blaster113 Posted July 18, 2016 Share Posted July 18, 2016 (edited) Anyone use a spacer in the buffer tube of their 9mm AR? I'm running a CMMG 9mm buffer. I read someplace it's supposed to restrict bolt travel and prevent breakage of the bolt hold open latch. Is it a solution for a non existent problem? Edited July 18, 2016 by blaster113 Link to comment Share on other sites More sharing options...
M118LR Posted July 18, 2016 Share Posted July 18, 2016 Hope to here something about this. I built a 9mm carbine and I had a bolt hold open latch that broke. Link to comment Share on other sites More sharing options...
blairmckenzie1 Posted July 18, 2016 Share Posted July 18, 2016 Depends how far you bolt travels. If your set up lets the bolt travel far enough to pick up the steam required to break bolt catches, yeah. If not, no. Link to comment Share on other sites More sharing options...
2MoreChains Posted July 18, 2016 Share Posted July 18, 2016 I think it depends on the buffer you're using. For example, if you're using a standard carbine buffer you may need a spacer or about $1.75 in quarters in a stack to take up the extra space. I went with a Spikes 9mm buffer that weighs a little over 8 oz and is long enough not to need a spacer. Link to comment Share on other sites More sharing options...
blaster113 Posted July 18, 2016 Author Share Posted July 18, 2016 (edited) My CMMG build used to run 100%. I put in $1.75 in quarters, then my rifle was doubling when my boys shot it. When I shot it I couldn't duplicate the malfunction. Disconnect works fine. Trigger is an ALG Quality Mil Spec. I'll pull the 9mm buffer, measure it against a carbine buffer and see if there's a difference. I didnt notice any difference when I completed the build. I'll also pull some of the quarters out. Edited July 18, 2016 by blaster113 Link to comment Share on other sites More sharing options...
M8Stealth Posted July 18, 2016 Share Posted July 18, 2016 Built a 9mm earlier this year. Pull the charging handle back and see how much room is between the face of the bolt and the bolt catch. The bolt just needs to clear the catch, add or remove quarters to achieve a small gap. From memory, think mine is about 1/8" Link to comment Share on other sites More sharing options...
blaster113 Posted July 18, 2016 Author Share Posted July 18, 2016 (edited) Built a 9mm earlier this year. Pull the charging handle back and see how much room is between the face of the bolt and the bolt catch. The bolt just needs to clear the catch, add or remove quarters to achieve a small gap. From memory, think mine is about 1/8" My rifle has a size able gap between the bolt face and latch when pulled back Edited July 18, 2016 by blaster113 Link to comment Share on other sites More sharing options...
M8Stealth Posted July 20, 2016 Share Posted July 20, 2016 Find your favorite state quarters, remove the buffer and spring and stack coins in the bottom of the buffer tube until the distance between the bolt and catch closes up. Link to comment Share on other sites More sharing options...
dynamicalflinch Posted July 21, 2016 Share Posted July 21, 2016 Spacers of the aluminum or nylon variety are cheap and easy. Slash makes some really nice and heavy (and expensive) 9mm buffers that are longer to eliminate the need for one. If you are unsure about needing one still... Take your empty rifle, pull the charging handle all the way to the rear, hold the bolt catch down, and sling shot the charging handle. Its a pretty nasty smack that translates not only to the bolt catch itself, but also the receiver near the magwell, the bolt catch pin, and the bolt catch pin holes. One more perspective, if you STILL aren't sure... Colt uses spacers in their factory guns, CMMG doesn't. Link to comment Share on other sites More sharing options...
