would you recommend one as being the superior choice for a bullet such as this? If this rifle was going to be used primarily (exclusively?) for plains game and it could be more at the mild than the wild end of the power spectrum, is there a particular powder load / speed that is preferred?

Epilogue: First of all, a quick shout-out of thanks to everyone who shared advice, opinions & photos on this particular topic. I learned a lot! One of the things that that was readily apparent to me early on in this thread was that it would be really hard for me to make a bad or a wrong choice. Every cartridge being mentioned was more than adequate for my current goals since North America & plains game was what my hunting buddy was suggesting. I appreciate that everyone was willing to play "what if" and share some knowledge.

Because affordable, left-handed options that I like rarely appear, my gut instinct told me that fate & circumstance would probably play a part in my final choice. Most likely, the item that popped up first that I could successfully acquire would be the winner of this selection process. On page 6 of this thread a month ago, I missed out on a Ruger #1 in .404 Jeffery. The latest rifle to slip through my fingers was a left-handed Dakota 76 in .375 H&H:




I think most readers would probably agree that this is a nice-looking rifle that would suit my purposes. I also think that most readers (including myself) would also guess that there was a snowball's chance in hell that I was going to win this auction. With the extra Kahles scope and the boxes of ammo, I laughed at the $3k~5k pre-auction estimate but decided to play along & go as high as $5,500. But they blew past me so fast I didn't get to savor that fleeting moment when I was on top that lasted a blink of an eye before I got relegated to the list of losers. I like nice things but having to pay almost $8k to stay in the game was a bit too Gucci for me.

I was house sitting for friends who were on a road trip to Austin & hanging out with their pet menagerie so I decided to console myself by going outside & sitting in a bow stand for a couple of hours. I didn't see any deer this evening but it was nice being out in the woods. When I came back inside, a LH Winchester Model 70 Safari Express magically appears. Boom! Mine now! Like hunting for elusive game, left-hand rifle acquisitions are all about patience, perseverance & sometimes (like this purchase) speed & luck. I have to do my research (e.g. this thread) ahead of time and grab things with confidence when they appear because they often don't last long.



It's funny how fate & circumstance sometimes works out since earlier this week a batch of about a dozen LH Ruger 375 Guide Guns appeared on GunBroker at attractive prices. As soon as they appeared, they started disappearing just as fast:



Since my friend who keeps talking about going to Africa lives in the Seattle area, I often thought that visiting another hunting buddy in Alaska to go hunting up there might actually be a more probable scenario geographically and that this particular rifle would be an interesting model to use in that environment especially at that price. But I held off on purchasing one while waiting to see how things panned out with the unobtainable Dakota 76 which fortunately resulted in the much-admired Winchester 70 falling into my lap instead. Not a bad outcome.

If I was placing a bet when I started this thread 2.5 months ago, then the .375 H&H was always a prohibitive favorite: It was findable in LH models, it was affordable, it was a nostalgic classic, ammunition is ubiquitous, it was highly-recommended by people whose opinion I value and it was an all-around smart choice for my intended needs & purpose. What was totally unexpected was I would get infected by Riflecrank, CZ550,...,et al's enthusiasm (that borders on fanaticism ) for the .458 Win Mag. You guys have officially piqued my interest. As someone who likes too much empirical data and overthinking things, the 181-page (and growing) .458 Win Mag thread in this forum has been a lot of fun to wade through as I read every post. That's a bunch of information to try to absorb. Anyway, the stainless Ruger M77 MkII with a laminate stock that I posted a picture of in my previous post above should arrive at my FFL tomorrow. When it does, I'll jump over to the .458 Win Mag thread and see if I can coerce those guys into helping me cobble together something similar to Sir Ron's Alderella pictured below since this second new rifle is the same model except with the bolt on the "correct" side. Back in September, I would have said that the 404 Jeffery, 400/450 or 416 Rigby/Ruger/RemMag would have been the more likely selection. The .458 WM might not have made the top 5. Hopefully this Ruger will be another fun learning experience.



If I ever manage to break away from the southeast in my upcoming retirement years, then the final result of this thread and my current selection of larger calibers to choose from currently looks like this:

30-06 - Sako 85 Hunter LH
9.3x74r - Ruger No. 1S
375 H&H - Winchester 1885 Safari Octagon
375 H&H - Winchester M70 Safari Express LH
405 Win - Winchester 1885 Traditional Hunter (iron sights)
458 WM - Ruger M77 MkII LH

If I'm unsuccessful at taking an animal on either continent with that selection, I don't think I'll be able to blame my tools. The purpose of starting this thread was to put one more bolt action rifle into the safe. Surprise, surprise...it turned into two.

Late reply, but here goes:

MPI: I have one on a Dakota 76 African from back when it was the only thing I could find.
They take a lot of work to finish. I put an oak block in the hollow/foam-filled butt so as to have a solid to screw the recoil pad attachment.
I would rather use the Ruger factory laminate stock on an M77 MkII or Hawkeye with proper reinforcement.

404-gr/.458 Shock Hammer works well on plains game for 200-yard zero whether 2350 fps MV or 2500 fps MV.
Those velocities are easy from 16.9" barrel and 23" barrel respectively.
Many powders will do it all in the .458 WM.
My favorites for the 400-ish-grainers in no particular order: AA-2230, Benchmark, H4895.
H4895 can be used for the entire spectrum from 60% (no filler) to 110% (compressed after drop tube).

Twist: The standard 1:14" is best for greatest versatility.

Congratulations on your new donor rifle for a .458 Winchester Magnum build:



Except for mine being right-handed, that is the same rifle I turned into Ms. Alderella Shilen-Ruger the Knik Knocker.
The world is always better off with one less 7mm Remington Magnum.

Get a 1:14" twist stainless No.5 Sporter contour from Pac-Nor or McGowen.
You do not need to make yours as long or heavy in the barrel as Alderella, unless you want to.