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Skeezix Offline OP
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I have an acquaintance that is a competitive shooter and avid and very experienced reloader, and is probably known by several people that post on this forum, so I'm not going to use his name. Anyway, he and I were talking recently about the differences in ballistics between the 7mm Weatherby Mag and the 7mm Remington Mag.

He noted that the Rem actually has a grain or two more case capacity than the Wby, when measured to the BASE of the neck. He also said that the only differences between the two that accounted for the increased velocity of the Wby (with same bullet) is that the Wby is loaded to higher pressures and that there is a little more freebore in the throat of Wby barrels. Ok, sounds plausible so far.

He added that the freebore was really a non-issue because he'd seen the Wby chambered in standard throated barrels and they shot Wby ammo and loads just fine with no excess pressure signs. Hmmmm, I thought, I'd like to see one of those rifles and its fired brass for myself. If you bought a Wby reamer wouldn't it have the Wby freebore already cut into it??

THEN he said that because of the slightly greater or equal USABLE case capacity of the Rem Mag, that, in modern rifles, you could often safely work up Wby Mag velocities in a Rem Mag by using Wby loading data in the Rem. He said that the Rem Mag loading data had been "wimped out" and toned down by SAAMI due to "weenie lawyers" over the years. And that the Wby ammo was loaded to European standards which are much more realistic as to what is truly "safe". That back in the day the Rem ran neck and neck with the Wby. I decided to check out some of that.

I've got loading data and manuals going back into the 50's and I dug it out, especially from the 60's and 70's, and found some of what he was talking about. I also have the Speer manual that very clearly states in it's section on the 7mm Rem Mag that the rifle they had previously used for testing their loads had an eroded throat and the previously published data was too hot for a normal rifle.

This is the same guy that turned me on to the "fact" that you can use 416 Wby data to soup up a 416 Rigby, as if my shoulder could stand it.

I'm not going to lie and say that I haven't exceeded the maximum shown in loading manuals by a grain or two a few times IF there were absolutely NO pressure signs and the chrono data looks good and stable. But, I've never exceeded published data by the amount of the differences shown in most manuals between the 7mm Wby and Rem.

His statements intrigue me, but they also sort of make me want to move several benches away when he's shooting his Rem. Anybody with any experience doing this? Is he playing with dynamite?


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I have run my 140 gr 7 Wby loads to 3400 fps in the winter time, and that was with the TTSX. Can't do that in the summer. And, I certainly would NOT expect the 7 RM to run at that speed without a trip to the hospital.

If you want 7 Wby speeds, better get a 7 Wby.


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Originally Posted by Skeezix
He also said that there is a little more freebore in the throat of Wby barrels.
He added that the freebore was really a non-issue.

If you bought a Wby reamer wouldn't it have the Wby freebore already cut into it??

His statements intrigue me, but they also sort of make me want to move several benches away when he's shooting his Rem.


There is more than just a little freebore in Wby chambers.

Freebore is very much a consideration between the two.

Yes, the reamer would have standard Wby freebore.



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Originally Posted by Skeezix
I have an acquaintance that is a competitive shooter and avid and very experienced reloader, and is probably known by several people that post on this forum, so I'm not going to use his name. Anyway, he and I were talking recently about the differences in ballistics between the 7mm Weatherby Mag and the 7mm Remington Mag.

He noted that the Rem actually has a grain or two more case capacity than the Wby, when measured to the BASE of the neck. He also said that the only differences between the two that accounted for the increased velocity of the Wby (with same bullet) is that the Wby is loaded to higher pressures and that there is a little more freebore in the throat of Wby barrels. Ok, sounds plausible so far.

He added that the freebore was really a non-issue because he'd seen the Wby chambered in standard throated barrels and they shot Wby ammo and loads just fine with no excess pressure signs. Hmmmm, I thought, I'd like to see one of those rifles and its fired brass for myself. If you bought a Wby reamer wouldn't it have the Wby freebore already cut into it??

THEN he said that because of the slightly greater or equal USABLE case capacity of the Rem Mag, that, in modern rifles, you could often safely work up Wby Mag velocities in a Rem Mag by using Wby loading data in the Rem. He said that the Rem Mag loading data had been "wimped out" and toned down by SAAMI due to "weenie lawyers" over the years. And that the Wby ammo was loaded to European standards which are much more realistic as to what is truly "safe". That back in the day the Rem ran neck and neck with the Wby. I decided to check out some of that.

