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Posted: 11/17/2025 2:52:15 PM EDT
| I recently built myself an 80% AR and everything seems to be in working order except for one thing. The problem is I currently don't a semi-automatic rifle i have a single fire rifle. I can pull the charging handle to load the first shell and shoot it, but it doesn't even try to push back and reload itself at all. I can pull the charge handle again and it will eject it and load the next one just fine. I suspected it must be a gas problem but looked at that and made sure the holes lined up as well as I could and tried it again and same problem. I am fairly new in the AR15 realm so any help would be great trying to get it ready for coyote season! |
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Yeah sounds like a gas problem. My first thought is gas block alignment.... but if you say they are aligned I gotta believe you without pictures. What length barrel, with what length gas tube? Is it an adjustable gas block? Have you tried different mags and ammo? What kind of bolt? Have you looked at the gas rings on the bolt? When you extract a fired round is it sooty or mostly clean? Fire a round and look at the next round in the mag, sooty or clean? |
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Yes, I believe it lined up the best I could. I will try to get some pictures today. It's a 20-inch barrel the whole upper parts came together as a kit I just put it together. I don't think it's an adjustable gas block but i would have to double check. I have tried 3 different types of ammo and two different mags. I haven't taken the bolt out since I installed it but just from looking through the mag hole and ejection port it looks normal. I did see a small line of soot on the next bullet when I ejected it, but it looked more like dirty oil just off the bolt. I bought the KM Tactical 20 in full kit minus the lower. This is the description. 20″ 5.56 Complete Kit (Minus Lower) 20 Inch 5.56 Marksman Upper (Unassembled) Standard Upper Receiver w/ Forward Assist & Dust Cover 17″ Mlok Rail Standard 1/2×28 A2 Flash hider 20″ 5.56/223 Barrel Chrome-Moly Lined Rifle length gas system .750 at the shoulder Nitride BCG/Standard Charging Handle Standard Lower Parts Kit Fixed A2 Stock Assembly |
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Originally Posted By copperbeans: I did see a small line of soot on the next bullet when I ejected it, Post a pic of the inside of the upper receiver where the gas tube comes in. Maybe they put a mid-length tube in it by mistake. If it's the right length, it should come into the receiver far enough to line up with the curved channel that the cam pin rides in. |
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Originally Posted By dogrobber13: Jesus! I thought i was the only one! Originally Posted By dogrobber13: Originally Posted By HeavyMetal: Make sure the gas tube isn’t upside-down. Jesus! I thought i was the only one! I haven’t, but others have. |
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| If it doesn't push back at all I'd be suspicious of something more that undesized gas port. Loose gas key,bad rings, bad GB alignment... something is severely out of spec to have no appreciable attempt to cycle. Could also be death but a thousand cuts... everything is a little bad but, that's not usually the case with new components. |
| Not just an upside down gas tube, but make sure you don’t have the gas tube roll pin in FRONT of the gas tube instead of going through it. We’ve seen that here dozens of times! |
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