7mm-08 to 7x57AI

[1000yardstare]

Have a chance to buy a Rem 700 stainless SPS in 7mm-08. About half a box of ammo through it. Excellent shape.

A gunsmith/friend of mine has a reamer for the 7x57AI which P.O. Ackley describes as one of the better "improved" cartridges in his two volume set of books. My understanding is that one reason Ackley blew out cartridges was so the higher pressure loads could not be chambered in weaker small ring Mausers such as the Spanish 7mm Mauser that Teddy Roosevelt faced on San Juan Hill.

So my friend and I are kicking around the idea of rechambering the SPS to 7AI. He wants to set the barrel back one turn to make sure the rear of the chamber is cleaned up. Hopefully don`t have to modify the magazine rails for smooth feeding of the straighter case. Don`t think there will be a COAL problem with bullets up to 150 grs. Heavier than that and the base of the bullet will be below the donut.

Redding makes reloading dies for the 7AI so that won`t be a problem.

Anyway, was wondering if any members of this forum have done this rechambering and their opinion of same even if you haven`t done it.

 

[dan06]

I would take a good look at the coal in the 7X57 imp in a short action....I had one in .257 roberts and it was a little short for for anything over 100 grain bullets.

I have a .280 ack and love it. I suspect I would also like a 7X57 ack just something to check on before you rechamber.

 

[1000yardstare]

Dan06. I agree on the concern of COAL with heavy bullets. I have owned three .257 Roberts in the past, all in short actions and the 117s had to be seated with the base of the bullet below the shoulder of the case.

So I have already anticipated a similar problem in the 7AI in a short action with bullet weights over 150. But then there is enough horsepower in the 7AI to launch 162s at a good clip even if they have to be seated deep.

My gunsmith friend is suggesting that I stick with 140 Nosler partitions which would have plenty of punch for any North American game except the big bears. They should launch around 3000 fps in the 7AI.

 

[shootsanything]

I don't think it will work. I have a Rem 700 short action and I also have 7x57 - so I grabbed a loaded round just to see if it would have a chance and I had to take the bolt out to get the loaded round out of the feed port. There just isn't enough room.

Having said all of that - there is nothing wrong with a 7-08.

 

[1000yardstare]

Shoots, thanks for the input. I have a 6AI F Class rifle built on a 722 action. Loaded rounds with 107 SMKs are too long and will not eject normally but have to be pulled out with the bolt. But no problem with lighter bullets.

So the question I have to ask myself is do I want to restrict bullet weights to 150 and below in the 7AI in a short action so they can be ejected normally?

 

[dan06]

The .257 roberts I had was a factory rem 722 It was a good shooter but the throat was too long for the mag if you know what I mean. All the good shooting loads I ever found for it wouldn't feed through the mag. I never got mag legenth ammo to shoot any better than MOA. ammo with OAL that wouldn't feed would shoot 1/2 to 3/4 moa.

Now a new build you could have a short throat.....You would still have pleanty of mustard for hunting with 7X57ack

 

[alf]

I think you should buy it and just shoot it as is.

I've got a 7-08 with a 22" Rock barrel that shoots 140's at 2950 and 120's at 3150.

I don't think the magazine hassles with the 7x57AI are worth the minor gain you're contemplating.

 

[1000yardstare]

Alf, thanks for the input. As was stated earlier in this thread, the 7-08 is a good cartridge so why change it.

The rechamber to 7AI is just an idea my `smith and I are kicking around because he happens to have the reamer. But there seems to be potential problems with COAL and magazine rails that would offset any velocity gain.

Redding sells the dies for the 7-08 AI but I would have to buy the reamer and there is still the question of the magazine rails.

Anyway, no money has been spent yet. I wanted to see the reactions of other forum members before I proceed.