Let’s talk about chambering 22’s

[ajdemar215]

It seems as there is a fair bit of witch craft and secret sauce involved with 22lr chambers and very minimal information out there about chambering them. Just about anyone with basic machining skills and a little bit of reading on the internet can bullshit their way through chambering a centerfire cartridge, that’s not really the case with rimfire.

More specifically what I’m referring to is the “jam” portion of chambering and choosing headspace.

From the few barrels I’ve measured, the case protrusion after touching the rifling has been .130-.140”. Is that always the case? Is there benefits from more jam? Less jam? Obviously at some point this becomes jammed past the bullet and isn’t really doing anything. Do you determine the jam based off the bullet “shoulder” and tailor that specifically to the bullet you’re choosing to shoot?

As for headspace, it seems as it’s either team .041 or team .043. Is there a benefit to going short and having some crush? Or should you plan on going long? I’d imagine this is a tailor it to what you’re planning on shooting.

I have a clymer match finish reamer and the first chamber I cut for my bergara shot well most of the time. Chambered to .135” of jam and .043 headspace. It had some random flyers from time to time which I think was more related to my tenon than anything else (helicoil set up essentially) and I ended up swapping the factory bergara barrel back on from extraction issues. I got a RimX on the way and I’d like to learn a bit more about the chamber itself before it gets here.

I’d mention reamers here to but man, that is a ton of Information and I’d like to keep this thread within some attention spans.

 

[68hoyt]

Following

 

[grauhanen]

A couple of things to think about.

There are all kinds of match chambers for .22LR. No single one of them is the unqualified preferred choice of the most serious BR shooters, which is to say a lot of different ones are used with great success.

A very important key to any match chamber and barrel shooting well -- assuming of course a good barrel (they're not all equal) -- is that the chamber is properly reamed, including being concentric with a very well finished leade.

As for headspace, there's probably too much time spent on whether it ought to be .041 or .043". For what it's worth, gun builders from Bill Calfee to Kevin Nevius have used or continue to use .043". When all else is equal, a .043" headspace can shoot either Lapua or Eley ammo very well.

The bottom line is that neither a particular chamber nor a certain headspace will guarantee results. With any good barrel/chamber that will always depend on ammo lot selection. No rifle, no barrel, no chamber, no headspace will cause a rifle to outperform the ammo.

 

[accurate obsession]

As far as the depth to which the rifleing engraves, the numbers you mentioned are fairly common. Some shooters in some disciplines may want it deeper or much deeper. The problem lies in that you get to point where a live round cannot be extracted.

As far as headspace, if you plan to use one brand of ammo, headspace to that ammo. Eley's rim is a few thousandths less than Lapua and that's probably where the .041/.043 numbers come from (thats the two I'm familiar with). If you want to shoot any ammo you can get, stay on the high end. I do not believe that headspacing to pinch the rim is ever a good thing, but I'm certain that someone will call BS on me.

And if you want an extra heaping spoonful of rimfire craft and secret sauce ask about slugging barrels .

 

[Hi-NV Shooter]

It seems as there is a fair bit of witch craft and secret sauce involved with 22lr chambers and very minimal information out there about chambering them. Just about anyone with basic machining skills and a little bit of reading on the internet can bullshit their way through chambering a centerfire cartridge, that’s not really the case with rimfire.

More specifically what I’m referring to is the “jam” portion of chambering and choosing headspace.

From the few barrels I’ve measured, the case protrusion after touching the rifling has been .130-.140”. Is that always the case? Is there benefits from more jam? Less jam? Obviously at some point this becomes jammed past the bullet and isn’t really doing anything. Do you determine the jam based off the bullet “shoulder” and tailor that specifically to the bullet you’re choosing to shoot?

As for headspace, it seems as it’s either team .041 or team .043. Is there a benefit to going short and having some crush? Or should you plan on going long? I’d imagine this is a tailor it to what you’re planning on shooting.

I have a clymer match finish reamer and the first chamber I cut for my bergara shot well most of the time. Chambered to .135” of jam and .043 headspace. It had some random flyers from time to time which I think was more related to my tenon than anything else (helicoil set up essentially) and I ended up swapping the factory bergara barrel back on from extraction issues. I got a RimX on the way and I’d like to learn a bit more about the chamber itself before it gets here.

I’d mention reamers here to but man, that is a ton of Information and I’d like to keep this thread within some attention spans.

I would suggest going to Rimfire accuracy.com and find the thread by Kevin Nevius and read about what he found over a 3+ year period trying different chambers. he found for Lapua a 1.5-degree leade with a 0.030 engraving off the ogive works great. from my experience it works great, and all of my barrels use this chamber spec.

Lee

 

[padom]

While all of these things mattered in chambering your traditional 22lr barrels....none of this is possible or matters if we are talking RimX...

RimX cannot have headspace set to your desired measurement like traditional 22lr chambers before it.....the RimX was innovative in its design of control round feed and using the tensioner....the bullet is held against the bolt face at all times by the tensioner preventing the bullet from sliding forward and causing ignition or light strikes prevelant in traditional 22lr chambers in various circumstances.

The RimX has a tenon print and required headspace that ALL RimX barrels get cut to...this is the only way the RimX works correctly....there is no...ah I want to chamber this barrel at 0.043" and another at 0.041...that doesn't apply or work with a RimX....

Headspace for RimX ends up being around 0.0455" +/- when chambered correctly.... RimX actions come with the headspace gauge to confirm

 

[accurate obsession]

While all of these things mattered in chambering your traditional 22lr barrels....none of this is possible or matters if we are talking RimX...

RimX cannot have headspace set to your desired measurement like traditional 22lr chambers before it.....the RimX was innovative in its design of control round feed and using the tensioner....the bullet is held against the bolt face at all times by the tensioner preventing the bullet from sliding forward and causing ignition or light strikes prevelant in traditional 22lr chambers in various circumstances.

The RimX has a tenon print and required headspace that ALL RimX barrels get cut to...this is the only way the RimX works correctly....there is no...ah I want to chamber this barrel at 0.043" and another at 0.041...that doesn't apply or work with a RimX....

Headspace for RimX ends up being around 0.0455" +/- when chambered correctly.... RimX actions come with the headspace gauge to confirm

It's been a while but I believe that is the top end of the SAAMI dimension for .22lr, so they've covered themselves for any ammo the customer may use.

 

[Hi-NV Shooter]

While all of these things mattered in chambering your traditional 22lr barrels....none of this is possible or matters if we are talking RimX...

RimX cannot have headspace set to your desired measurement like traditional 22lr chambers before it.....the RimX was innovative in its design of control round feed and using the tensioner....the bullet is held against the bolt face at all times by the tensioner preventing the bullet from sliding forward and causing ignition or light strikes prevelant in traditional 22lr chambers in various circumstances.

The RimX has a tenon print and required headspace that ALL RimX barrels get cut to...this is the only way the RimX works correctly....there is no...ah I want to chamber this barrel at 0.043" and another at 0.041...that doesn't apply or work with a RimX....

Headspace for RimX ends up being around 0.0455" +/- when chambered correctly.... RimX actions come with the headspace gauge to confirm

I believe this very design limits it to be only offered in a mag fed configuration. you cannot load single rounds and no single shot version would be offered because of the unique design. but for switching out barrels I would think there would be no problems and for someone wanting to experiment with different twist rates this is ideal

Lee

 

[Geno C.]

You can single load a RimX with a sled