I've got loading data and manuals going back into the 50's and I dug it out, especially from the 60's and 70's, and found some of what he was talking about. I also have the Speer manual that very clearly states in it's section on the 7mm Rem Mag that the rifle they had previously used for testing their loads had an eroded throat and the previously published data was too hot for a normal rifle.

This is the same guy that turned me on to the "fact" that you can use 416 Wby data to soup up a 416 Rigby, as if my shoulder could stand it.

I'm not going to lie and say that I haven't exceeded the maximum shown in loading manuals by a grain or two a few times IF there were absolutely NO pressure signs and the chrono data looks good and stable. But, I've never exceeded published data by the amount of the differences shown in most manuals between the 7mm Wby and Rem.

His statements intrigue me, but they also sort of make me want to move several benches away when he's shooting his Rem. Anybody with any experience doing this? Is he playing with dynamite?


Actually more modern pressure testing equipment which not only measures peak pressure but also records pressure-time curves has revealed statistically the distribution of the pressure characteristics is more dispersed for the 7RM than for other cartridges. So follows the need to reduce the average pressure level to reduce the likelihood of any particular shot to exceed maximum allowable level.

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Reloader 28: I suspected that the extra freebore was NOT really a non-issue, that it was there specifically to reduce the initial pressure spike and to give the bullet room to build some speed and momentum before it encountered the rifling - that that momentum was one component of the force necessary to swage the bullet into the rifling, thereby reducing or smoothing the pressure component of that force. I've read that the long freebore was an essential part of Roy Weatherby's engineering.

mathman: When I think of repeatedly exceeding a design limit, the stress/strain diagrams from structures classes in college come to mind. Once you exceed that proportional limit, the steel never fully recovers after being stressed. After I left the government, I worked in the specialty metals industry where we cold rolled and work hardened various steels and copper alloys, whereby we purposely and grossly changed the properties of materials by exceeding the proportional limit in a controlled environment.

Then we tested to destruction to verify the desired properties of the finished product. Depending on the material engineering, you could stress cycle a material for dozens, sometimes hundreds or thousands of times before it would fail, sometimes suddenly and catastrophically. I can envision a 7mm Rem Mag digesting 7mm Wby loads maybe a few dozen times, maybe even a couple of hundred times, and the steel in some component of the action slowly becoming work hardened/strained. Then one more round fired is fired and that component fails catastrophically. Most of us have seen horrific photos or heard stories of the destruction that is wreaked and what it looks like.


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Skeezix, I have both calibers on rebarreled 700's.. I found a load in the Re 22 data for my 7mm Rem.. It would get 3400 fps with a 140 Nosler BTBT... But my Wea. will run over 3500 with the same bullet..

Where I noticed the most diff. was with the 160's.. The long action and throat permitted me to seat the 160's flush with the neck of the Wea.. It turned up 3240 fps. with 7828.. I have never been able to get close with the Rem.. I like both rifles, but seldom shoot the much anymore..



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While some of the things your source says about the differences between the two cartridges are true, I'd be very leery about trying to apply 7mm Weatherby magnum data in loading the 7mm Rem Mag.

Anybody who has messed with enough 7mm magnums has noticed the differences in velocity from barrel to barrel, never mind trying to swap data from one to the other. I would not do it.

Provided however (here it comes grin ......years ago an old trick put forth by people like John Wooters and Bob Hagel suggested that you could throat a 7 Rem Mag to a 160 gr Nosler Partition with its base seated even with the base of the neck. This gives a substantially longer OAL(and longer throat), than many standard 7 Rem mag factory throats(which themselves vary a great deal even today). It takes a H&H length acton to accommodate these rounds.

W hile this is not exactly freebore, with this OAL and throat to match a 140 gr bullet will have jump to the lands.

I owned and completely shot out several of these barrels,hunted with them out west many times and killed a pie of deer, elk, and antelope with them over the years. And for a long time,never ran a 7 Rem Mag any other way. Back before we had RL 22, I used IMR4831 with 140 gr bullets and 7828 with 160's for velocities from a 24" barrel of 3250-3300 for the 140's, and 3100 for the 160's.

With some powders loads would approach 7mm Weatherby data, but the closest I recall was with H4831 and 160 NPT and BBC's. In that particular Krieger barrel, the rifle simply would not shoot until I maxed it out at 70 gr. for a velocity of 3100 fps. It had a long throat but I was jumping those bullets into the lands.

If you look at the Weatherby data in the Nosler manual you will see that it calls for 70.5 as a max load. There was no ill effect,case life was normal and there was never any outward sign of bad stuff. But then we need to remember that H4831 can be somewhat more forgiving than double based propellants. Incidentally I worked up those loads in mid summer and use the rifle to kill my last bull elk in Wyoming.

