.22LR "match" chamber ?

M

model14

Guest
I understand how one can ream a centerfire chamber for a tighter neck clearance and then turn the neck of the case to achieve the exact desired clearance (a "match" chamber giving a known neck to chamber wall clearance). This works great because you are reusing the same brass (handloading) that has been neck turned to a specific outside diameter. However, in .22 rimfire, you are not reusing the same brass and it may be a "crapshoot" as to what clearance you are going to get with each new cartridge, so why bother to ream to a custom clearance? Now, having said that, I am picking up on these forums that "match" may mean the chamber is just reamed smaller than the SAMI spec, so there may be cases where a particular brand of rimfire cartridge won't fit or eject. Is that what is meant by a .22 "match" chamber? I guess the higher priced .22 ammo has tighter tolerances on case diameter, thus allowing you to hold a smaller chamber diameter?
Thanks,
Richard
 
A true match chamber engraves the driving band when you chamber the cartridge. How much of the driving band is forced into the rifling is one of the variations between the different reamers.
 
As stated the match chamber will bite down hard onto the bearing surface of the bullet.

In a single shot type rifle the chamber dimensions will be quite conservative to minimize any chance of misalignment. To emphasize this the better smallbore shooters do not use the bolt to chamber the bulk of the cartridge. They'll push it up in there with a finger till it bites, then drive the bolt home to finish the job.

The better made 1022 Ruger variants often use a 22LR Benz chamber which is basically a match front half and looser back half to facilitate the action working.

Your better 22lr ammo, Lapua/Eley/RWS is all pretty dern consistent and uniform from one to the next. I imagine the cheaper stuff is pretty close as well.

If you want a dynamite combination get a known good lot of Eley Tennex EPS and have PTG grind you up a 22LR EPS chamber reamer. If your barrel's good and everything else works right it'll hammer.

Good luck,

Chad
 
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Would one of you gentleman be so kind as to describe a rimfire chamber to me? Obviously my familiarity with centerfire chamber dimensions and terms is not helping me here. I apologize that I am not at home where I can make the measurement myself, but is the bullet driving band diameter larger than the case, the same, or smaller (I suspect the same)? On my stock CZ 524, is the bullet typically engaged into the rifling lands? Do rimfire benchrest shooters play with bullet jump as we do in centerfire (by using different reamer dimensions)? Are throat lengths varied ? There is a ton of information out there on centerfire chambering (reloading manuals), but not much I can find on the subject with respect to rimfire. Thanks for your help.
Richard
 
PTG22lrreamerspecs.jpg
 
As the photo illustrates, it's a hole with a taper at the front. The taper bites the bearing surface of the bullet.

That's about it. The "kink" comes in with how much room you leave to facilitate function and the angle/distance the throat has. This is largely decided by the type of bullet used. The EPS bullet from Eley is a semi wad cutter looking thing so it's a little different than what's been popular for the last 10,000 years.

I've never heard of jumping a sm bullet in the quest for accuracy. a cardinal rule is you ALWAYS bite the snot out of it.
 
Aside from what's already been said, I've noticed that some .22 LR ammunition chambers tighter in my CZ 452 than other brands and types. Since I don't shoot rimfire matches the "best" rimfire ammunition I have on hand is Wolf "Match Target" which seems to require more force to chamber even in my old Winchester 47. It shoots well in both rifles too.
 
Gentleman,
Thank you. I am now an expert in .22LR chambering :D
Richard
 
Larry,
That is where 'camming' comes into play. An action with a lot of closing cam will chamber a round much easier than an action with inadequate/marginal closing cam. My Hall chambers the rounds much easier than my Annie 64 even though both chambers were cut with the same reamer.
 
Richard,
There's a little more to it and a lot more reamers available than on the chart posted. Then there's grinding tolerances of +or - 1/4 degree so a 2 degree could be 1.75 or 2.25 degrees:) Most rimfire smiths have their own specs on reamers and won't discuss 'em. But you got enough to get you started.
Of course I'm talking benchrest accuracy. Not much else matters.
 
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