wdlong1 Posted January 3, 2013 Share Posted January 3, 2013 I am having all of the symptoms of under gassing. I am getting a lot of bolt over base malfunctions, double feeds, and the bolt won't lock back on a empty mag when firing. The gun is completely new. Non-adjustable Gas block Mid length Mil Spec Bolt Buffer is aluminum and Buffer spring is supposedly mil spec Since the Gas system is mil spec, I am leaning towards the aluminum buffer being too light and the bolt is cycling too fast. Anybody agree....disagree? Anything else to check? What weight buffer should I go with? Thanks, Link to comment Share on other sites More sharing options...
kellymc Posted January 3, 2013 Share Posted January 3, 2013 (edited) I had one doing that the other day. The rifle was to dry to run the Wolf ammo.Reoiled the bolt and for insurence I cut 2 coils off of the recoil spring . Works fine now. Try oil first Edited January 3, 2013 by kellymc Link to comment Share on other sites More sharing options...
wdlong1 Posted January 3, 2013 Author Share Posted January 3, 2013 Yeah, oil was the first thing i did. Coated the bolt parts thoroughly...still same outcome. Link to comment Share on other sites More sharing options...
Steve RA Posted January 3, 2013 Share Posted January 3, 2013 Could be a leaking gas block, how is it attached ?? Link to comment Share on other sites More sharing options...
Alaskapopo Posted January 4, 2013 Share Posted January 4, 2013 Follow the gas system backwards starting at the gas port. 1. make sure the gas tube retaining pin is in place. I had a department gun from DPMS come from the factory with this part missing. 2. move back to the gas key see if its loose. Many companies don't stake the bolts on the gas key and they work loose with enough time. 3. check the gas rings see if they are all there and none are broken. Also check and see if they are worn. take the bolt out of the carrier remove the misc parts and insert the bolt back into the carrier by itself. pull it out and then set the bolt on a table with the carrier on top of it. If the bolt goes back inside the carrier under the weight of the carrier you need new gas rings. Also try some different ammo. White box Winchester is a great standard to use for function checking. Pat Link to comment Share on other sites More sharing options...
caspian guy Posted January 4, 2013 Share Posted January 4, 2013 What kind of ammo were you using? Link to comment Share on other sites More sharing options...
3gungeezer Posted January 4, 2013 Share Posted January 4, 2013 Did you build it? If so did you leave a gap between behind the gas block. Gas blocks are designed to have the plate that holds the front of the non free float handguards between it and the larger machined area behind the gas block. if not move the gas block toward the muzzle about a 1/16". It usually doesn't matter but I had one I built that required me to do this to get the gas holes to line up. It was a mid length build also. Link to comment Share on other sites More sharing options...
Alphamikefoxtrot Posted January 4, 2013 Share Posted January 4, 2013 Yes, I built it. This is my fourth build. The others were flawless. I will check the gas system again after dinner. I didn't leave a gap at the gas block. I will remove it and see what the gas ring looks like. the bolt only has 20 or so rounds on it. I can;t believe that parts could be worn out yet. Those rounds were the Hornady factory zombie rounds. I also tried some handloads and they did the same thing. Link to comment Share on other sites More sharing options...
3gungeezer Posted January 4, 2013 Share Posted January 4, 2013 Yeah, verify that the gas holes are lined up sounds like an under gas issue Link to comment Share on other sites More sharing options...
Alphamikefoxtrot Posted January 4, 2013 Share Posted January 4, 2013 Gas holes were lined up under the gas block. Bolt carrier wouldn't slide down on the bolt when I performed the test mentioned above. Key is properly staked and firmly mounted. Gas tube retaining pin in the gas block was there and firmly mounted with the hole in the gas tube facing the right direction. I am really miffed now. Link to comment Share on other sites More sharing options...
wdlong1 Posted January 4, 2013 Author Share Posted January 4, 2013 Thanks for the help AMF. My buddy has been over here helping and we are both stumped. Link to comment Share on other sites More sharing options...
