I like the notion of single shot rifles chambered for rimmed cartridges.

The cartridge dimensions of the 7x57 and 7x57R appear to be identical except for the rim. Could a (standard/rimless) 7x57 chamber (in Ruger No. 1) be rechambered/given a rim cut and allowing you to shoot either rimmed or rimless in the same chamber?

Would the extractor likely need any modification?

If it would work, can you think of any downsides - except the more expensive brass.

Any thoughts appreciated.

It has been done on Blaser K95 single shot riflesd which were chambered for the rimmed version of the cartridge (6,5x57 (R) as well as 6,5x65 (R)). The extractor for the rimmless version had to be installed, otherwise I understand that everything was left as it was.

I have had the same thought as you over the years! You could use both rimmed brass and rimless brass in the same rifle, if a circular cut was made on barrel breech ring for the rim to seat, and the spring-loaded extractor/ejector appears to have enough range of movement to work with either type of case! I was thinking in terms of the Brenneke 7X65R/.30/'06 case families, but it would work out the same with the 7X57mm/7X57R cases.

I don't know about your particular rifle but I do know that Contender Smith's like Mike Bellm did/do this. One of the more popular that I know of is cutting a rim ecess for .307 Win brass in a .308 Win chambered barrel. Sean

Thanks to all for your input.

eldeguello: How close is the base diameter of the 7x65R to the base diameter of the 30-06? Would it be feasible to make a 30-06 Rimmed out of it by resizing and expanding with 06 dies?

I am no gunsmith, but i do understand that rimmed cartriges headspace on the rim, and rimless cartridges headspace on the shoulder.

I would need to be convinced that these are not incompatible or at least that they could both be achieved safely...

yet another issue: most of the difference between the rimmed and rimless rounds is that the rimless are loaded to higher pressures for stronger actions. I would hesitate to put a 7X64 load into my older 7X65R break actions rifles. Now with the jaeger style breech lock like the Blaser K95 adn the Merkel K1 adn K2 that may not be an issue.

But what is the advantage of bastardizing a stock rifle?

[ 11-13-2003, 06:44: Message edited by: Jameister ]

A friend of mine has a Competitor pistol that was factory chambered to accept both .307 Win and .308 Win brass. The difference between the two rounds is the rim. Sean