blaster113 Posted July 21, 2016 Author Share Posted July 21, 2016 (edited) Spacers of the aluminum or nylon variety are cheap and easy. Slash makes some really nice and heavy (and expensive) 9mm buffers that are longer to eliminate the need for one. If you are unsure about needing one still... Take your empty rifle, pull the charging handle all the way to the rear, hold the bolt catch down, and sling shot the charging handle. Its a pretty nasty smack that translates not only to the bolt catch itself, but also the receiver near the magwell, the bolt catch pin, and the bolt catch pin holes. One more perspective, if you STILL aren't sure... Colt uses spacers in their factory guns, CMMG doesn't. I tested the gun today with only 4 quarters in the buffer tube. Had one double in about 75 rounds. Took all the quarters out after that. Good point about CMMG's guns not using spacers, and I didn't know Colt used spacers in theirs. Never had a rifle double on me before. 2011's with light trigger jobs, that's a different story hehe. I think I'll try this Spike's buffer next http://stores.9mmar.com/spikes-tactical-st-9x-heavy-buffer/ Edited July 21, 2016 by blaster113 Link to comment Share on other sites More sharing options...
jmnielsen Posted July 21, 2016 Share Posted July 21, 2016 I put a 9mm AR together and just 3D printed a spacer. Works perfect and cost me about $0.10 Link to comment Share on other sites More sharing options...
MickB Posted July 23, 2016 Share Posted July 23, 2016 Factory 9mm Colts come with a spacer. Another alternative is to use the VLTOR A5H4 buffer in a standard carbine buffer tube. It is perfect for length and is heavier than the Colt 9mm smg buffer. Mick Link to comment Share on other sites More sharing options...
StealthyBlagga Posted July 23, 2016 Share Posted July 23, 2016 Factory 9mm Colts come with a spacer. Another alternative is to use the VLTOR A5H4 buffer in a standard carbine buffer tube. It is perfect for length and is heavier than the Colt 9mm smg buffer. I just posted a comparison of the VLTOR A5H4 buffer vs. the standard 9mm buffer options: CLICK ME Link to comment Share on other sites More sharing options...
dynamicalflinch Posted July 23, 2016 Share Posted July 23, 2016 Beyond weird cycling and extra abuse and wear on the gun... I've seen it happen before I realized what the problem was at a match a few years back. The bolt being allowed to travel too far to the rear will often allow a piece of spent brass to sneak under the bolt and into the fire control group. When that happens, that gun will not fix itself for God or Country. It almost always requires the receiver extension to be removed, and sometimes blindly removing the hammer pin to loosen stuff up enough to get the brass out. Link to comment Share on other sites More sharing options...
JAF1680 Posted July 28, 2016 Share Posted July 28, 2016 The first one I built had a buffer spacer and I still broke the bolt hold open latch. Link to comment Share on other sites More sharing options...
Shadowrider Posted July 28, 2016 Share Posted July 28, 2016 I'm running a carbine tube, CMMG 9mm buffer, Wolff extra power carbine spring and a stack of quarters. It runs every hollow point +P and +P+ round I've thrown at it except for Remington 115. No issues yet. Link to comment Share on other sites More sharing options...
blaster113 Posted July 29, 2016 Author Share Posted July 29, 2016 turns out my issues with doubling were from the ALG trigger I put in. yesterday it went full auto so out came the ALG trigger group and the CMMG stock trigger went back in. Going to order the Spike's extended buffer in the morning. Link to comment Share on other sites More sharing options...
blaster113 Posted August 7, 2016 Author Share Posted August 7, 2016 Update if anyone cares ordered the Spike's ST-9X heavy extended buffer. With the new buffer when I pull the charging handle back the bolt barely clears the bolt catch at full extension. Perfect. Ejection used to be straight out the ejection port about 20+ feet; now the ejection pattern is slightly upwards, still straight out the port and distance is reduced to about 10-15 feet. Dot movement surprisingly improved. The dot now kind of lazily lifts a little then falls straight back down. There is a little more push to the rear during recoil now I'm guessing due to the 8 oz buffer moving backwards. Ammo used is my P226 132pf Production load; 125 grain BBI with some Solo 1k. This load chronos about 152 pf from the rifle. Spring is a std. carbine buffer spring. Only fired 100 rounds to test and so far I really like the setup. Bottom line; if starting a new build I would definitely use an extended buffer from the start. No need to screw with spacers. Link to comment Share on other sites More sharing options...
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