Bentz or Sporting 22lr reamer

I am working on an Erma RX22, 22lr pistol. The chamber is short. I believe the throat is not quite long enough, and the bullet shoulder is contacting the rifling. I hear European chambering dimensions for 22lr are different then the U.S. has, and this situation is not uncommon on their firearms with U.S. ammo. Some rounds don't quite chamber all the way, and I have misfires. Light hits, as I believe the FP is driving the cartridge all the way in, weakening the blow. The gun often short cycles also. Doesn't always pick up the new round. I believe there is extra resistance to extraction, because of this, siphoning the recoil energy. This is with HS ammo. I had access to a rougher reamer, and it took out a little swarf at the throat. This improved things noticeably, but I am still not there. I think a finish reamer will complete the job. Being this is not a target pistol, going bang is more important to me, than gilt edge accuracy. Which type reamer is most likely to get me where I want to be at?

They make a "semi auto match" which is probably the same as the Bentz.

You could also take an ordinary Clymer or other make of .224 centerfire throating reamer and just "kiss" the origin of rifling to enable rounds to chamber. You don't need a full chamber reamer.

I was fortunate of being gifted a box of misc reamers with the purchase of my lathe. The previous owner was gunsmith who specialized in single shot pistols, which was what these reamers were all for. In the box, I do have a 22 mag finish reamer, with a solid pilot, and a .223 finish reamer, with a live pilot. I think they are all Clymers. Which would be better for what I want to accomplish?

The .22 Mag. and .223 finish reamers have necks which are larger than the .22 LR chamber.

You want a throater only, which on a .224 centerfire will permit the exposed bearing surface of a .22 LR bullet to enter, without enlarging the chamber itself. If you chamber a .22 LR match round with large bullet diameter, such as Eley Tenex, you may get a slight squeeze, but typical US ammo will chamber freely without resistance.

A .224 centerfire reamer is too "large" to cut a proper chamber and or throat for a .22 long rifle, whether it be a Bentz, Match, Target or standard chamber. And a .224 pilot is too big to enter the bore to begin with.

You will most likely need a .222 pilot on your throat in and or chamber reamer.

I have cut or re-cut hundreds of .22 lr. chambers, and I have never seen a rim fire barrel that would even come close to accepting a .224 pilot.

IF by some one in a billion chance your barrel will accept a .224 pilot, if you recut the throat to the diameter of a .22 centerfire, chances are that it will be cut so far oversize, accuracy will suffer greatly.

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Originally Posted by GBertolet

I am working on an Erma RX22, 22lr pistol. The chamber is short. I believe the throat is not quite long enough, and the bullet shoulder is contacting the rifling. I hear European chambering dimensions for 22lr are different then the U.S. has, and this situation is not uncommon on their firearms with U.S. ammo. Some rounds don't quite chamber all the way, and I have misfires. Light hits, as I believe the FP is driving the cartridge all the way in, weakening the blow. The gun often short cycles also. Doesn't always pick up the new round. I believe there is extra resistance to extraction, because of this, siphoning the recoil energy. This is with HS ammo. I had access to a rougher reamer, and it took out a little swarf at the throat. This improved things noticeably, but I am still not there. I think a finish reamer will complete the job. Being this is not a target pistol, going bang is more important to me, than gilt edge accuracy. Which type reamer is most likely to get me where I want to be at?

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Does HS in this case refer to High Speed ammo?

In my experience in my custom match rifles with Winchester 52 match reamed chambers, high velocity or high-speed ammo does not fit the smaller match chamber. Match ammo is smaller. Some brands and lots of HS do not want to even go in and when forced to and shot, will not always extract well. Sometimes to the point of needing to be dug out with a tool.

This may or may not be of any help to your pistol chamber. I hope you get it going.

I misunderstood outpost75's initial response. My bad. Of course a .224 reamer would not work in the smaller 22 lr chamber for throating. I used high speed ammo, as that's what the manufacturer recommends, for sufficient recoil energy to function.

Bentz, all day long, thats on 22 chamber every smith should have. Reliable function and is accurate as heck. I even use it on sporting bolt guns.

Go to rimfire central and search reamers. There are numerous 22lr reamers. I would make a cast of my chamber and then measure the ammo and decide what the chamber needs. I would then select the reamer.

I did ultimately get a sporting rifle reamer. I found that this gun is so far out of spec. The pilot on the reamer is .216, and it will not fit in the barrel. The free roughing reamer's pilot I was given, was way undersized, so that's why it fit. Using pin gauges, the bore diameter is a very tight .210. The reamer pilot is of correct size, as it fits snugly in the muzzle of all my other .22 rifles, as it is supposed to. I have since, tried lapping the chamber and throat, with 600 grit emery cloth, and finishing up with JB Bore Paste. So far I have had 100% functioning. I hope this cures the issue. I didn't pay all that much for the reamer, and I now have one for future use.

Just out of curiosity, could I have turned down the pilot to .210, and later send it back to the manufacturer, to have a live pilot of the standard .216 size installed? I don't know if that can be done or not.

A .224" pilot is for a revolver cylinder. A rifle reamer is either a live pilot or .221" but to be accurate you would need to pin the bore in front of the chamber until you get a pin with a snug fit and use that same size pilot. You might need a .2215" if it fits better than a .221" I keep all these in half thousandths because .001" increments is too coarse for precise measuring.

The nominal groove diameter of the 22 lr is around .221-.222. The nominal bore diameter is around .216-.217. The pilot rides on top of the lands. You have to deduct the depth of the grooves to get the bore diameter. A set of pin gauges will verify what you have. I had a .210 bore diameter, which is exceptionally tight for a 22 lr. It might have extra deep grooves, keeping with the .221-.222 groove diameter. I have been told that the German standards, lean towards tighter dimensions. And that this issue is not uncommon with German pistols made during this era of 1960's-1970's.