It's been said that 7mm Weatherby data is a good place to get started in loading for the 7mm Mashburn, which is a larger case than either the Weatherby or the Remington. But even then you have to be careful as some loads listed for the Weatherby are too hot in my Mashburn rifle.If the data is too hot in the Mashburn, there is simply no way that it should be used in a 7 Rem Mag.

You have to use discretion and understand that every cartridge is a wildcat once you start hand loading for it, and there are many variations in powder lots, bullets,,throats, internal barrel /throat and chamber dimension etc. Any combination of these can pile up to give different results...but generally I would not even try interchanging data between the two cartridges, even if an occasional rifle might come close.

Last edited by BobinNH; 11/23/15.



The 280 Remington is overbore.

The 7 Rem Mag is over bore.
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Bob, Nice to see someone remembers Hagel... To mee he was the best.. Liked him better than Elmer, as far as rifle choices.. Elmer was easier to visit with than Bob.. I tried several of these long throated rifles also.. Earl Etter was another fan of long throating.. Gunsport magazine had quite a few write ups on this and long range shooting in the 1960's..


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WCH: Hagel was a favorite of mine! I recall his articles on long throating the 7 Rem mag and the 300 Win Mag as well. Wooters too.

I also ran a few long throat 300 win mags.

As I recall, Etters was using dots in the reticle for long range before most of us knew what dots were... grin




The 280 Remington is overbore.

The 7 Rem Mag is over bore.
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You are right about Earl, visited with him on the phone several times and have a couple letters from him.. He got me set up with the dot system probably in the early 70's..

Wooters was a super nice man.. I ran into him at a pistol shoot one time.. His wife was a teacher and she and my wife got to visiting.. Had breakfast with them one morning.. Great memory..


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I've always had no issues using 7 Weatherby data in my 7 Mag.

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Seafire: Always? In how many rifles?




The 280 Remington is overbore.

The 7 Rem Mag is over bore.
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Using 7mm Wby loads in a 7mm Rem Mag is courting disaster.

The Rem freebore is .2845 diameter .1142 in length with a 3 degree lead (6 degree included angle).

Wby. freebore is .2844 diameter .378 in length with a 1.5 degree lead (3 degree included angle).

Looking in Nosler number 6 manual at the 150 partition the Remington 7mm Mag. uses 63 grains of IMR 4350 for a max load.

They Wby 7mm Mag. uses 66 grains of IMR 4350 for a max load which would equate to a 3 grain overload in the Remington.

I own both and would not tread there.

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My first question is why would one need to borrow Weatherby data? It's not like there's a lack of published info on the 7 Rem. mag.

If you are absolutely determined to use more powder just use the old data with the highest charge weight you can find and have at it (I'm being facetious). In the older manuals I'm sure you will find loads for the Rem mag that match or well exceed current Weatherby data.

As many of our members of the 'Fire with friends in the industry and in ballistic labs have related many times, the old methods of "judging" pressure were just "WAG's". Newer instrumentation used for the last few decades is far more precise and that's why the loads have been adjusted downward over the years.

I have several Remington 7 mags and a Weatherby and all of my Remingtons would show "pressure signs" (ejector marks, etc.) well before reaching the loads of my Weatherby.


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WOW..Will a 7 rem approach/equal 7mm weatherby performance?

Yes,IME with 26" barreled, long throat 7RM,VS my 24" 7wby, the RM will duplicate it.I have no idea what the pressures are tho.

Using Wby data in the RM? absolute horseshit. As BOBNH knows, some 7wby data will redline a Mashburn, think what thats going to do in your RM.

I load a lot for both, NEVER has the RM max been within 3 grains of what i've used in my WBY. My personal info is based on heavy bullets tho, maybe data on lighter bullets is closer, i dont know..But if you plan on using WBY data in your RM, you better be packing along a hammer to open the bolt.

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rosco well said.

The Nosler manual shows a max load in the 7mm Weatherby of 79.5 Retumbo wit 160 gr bullet for a velocity of 3189. In working with two Mashburns my buddy ran this load in his Mashburn for a velocity of 3280 fps. I backed off to 78 gr in mine with 160 AB and it ran across the screens at 3330 fps(?!).

Nothing bad happened but I suspended further testing. smile I would not speculate what would have happened in a 7 Rem Mag. This underscores just how hot some 7mm Weatherby data can be.

Rummaging through my brass box I actually found that box of 7mm Rem Mag hand loads,70 H4831-160 NPT mentioned above. In the rifle in which those loads were worked up they gave right at 3100 fps with the Partition and also the 160 Bitterroot.(For those wondering the rifle shot great and case life was fine).

