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Background was a lilja AR740 20", with slr adjustable gas block and UTG A2 stock kit, using a Magpul MOE rifle stock. BCG would occasionally pick up next round, but 90 percent of the time would be empty chamber. After pulling gas block off several times and checking BCG i was comparing this guns action to my 16" grendels action. I finally noticed that the BCG was not going back far enough to lock on catch. So pulled buffer and spring and realized that the screw that holds the stock on the rifle buffer tube that came with the A2 kit was 1/2" to long. The buffer was hitting the screw that held the stock on. Installed shorter screw, now BCG locks back. Just need to get to the range and test fire and adjust gas system again.
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Last edited by LRRPF52; 09-14-2015, 09:42 PM. Reason: Changed status to indicate solution was found in title -
I love it when troubleshooting finds obvious problems, more so when my solutions actually work... Hope that solves the problem.
Jack -
Are you sure it's not an A1 stock you have, with an A2 buttplate screw?NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.comComment
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I had purchased an A2 stock kit, it came with Stock, rifle buffer tube,buffer, spring, and tube extension and screw, but i just used the buffer tube, buffer and spring and screw. I guess the magpul MOE rifle stock is A1 length, and i didnt realize the screw in the kit was made to go through that extension piece. so when i screwed in, i didnt realize how far in it went. i wish the stock would have come with the appropriate screw.Last edited by RAM2940; 09-13-2015, 10:52 PM.Comment
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With the A2 complete stock assembly, you have one additional part, and that is the spacer. When they did the specifications on the M16A2, and basically screwed up a really good rifle, the target shooters thought that a longer stock would be a great thing to have, never mind soldiers who actually have to carry and fight with their rifle.
Instead of making a new extension tube length, it was easier to make a spacer and longer buttplate screw to accommodate the longer A2 stock. The only good thing about the A2 stock was that it was constructed of a much stronger glass nylon material, and can take a beating.
For those getting into AR's, or who have been well-versed in assembly of carbines, but figured rifle stocks were all similar, this original length vs. A2 and spacer can bite you like it did. Glad you caught it.
Also, for reference, the Magpul PRS uses an original length RE tube with no space, and they provide their own buttplate screw for it.
The MOE also uses standard length tube without the spacer.NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.comComment
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Ram,
Glad to hear you got it sorted eventually.
The butt screw was too long - Now who would have thought that straight up? When the bolt doesn't lock back I'm thinking half a dozen other possible reasons. Got to file this one away for a rainy day.
Some time back we had a similar situation when using MILSPEC screws on after-market pistol grips. The screw was too long and protruded into the lower receiver. It then limited the downward travel on the back of the trigger, which in turn minimised the clearance necessary for the tongue on the auto sear to clear the hammer on full auto. Functioned fine on semi and the screw is hidden below the trigger so not immediately obvious.
Big "AHA!" moment when the penny dropped so know how you feel.Comment
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