blue edge Posted January 4, 2013 Share Posted January 4, 2013 Try a different BCG Link to comment Share on other sites More sharing options...
mic2377 Posted January 4, 2013 Share Posted January 4, 2013 Don't necessarily conclude that your gas system is "mil-spec." While a gas block is a simple and non-glamorous part, I have had them cause problems on several occasions, they are not a part to cheap out on. I have a thread on how a Kies block was leaking so badly my AR would not run correctly, and it exhibited similar symptoms. Also avoid "Black Dawn Ordnance" blocks. I had one that leaked evern worse than the Kies. Also, why not try a proven parts combination? Instead of cutting coils or using an aluminum buffer, try a standard GI spec spring and CAR buffer. Lube it up nice and wet and repeat testing. Link to comment Share on other sites More sharing options...
wdlong1 Posted January 4, 2013 Author Share Posted January 4, 2013 It is a standard buffer and spring. The buffer is aluminum with some kind of weights in it. I bought a mil spec kit that had the buffer tube, castle nut, end plate, buffer and spring in it. I am going to try a bolt carrier out of another gun in it this weekend. Link to comment Share on other sites More sharing options...
Mickster Posted January 4, 2013 Share Posted January 4, 2013 I went through much of the above to fix the failures to eject/lock back with no luck. Before going to the last resort of drilling out the gas hole until it would work I tried one more thing. Took a cleaning mop soaked with rouge/polishing compound, stuck it in a drill and polished the chamber thoroughly. Problem solved. What was happening was as the gas got to the carrier, the fired case was still under the effect of chamber pressure against the rough chamber just enough to use up the gas energy needed to function the rifle properly. It takes 20 minutes and costs almost nothing. Link to comment Share on other sites More sharing options...
392heminut Posted January 4, 2013 Share Posted January 4, 2013 Check and make sure you're not getting bolt bounce, which is caused by the bolt coming back too fast and coming back forward before the next round in the magazine can come up enough for the bolt to catch it. I had that problem with my son's rifle and an IMR-4895 load. The way to check it is to load one round in the mag and shoot it. If the bolt locks back you're experiencing bolt bounce. If it doesn't lock back then the gun is short stroking. Link to comment Share on other sites More sharing options...
3gungeezer Posted January 7, 2013 Share Posted January 7, 2013 Fixed??? Link to comment Share on other sites More sharing options...
wdlong1 Posted January 7, 2013 Author Share Posted January 7, 2013 When I disassembled the gun the other night I noticed that one of the set screws in the gas block was missing. I assume that it was loose enough to let some gas escape out from under it. I replaced the set screws and shot it. The first round malfunctioned with the fired round and the new loaded round were both trying to get into the chamber. After that first round after disassembly everything went perfectly for maybe 60 rounds. Maybe it is all good now. I wish it hadn't malfed that one time though. Link to comment Share on other sites More sharing options...
EkuJustice Posted January 7, 2013 Share Posted January 7, 2013 On the gas block, one way to help with that is to dimple the barrel for the set screws to have a little more to hold to. It is also a good idea to use loctite when installing the screws. Another way is to sent it to someone like adco or a smith and let them install a pin through the gas block to make it pinned then it is NOT going to move on you unless you remove the pin. My favorite is if the barrel comes with a front sight is cutting the tower off and using it as a pinned low profile. Its cheap and the most secure Link to comment Share on other sites More sharing options...
Steve RA Posted January 7, 2013 Share Posted January 7, 2013 Or get a clamp on gas block. Link to comment Share on other sites More sharing options...
MarkCO Posted January 7, 2013 Share Posted January 7, 2013 Damage to barrels, leaking and set screws backing out are the reasons we came out with our gas block. Pinning it removes the benefit if being able to use it again, clean it, etc. Link to comment Share on other sites More sharing options...
Boxer1 Posted January 7, 2013 Share Posted January 7, 2013 I had to adjust the posistion of my gas block on one of my rifles to get it to cycle the gas port just was not lined up enough I guess. It ran fine after the slightest of movement. Link to comment Share on other sites More sharing options...
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