I recalled that I fired that same load in another 7Rem Mag, a Len Brownell custom with what I think is a 24" Douglas barrel. In that rifle the same load gave 3210 or so. That's more velocity than i like to see from a 7 Rem Mag with a 160 gr bullet.

Please note that the Nosler Manual shows 70.5 gr H4831 for the 7mm Weatherby.

Like Rosco says you can get a 7 Rem Mag close to Weatherby performance with 26" barrels,longish throats for longer seating and considerable jump to the lands,and other factors. In SOME rifles your loads may even nudge into the vicinity of Weatherby data.

But unless you very deliberately build these factors into the barrel best to stay away from Weatherby data in the Remington cartridge in most rifles.And "long throating" a 7 Rem Mag essentially makes it a wildcat.

After a whole bunch of 7 Rem Mags here's where I feel comfy with the cartridge. Used to load it hotter but no more and when I see these velocities I stop, regardless what manuals say:

160-3050 fps.

150- 3125/3150 fps.

140- 3200 +- fps.

If i want more than that, i get a bigger 7mm.

None of this is to dump on the 7 Rem Mag of course; it' s great cartridge and any game animal will wither from a bullet fired at the ballistics cited above if we pick the right one for the job.


Last edited by BobinNH; 11/25/15.



The 280 Remington is overbore.

The 7 Rem Mag is over bore.
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Originally Posted by rosco1
WOW..Will a 7 rem approach/equal 7mm weatherby performance?

Yes,IME with 26" barreled, long throat 7RM,VS my 24" 7wby, the RM will duplicate it.I have no idea what the pressures are tho.

Using Wby data in the RM? absolute horseshit. As BOBNH knows, some 7wby data will redline a Mashburn, think what thats going to do in your RM.

I load a lot for both, NEVER has the RM max been within 3 grains of what i've used in my WBY. My personal info is based on heavy bullets tho, maybe data on lighter bullets is closer, i dont know..But if you plan on using WBY data in your RM, you better be packing along a hammer to open the bolt.


I agree with you roscoe. I only own two 7mm RM's at this time, but I'd never dream of trying the Wby loads in either.

Your comment about packing along a hammer reminded me of a really nice older Rem 700 BDL that a guy brought into our shop back in the 70's. It was a 25-06 and he had the bolt handle in his pocket. Seems he'd started handloading and decided to try some rather... ahem... "stout" loads in it.

He'd locked it up so tight that he'd been using a claw hammer on the bolt handle and had broken the brazed joint between the handle and bolt body. Knowing the guy's reputation as an ignorant, hot-headed, know-it-all azzhole, my partner and I decided we weren't going to mess with it, but we offered to ship the rifle back to Remington. He went for it. It took some real banjo work for the guys at Remington to get that rifle apart, and it wasn't pretty. They had requested a few rounds of that batch of his handloads and we had sent them along (could do that back in those days).

The rifle was deemed unrepairable, but it was a testament to the strength of the 700 action. The fired cartridge's primer was totally gone, the extractor was mostly gone, there was noticeable setback on the bolt lugs, and the receiver ring and barrel breech were just measurably stretched/expanded, not much, but enough that it wasn't safe to repair the rifle.

Remington didn't charge a thing for the disassembly and checkout, and offered a good price on a new barreled action that could be dropped into his stock (which was amazingly still intact and not cracked, IIRC). He took their offer and got back a nice rifle. This was in latter half of the 70's and I think Remington was glad to get to examine that rifle closely to see how their product held up to sheer stupidity.

I wish I could remember the load that was in that guy's handloads, but I vaguely remember that it was around 50gr of maybe IMR-3031 under a 120gr Speer. "Well that load works great in my 30-06 with a 150gr bullet and I'm only shooting a 120gr bullet in my 25-06."........ Sheesh.....

This was the same guy that badly bent the op-rod on a really nice Garand several years later, I heard.

Edited to add that this was also the same guy that was experimenting with a release trigger at the Trap and Skeet club one Sunday afternoon. I was taking a turn as trap-boy in the trap house, loading the clay pigeons, and the THIRD time this Bozo shot the back of the trap house, I threw out the red flag and came outta there. I'd had enough. Nobody else would load the birds for him, so he got pissed off and hit the road. Same guy also blew up a Rem 1100, B-grade skeet gun one day at the club. I wasn't there, but saw some pics of it. Don't remember how he managed that one.

Last edited by Skeezix; 11/26/15.

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