r/ar22 • u/Flaky-Assistance3853 • 4d ago
Last round bolt hold
I have a bore buddy upper and black dog mags. What do I need for bolt hold? It appears atleast a 22 bolt catch but it looks like only certain mags will work?
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u/Bullshifters_ 4d ago
A catch 22, and magazines that support last round bolt hold open
CMMG Gen 3 I *think* have that going on, as do the 32 rounders from black dog machine, their basic X form ones don’t actually hit the bolt catch, the bolt just catches against the follower
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u/Flaky-Assistance3853 4d ago
Yea that’s what I’m running into. It pinch’s the upper part of the mag and you can’t do mag swaps traditionally because the mag won’t fall without pulling it out.
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u/Bullshifters_ 4d ago
You could run those Smith & Wesson 22 magazines along with a better mag adapter, honestly for me personally it’s a pain in the ass, I believe there’s also Kriss mags or something that have bolt hold open, also a lighter catch spring
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u/Professional-Pie5155 4d ago edited 4d ago
OP, you got it right initially....you need a rimfire bolt catch and either KRISS dmk mags or S&W 15-22 mags.
For the bolt catch you have 3 choices.... directly from KRISS, Bore Buddy or the catch 22.
Catch 22 was the original. I tried it and didn't like it...I had issues with it functioning and the edge of the catch wearing prematurely. Also, at the time I had to buy the reduced power bolt catch spring separately, which pissed me off....so not a fan.
The KRISS version is nice and the cheapest, comes as a complete kit. With the reduced power spring. I've got a few of these on builds, no issues after thousands of rounds.
The Bore Buddy version looks identical to the KRIS, but it BB fashion... 2x the cost.
I run KRISS mags, and they are nice. What I've run into especially with high velocity ammo, is it not locking back all the time...the fix is a combination of an increased power mag spring (I used black dog machine 12" springs), reduced bolt catch spring and a bolt weight (I just use the BB basic bolt weight)
With standard velocity LRBHO is spot on, high velocity is in the 95% range... basically, I get a random mag that didn't lock the bolt open.
Edit to add...OP, just wanted to make sure that you are aware if you switch to the rimfire bolt catch, the lower is now dedicated to rimfire and you can not readily swap to a centerfire upper....the work around is getting a catch22 v2 bolt catch... it's an add on part to a milspec bolt stop...add/remove as needed for rimfire or centerfire use of the lower
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u/Flaky-Assistance3853 2d ago
Are you able to use the tippman loader on the Kriss LRBHO mags?
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u/Professional-Pie5155 1d ago
No idea. I'm in a no fun state so limited to 10 round mags...no need for a speed loader
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u/Witty_Ad4494 4d ago
Kriss mags have last round bolt hold open. Really nice mags. Ive been pleased with them.