Many years ago, I acquired a nice sporterised 1908 Brazilian Mauser in 7 x 57mm but the barrel was rusted out. I had several .308 Win ex-target barrels and thought about rebarrelling it to .308 Win. Previous experience with another Mauser was that the feed rails and magazine had to be altered and I was never satisfied that it fed properly.

I thought about having it chambered to .308 x 57mm as that would feed correctly through the magazine, but as I was about to send it off to the gunsmith, I acquired a free large ring 6.5 x 55mm barrel. Now I have another mauser, I am thinking of actually doing it.

Has anyone actually chambered and shot a .308 x 57mm ?. I would have thought that it would have been a common wildcat.

No I haven't, but IMHO with a deep throat and a fast twist it certainly woud out shine the .308. roger

I think it would have been a great idea too. Several years ago I posted a similar question on AR and the response was that the .308 and '06 could be used and eliminated ammo supply problems. Of course that never seemed to stop other wildcats did it! Truly though, most '06 rounds will function fine through a stnd 98 action with no mods. The heavier bullets and military ball require the mag box to be lengthened slightly. I've experienced the .308 feed issues too. I did discover that a 1909 Argy action will feed .308 flawlessly. The 09's have straight taper feed rails vs most other 98 types that have shoulders at the forward end of the rails. This is where the .308's tend to hang up.

Two other rounds that are close to the .308x57 would be the 7.5x54 French and the 7.7 x58 Japanese. The French case is basically the 6.5x55 Swede necked up, and it will function fine. My reference shows the Jap case apparently had thinner necks than US brass and ends up with the same outside neck diameter. If that is true, you could chamber a .308 barrel for 7.7 Jap, use reformed '06 brass, a .308 expander, and be spot on.

I think that would be about a duplicate of the 7.65 Argintine Mauser cartridge. Except I think the bore diameter for it is .311 instead of .308. I think case shape and taper is about the same as the 7 x 57.

So seems you desire good feeding with little smithing and a larger bore with 308 barrels on hand.

I like the idea.

I have been thinking of the 411, 375, 358 and 338 versions and improved versions on the 57mm length and a tad longer.
With the target barrels and larger capacity over the 308 you can drive heavier, high BC bullets faster and that can be a good thing for 600+ yard shooting.

keep us updated!!!

if you have a 308 chamber, you'll have to cut most of it off .. the shoulder is far larger ... unless you wanted to do a 7.65arg AI

These are 30" Palma barrels .3075 x .298' with a very large shank - plenty of material to cut the entire .308 chamber out. I toss my Palma barrels out at 3500 rounds and this will leave plenty of good rifling. While I do shoot .303 British and have plenty of .311" projectiles, the 7.65 Arg has no appeal.

Use a 30-06 reamer and short chamber it using 7x57 headspace gsuges. No custom reamer or dies needed. Dies are easy to shorten.

Or use a 308 reamer but go deeper.

Bruce

The problem is (1) that the 30/06 reamer is tapered and if you regard the .30x57 as a short chambered 30/06, the case base is very tight as the reamer produces a chamber rear that represents the case diameter 6mm up from the base. (2) Additionally, the reason for a 57mm case was to utilize the exsisting feed rails and avoid having to modify them. For instance, one suggestion was to long chamber the .308Win. This has a bigger diameter at the shoulder of the case. Examples are, 7x57mm is.431", 8x57 is .434", 7.65 Arg is .425", .308Win is .454" and the 30/06 is .441".

My original idea was to avoid a custom reamer and use a replaceable pilot 7x57mm reamer and then a separate .30 cal throating reamer. That idea fell apart when I could not find a gunsmith with a replaceable pilot 7X57mm reamer. I will have to settle for a 8x57mm reamer and have it's throat area reground.

In the meantime, has anyone actually heard of the .308x 57mm being used ?.

There is a very similar round to what you have in mind in France. It is called the "30-06 Sporting" of the "30-06 Short" (I forget which).

As military calibres are banned in that country they screw the barrel into the receiver one full turn. So standard 30-06 can't be chambered then lengthen the chamber to a uniform length unique to this "Sporting" or "Short" 30-06.

I am sure that RCBS has dies. They may also have dimensions or advice on a reamer supplier?

A friend has a very nice old Rigby that was a 7x57, the bore was gone. He sent it to van patten I think it was, who rebored it to 30 cal and then neck and throated it to 30 cal from the original chamber. I worked up loads to .308 level and left it at that. As he was useing the open sights and wasnt going to D&T the reciever, and I didnt see any need to run it at full max for a flat trajectory or anything.

If i rememer it right, there was an artikel about a round named .30 Mauser in "Precision Shooting" not too long ago. Think it was a x57 Case using 308 Bullets to get somethin between a 308 and a 30-06

Best
2RECON

7,5*55 swiss would fit well, norma makes brass.

quote:

Originally posted by KimW9:
Additionally, the reason for a 57mm case was to utilize the exsisting feed rails and avoid having to modify them.

If that's the case, the 30-06 is your answer. You should be able to run standard '06 cases through a 98 mauser with absolutely no mods to the feed rails, at least we've never had to...

FWIW-
My sillywet rifle is a .30 cal based on the 57mm case, and I really like it. The problem of short-reaming an '06 was handled by starting with a .30/06 AI reamer, then shortreaming by 1/4". Works fine.
Since my rifle is a single-shot, tho' based on an M98 Mauser, I still feed it through the "magazine." The stock wasn't cut out for the box, and I just drop the cartridge into the hole, and the base of the case is above the bottom line of the bolt-face. The bolt picks up the case as I close the bolt, and it feeds normally.
The result is a cartridge just a small amount slower than a full-length '06. I feel it has less bolt-thrust, so I'm happy.
I use a Sierra 165gr boattail at 2890fps. The load is a full-case of H4350 and a CCI 200 primer.
5-shot groups average .75MOA to 500yds, BUT...and this is the rub, The reamer cut a very long throat, so the boattail is only seated .10"! A I load from the plastic box to the barrel, I have no problem, but if you were to try the same thing, I'd use a reamer with a shorter throat, or no throat, and a separate throat reamer.
My barrel is 26", but I think it would make a nice hunter at 24" or even 22", if a guy doesn't mind a wildcat, like I do.
Have fun,
Gene