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Posted: 12/19/2013 8:59:22 AM EDT
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Having an issue with a postie M-16 and hammer follow issues (Yes, the owner is a FFL07/SOT). We're going to try an H2 or H3 buffer to ensure it's not bolt bounce. Uppers in question are a DD MK18 and a 11.5" built with a Noveske barrel. Both run fine in semi, and will fire 1-3 shots in auto before the hammer follows the bolt forward on a live round. Could also be a timing issue, which I'll measure, but will likely require a new lower being drilled if the sear pin hole is out of spec since there's no easy way to adjust it. Any suggestions? Currently the rifle is wearing an H buffer.
ETA: The rifle ran fine suppressed and unsuppressed for a couple thousand rounds up until now...which doesn't make much sense. It's not short stroking (locks back when one round is loaded into a magazine and fired...in semi and auto), and nothing was changed on the lower. Ammo was a variety of Wolf, handload M193 clone, LC M193, Fed M193, and FC M855. Same issue with all ammo types. |
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When you say it ran a couple thousand rounds suppressed and non-suppressed does that mean it ran fine in full auto previously and now doesnt or were those couple thousand round in semi only? That would tell us if you have a timing issue on the autosear or not.
If it previously ran in full auto and then started running in bursts and you have an H buffer in there it honestly sounds like bolt bounce to me. When the gun is new and the gas rings are tight the friction of the rings themselves will retard bolt bounce to a degree. A couple thousand rounds down the pipe has also probably opened up the gas port in the barrel via erosion slightly and is now sending more gas down the tube leading to increased carrier speed. Your hammer spring may also not be quite as robust as it used to be as well, which helped to reduce the rearward carrier speed. You may have been marginal in terms of functionality with a short barrel and an H buffer (which isnt the best setup for a short barrel) and now that the gun is more worn/broken in you are now no longer in the marginal functional range but have dropped into the partially non-functional range or operation. I would change your gas rings, put a new hammer spring in, and switch to H3 buffer in it and I am willing to bet your hammer follow issues will go away. |
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Quoted:
When you say it ran a couple thousand rounds suppressed and non-suppressed does that mean it ran fine in full auto previously and now doesnt or were those couple thousand round in semi only? That would tell us if you have a timing issue on the autosear or not. If it previously ran in full auto and then started running in bursts and you have an H buffer in there it honestly sounds like bolt bounce to me. When the gun is new and the gas rings are tight the friction of the rings themselves will retard bolt bounce to a degree. A couple thousand rounds down the pipe has also probably opened up the gas port in the barrel via erosion slightly and is now sending more gas down the tube leading to increased carrier speed. Your hammer spring may also not be quite as robust as it used to be as well, which helped to reduce the rearward carrier speed. You may have been marginal in terms of functionality with a short barrel and an H buffer (which isnt the best setup for a short barrel) and now that the gun is more worn/broken in you are now no longer in the marginal functional range but have dropped into the partially non-functional range or operation. I would change your gas rings, put a new hammer spring in, and switch to H3 buffer in it and I am willing to bet your hammer follow issues will go away. Yes it ran flawless up until now in auto. Appreciate the response and I though about the gas rings last night but forgot to add that in my post. Appreciate the help and I'll let you know when it happens. |
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Exact same thing is happening to mine. I just replaced everything in the fire control group. I had a Geissele SSF trigger in it and it ran fine for thousands of rounds. Now I have some no name trigger/sear/disconnect and safety selector in it. I also tried a different upper to isolate the problem and I still could not get it to run in full auto. I tried putting in a spikes tactical H3 and that didn't fix the problem. I will now put in a standard H3 buffer and new spring. Around the DFW metroplex it is a little hard to find a place you can take a full auto and dump a couple of mags so I have not had a chance to see if that has fixed the problems.
For you I would try a different upper and bolt and if you are still having problems then you can look at the lower. My auto sear hole is a little larger than the pin now and has a very small wobble so if after replacing just about everything that makes a full auto full auto then I may have to get my sear holes redone. Let us know if you find a fix because I would love to have my baby back. |
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Quoted:
Exact same thing is happening to mine. I just replaced everything in the fire control group. I had a Geissele SSF trigger in it and it ran fine for thousands of rounds. Now I have some no name trigger/sear/disconnect and safety selector in it. I also tried a different upper to isolate the problem and I still could not get it to run in full auto. I tried putting in a spikes tactical H3 and that didn't fix the problem. I will now put in a standard H3 buffer and new spring. Around the DFW metroplex it is a little hard to find a place you can take a full auto and dump a couple of mags so I have not had a chance to see if that has fixed the problems. For you I would try a different upper and bolt and if you are still having problems then you can look at the lower. My auto sear hole is a little larger than the pin now and has a very small wobble so if after replacing just about everything that makes a full auto full auto then I may have to get my sear holes redone. Let us know if you find a fix because I would love to have my baby back. I may be up in DFW to shoot next Saturday if the weather holds out. If you want a place to try out your current setup full-auto and/or debug it shoot me an IM and we can try and coordinate to meet at the range and see if we can get it straightened out. |
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