The latest trend in reloading is o-rings on cartridge rims

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Have any of you guy's done or do this. O-rings on cartridge rims to keep the case centred in the chamber. It's just for Enfields and other rimmed cases.
 
Have any of you guy's done or do this. O-rings on cartridge rims to keep the case centred in the chamber. It's just for Enfields and other rimmed cases.

I've heard of it and have seen pics of it on other forums, but I have yet to do it myself.

Apparently it lengthens the life of the brass as well.
 
I have read about it and have no interest in buying bulk o-rings to use on my rimmed ammo. There are a few "prophets" out there who say otherwise, but to me it's a fad that will end soon enough (although it really hasn't started).
 
Ok. I guess if you have excessive headspace it will hold the case against the boltface. I think you'll still need to use it for 2-3 firings, as brass spring back would still provide space between the rim and boltface. Once the bolt takes effort to close on the brass without the o-ring, you could discontinue its use and go a few more firings until you need to partial F/L size and then repeat the process. Typically undersized bases on 303 brass (oversized chambers?) and a bit of spring in the bolt of Lee Enfields still don't account to super long brass life, but I get "normal" brass life in my P14's.

Not a new idea at all, but perhaps the first time it's been widely communicated. I did the same thing a few years ago for fireforming brass whose rim was too thin, for use in an antique.
 
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I always used aluminum tape, but I suppose the o-ring would do a similar job.

Andy, could you explain the aluminum tape use more ? I think what TwoTone referred too ,"This would also prevent the 'tilted casehead' that is a fairly common sight with fired .303 brass " would help center the case and help accuracy. Jack
 
Andy, could you explain the aluminum tape use more ? I think what TwoTone referred too ,"This would also prevent the 'tilted casehead' that is a fairly common sight with fired .303 brass " would help center the case and help accuracy. Jack

Sure. Aluminum tape is adhesive on one side and usually about 0.002" thick - its primary use is to seal heating and cooling system joints. It can be cut with scissors, and a 1/4" wide strip just a bit shorter than the circumference of the casehead (leave a small gap so there's no "bump" where it overlaps) will increase its diameter by about 0.004". Two rounds gives 0.008", etc. In "generous" chambers, this centers the casehead - and after first firing it's concentric with the bore. American 303 Brit brass tends to be on the small side at the casehead, and paired with a large chamber, you might need 2-3 rounds of tape. You can remove it after, or just leave it there.
 
Cute idea.

Be aware though that a primer firing generates a remarkable amount of thrust, pushing the case forward very hard, before the powder ignites. So I'm not sure if the o-ring would actually hold the case aft firmly enough to accomplish the desired goal. You could easily test this though - take a primed empty case, chamber it (with o-ring installed) and fire the primer. Extract it, and see how far the primer has backed itself out of the case head - that's the amount the the case was pushed forward during the primer's firing.

If you have a cartridge case headspace measuring gauge for a rifle that uses a rimless case (e.g. .308 Win), measure a case's headspace, prime it and fire it (primer-only), then measure the case's headspace again. The primer has enough energy to push the shoulder back a few thou.
 
Have any of you guy's done or do this. O-rings on cartridge rims to keep the case centred in the chamber. It's just for Enfields and other rimmed cases.
I don't know about other rimmed cases, but a fair number of dedicated Lee Enfield enthusiasts do similar things to achieve the same result with new brass.

The so called "headspace" problems in Lee Enfields that can lead to short case life is simply the Brits very pragmatic way of dealing with the issue of ensuring reliability with any kind of groddy ammunition they might have squirreled away in some craphole part of their empire. Make the chambers large enough - no matter how dirty or fugly the ammunition, it will probably chamber. Good for reloading? No, but the Brits didn't care about that.

I have never thought to try an O Ring. I use tape at the back.

However, to really get the fit you are looking for also requires combining that with using a larger M die to open up the case mouth, and then resize just enough that the bolt will close on the case. What you will have at this point is a false shoulder partway up the neck, and a case supported both at the back and the front.. What this does is ensure as best possible that the case expands concentrically outward on first firing, without a lot of brass moving forward, stretching, etc. Whether it is worth the trouble is in the eye of the beholder, I guess.

Combined with a Lee collet die, this works very well.
 
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