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Posted: 12/16/2006 8:31:34 AM EDT
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This last weekend me and a buddy were at the range and his RRA 9mm decided to have the same malfunction as mine had a few weeks ago. The bolt catch on his rifle broke in half at the roll pin. This is exactly what happened to me. I replaced my bolt catch, roll pin, spring, detent and everything is 100% now. He did the same because when mine broke I ordered twice as many parts as I needed just in case. Good thing I did. What are the odds of this happening? We bought the rifles from the same place within a few weeks of each other. These are factory rifles and are 9mm marked lowers. We both use promags which work 100% in both of the rifles. Sounds like a bad lot of mim parts to me. What do you think? Anyone else have this problem with broken bolt catches breaking at the roll pin? |
| I had one break the same way. I was bump-firing when it happened. I order a replacement from Garrison MFG and haven't bump-fired or had any problems. |
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Q buffer or WECSOGed spacer to reduce the bolt overtravel will solve this problem. Colt system 9mm allows bolt overtravel, which means that the bolt can accelerate under spring pressure for something like 3/4"-7/8" before hitting the bolt catch. Reduce that to less than 1/4" overtravel like the 5.56 bolt/carrier has and the bolt catch breakage problem is greatly reduced. |
Spacer? Do you mean some sort of object in the buffer tube? Currently when I remove the buffer and spring there is nothing in there. Shouldn't there be a white plastic stock spacer inside there? If so WTF! Why did RRA not insall it? |
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All this was hashed out over a year and a half ago, these archived threads have most of the relevant discussion... archive.ar15.com/forums/topic.html?b=3&f=15&t=228620 archive.ar15.com/forums/topic.html?b=3&f=15&t=229633&page=1 archive.ar15.com/forums/topic.html?b=3&f=15&t=228620 The premium solution is to get a 9mm Q buffer... ar15.com/forums/topic.html?b=7&f=120&t=229073 That plus a ramped bolt solves most of the idiosyncrasies with the 9mm AR (colt style) platform.
No there should not be anything in there from the factory. We are talking about informed modification to the system to improve function, reliability, and durability. Whether the manufacturer should modify their design to incorporate these changes is another question. |
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I also read through the threads that Gamma linked to. While I agree that a special extra heavy and extra long buffer is the elegant solution, why not just put a spacer down in the buffer tube that limits buffer travel? There were a couple pictures missing in the archived thread so maybe this is what was in the picture. I just pulled out my 9mm and did some quick measurements and came up with this:  If your 9mm is otherwise working fine, this ought to solve the bolt catch breakage issues... If anyone needs one, I can offer them for $15. |
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You want as much mass in a 9mm buffer as you can get. At least run the standard Colt type steel 9mm buffer. Hahn Precision makes an extended steel buffer that shortens the stroke AND you can still use the bolt hold open. There are other custom buffers that go even further to the point where you can't use the bho....I highly recommend against using these.....it is a matter of range safety. Spacers at the back of the buffer tube are a bad idea....shortening the stroke without increasing the weight makes for a very fast cyclic rate. More energy is dumped in the buffer tube when it hits rather than in spring travel. |
I was talking about adding the spacer to an upper already using a 5 oz buffer. In my case, I run a rifle buffer and buffer tube and there is still the overtravel. The simple spacer pictured above makes it so there is only 1/4" of overtravel beyond the bolt hold open. |
Just fill out a service order form with your contact info and mail it in with $17 ($15 plus $2 shipping) to the address on the bottom of the form. Make a note in the comments box that you want a 9mm buffer spacer. |
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