BioHazard Posted September 9, 2011 Report Share Posted September 9, 2011 I just finished my first DPMS LR 308, I was so ready to fire it off today but it will not fully chamber the round. I pulled the bolt carrier and put a shell down in the barrel and it fully seats without any resistance. I then installed the carrier/bolt with the round still in the barrel. It takes a pretty firm push on the back of the carrier to rotate and lock the bolt into the barrel. I can then pull the charging handle and extract the shell.If I take the shell out and install the lower if I pull the charging handle all the way back and release it the bolt locks perfectly, if I slowly release it the fwd assist will push the bolt home.If I once again remove the lower put a shell in the chamber and let the carrier go forward until it stops the fwd assist will not push the carrier forward at all, its like its not forward enough for the fwd assist to engage.What's going on here, I have no headspace gauge but it really does not seem to be a headspace issue.Any ideas, BTW if it matters its a DPMS A3 upper.Thanks Quote Link to comment Share on other sites More sharing options...
imschur Posted September 9, 2011 Report Share Posted September 9, 2011 A few things. A lot of oil when new, maybe some grease on the lugs. If you are riding the carrier it will fail to lock. These guns are tight when new. You must let the recoil spring drive the the carrier with force. The forward assist on these is not like an AR-15, there are no serations. It will only push the bolt in one location. Quote Link to comment Share on other sites More sharing options...
BioHazard Posted September 9, 2011 Author Report Share Posted September 9, 2011 I have been chambering this thing for over 2 hours, everything is heavily oiled and without a shell the bolt rotates into place very smoothly. When I add the shell its real stiff still. Its appears that the ejector mechanism is where the tension is, I am going to continue to mess with it tonight but its really depressing.. Quote Link to comment Share on other sites More sharing options...
BioHazard Posted September 9, 2011 Author Report Share Posted September 9, 2011 Well I give, just walked in the backyard (yes its good to live in the boonies) and tried to chamber one, pulled the charging handle all the way back released it and it jammed before getting up to the chamber and put a nice dent in the case in the neck down. I dunno, I had high hopes for this build and I don't like to be defeated but I just may need to check out a gunsmith :'( Quote Link to comment Share on other sites More sharing options...
imschur Posted September 9, 2011 Report Share Posted September 9, 2011 right, it takes a fair bit of energy to rotate the bolt and get the extractor over the rim.I had a similar problem. My bolt was a little stiff rotating and it ruduced the amount of energy available to get the extractor over the rim of the case. My weapon would actually lock up. I would have to mortar the buttstock on the ground to free it up. Quote Link to comment Share on other sites More sharing options...
imschur Posted September 9, 2011 Report Share Posted September 9, 2011 I should add I would not have realized my problem If I didnt have another new BCG on hand. With the upper removed and my alternate bcg I could cycle the bcg on an empty chamber with my fingers without issue. With the original bcg there was no way in hell. That was without a cartridge to boot. Quote Link to comment Share on other sites More sharing options...
BioHazard Posted September 9, 2011 Author Report Share Posted September 9, 2011 The bolt seems to rotate quite easily, even if I ride the charging handle it just takes a small bump of the forward assist to send it home without a shell. It seems the issue is in the extractor mechanism, I am going to play with it a bit, I have not pulled the bolt apart something may be stiff in there. Quote Link to comment Share on other sites More sharing options...
Turbotezza Posted September 9, 2011 Report Share Posted September 9, 2011 You're good. Chambering a round should always meet with some resistance. Even when using a headspacing gauge, the instructions will always state the amount of pressure you need to put on the bolt while you do the checking. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 9, 2011 Report Share Posted September 9, 2011 Did you use a Rock River bolt assembly in this build, by chance? Not the whole BCG, just the bolt... Quote Link to comment Share on other sites More sharing options...
BioHazard Posted September 9, 2011 Author Report Share Posted September 9, 2011 Its a chromed DPMS carrier and Phosphate bolt.Another question in my long line of questions. Should the bolt travel the same distance forward with and without a shell? When its broke down and I push the bolt closed its about .125" further out then without a shell, is this normal? Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 9, 2011 Report Share Posted September 9, 2011 The resistance you are experiencing is not only from the extractor claw , but also the ejector button ,which gas a pretty stiff little spring in there.The fail to feed may be a mag. problem . Try a different mag. or manufactures mag , just to see how it works. More likely a newly built firearm's break in tweeking. Need to get some working out of the bugs , like bullets down range. Quote Link to comment Share on other sites More sharing options...
BioHazard Posted September 10, 2011 Author Report Share Posted September 10, 2011 I got her going, the bolt was just a little stiff rotating into the barrel extension but all is good now. I had to tap it in and out a few times then it slowly started to free up. Thanks for the advice... Quote Link to comment Share on other sites More sharing options...
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