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Posted: 4/12/2025 4:17:51 PM EDT
[Last Edit: Big0veralls][Edited]
| Hello everyone. I’m a newbie here and relatively new to the AR15 platform. I was hoping I could get some advice. I have a PSA AR-15 with a 16” .223 Wylde with a Strike industries King Comp muzzle break/flash suppressor, carbine length gas system and I assume carbine buffer, it’s not marked that I could tell. I changed the gas block when I changed the barrel to a low profile. It had an A2 front sight and gas block before. This problem happened with the original barrel also. It’s always done it. Not every round but multiples. Today I had probably 20 total FTF and six rounds that didn’t load all the way and the bolt struck and bent the casings. Also the bolt only locks open on the last wring in the magazine every once in a while. I was Shooting 55 and 62 grain rounds. Mostly AAC 55 grain fmjbt and black tips, and Ptac 62 grain greens tips. I’m thinking I need to up the buffer weight because it’s cycling too fast but I have no idea. Please somebody teach me something. My rifle was clean and lubricated before shooting today and I made sure not to get any oil in the holes in the bolt. |
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Problem in the gas block, with either the block gas port not aliened to barrel port, the block leaking at the barrel or gas tube, or did not index the gas tube to the carrier key correctly after the gas block was set/maybe barrel nut not installed correctly to the gas tube is not binding on it top tube void area or channel. So step one, pull gas block and go back and check barrel nut so it top void area for the gas tube, is dead center on the upper receiver channel for the gas tube. Also, barrel nut needs to be tightened to at least 30ftlbs, but no more than 80ftlbs. Lastly here, always check the barrel extension to make sure that center of top lug is center of gas tube channel, and that bottom area between feed lips, is centered on front take down lug. Here, the barrel has canted in upper receiver socket when barrel nut was tightened and needs to be corrected,  Next, break out a mic, and measure from back of gas block to center of gas channel in it, then do the same for the barrel shoulder to its center of gas port. In some cases, the block needs to be right against the barrel shoulder, while other times if the block is designed for front hand guard clip, then block need to be gapped off the barrel shoulder isntead. Next look inside the gas block at the gas passage and make sure there is not a ring around the entry channel that needs to be removed. The passage is drilled up from the front bottom set screw, and if any ring burs at the entry, will not allow the block to seat correctly against the barrel. From there, before you install the gas block to barrel, install the gas tube, pull the front set screw and look up the channel to make sure that gas tube side entry channel is centered on passage channel. If not, and dam sure that you did install the gas tube cross pin through the front of tube channel, not in front of the channel, then can use a drill bite up through the channel to enlarge the bottom channel in the gas tube, to make the gas blocks gas passage channel. Now before you install the gas block, mark the barrel shoulder with pencil, and us that line for center of gas tube out the back of gas block, to install the block to barrel (either against shoulder or gapped as needed. as for set screws, they get loctite in place with 272 loctite, and if you need to remove them at a later date, then soldering gun on the allen bolts to break the loctite before they are spun back out. Note, there are tools that will index off the center of barrel gas port, to countersink a indent in the bottom of the barrel for the front set screw in the gas block, but the pencil line once you know if the gas block has to be flush or gapped off, would just as well Now on gas tube index to key, remove bolt from carrier, and use just carrier in upper to check for aligment. If gas tube needs to be tweaked, then tube is tweaked/bent over the center of the barrel, not bent where it protrudes into the upper receiver instead. One last check, flood around the edges of the gas key on the top of the carrier, hold the bolt inwards, and with a air compressor set to around 100lbs of pressure, hold the bolt inwards, and pressurized the front of the key. Your going to leaks at the bolt with that pressure,but there should be no leaking from bottom of key to top of carrier. If carrier key is leaking to top of carrier, then key bolts need to be pulled and throw away, key bottom lapped to top of carrier, sealant applied to the two, new key bolt tighted to 27inchlbs, and the key metal re-flowed to side of bolt splines (or if right is new enough, just get manufacturer on the phone to resolve the leaking gas key instead). Same with the gas block front and back sides, and even at the gas tube coming out, with rubber tube on back of gas tube, to put 100lbs through the gas tube, so check for leaks of the gas tube to block, or block to barrel. Note, barrel gas port will allow air through it, but at 100psi down the tube, will be enough back pressure at the barrel gas port, to check for leaks at the block to barrel and gas tube to block. The only thing not mentioned at this point, is the barrel gas port size in the first place, which should be checked before the barrel is ever installed and even head space checked with bolt that is going to be used. For standard, none full time supressed rigs in 223. 11.5" barrel, .625: dia., 3.850" from muzzle; Port sizes from .081" to .089" 11.5" barrel, .750" dia., 3.850" from muzzle Port sizes from .086" to .094" 14" barrel, .625" dia., 8.375" from muzzle; Port sizes from .063" to .078" 14" barrel, .750 dia., 8.375" from muzzle; Port sizes from .070" to .086" 16" barrel, .625" dia., 8.375" from muzzle; Port sizes from .063" to 078" 16" barrel, .750" dia., 8.375" from muzzle; Port sizes from .070" to .086" 20" barrel, .625" dia., 8.375" from muzzle; Port sizes from .086" to .093" 20" barrel, .750" dia., 6.875" from muzzle; Port sizes from .093" to .096" 24" barrel, .825" dia., Port size .089" 20" 6.25" .093" 16" 8.50" .063" 14.5" 6.75" .067" 11.5" 3.875" .076" 10.5" ? .089" And to throw in, since post is becoming a novel anyways, do not clean the barrel or rifle with Hoppes, or any other solvent base product that is going to leave a protect film behind. You can use Sweets to remove the copper in the bore, but chamber being scrubbed by hand with chamber brush, and the rest of the rifle, CLP only!!! Hence CLP mixing with the protect film that Hoppes and other products leave behind, just becomes a stick mess in the chamber that is going to cause cycling problem in no time, and even worse at the chamber heats up. |
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'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...
<---skips away in frilly skirts to Candyland, leaving gutters and snorkels FAR behind.
'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...
<---skips away in frilly skirts to Candyland, leaving gutters and snorkels FAR behind.
Joined:
Apr 2025
Posts:
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TX, USA
Joined:
Apr 2025
Posts:
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EE: 0% (0)
TX, USA
| Alright, I checked the gas port. It measured .0645” with my calipers. I found a drill bit, 5/32 I believe that measured .077” and drilled out the gas port. Cleaned the barrel of the carbon and shavings from the port as well as the BCG. Just got back from the range and it seems that solved all the issues I was having. No cycling issues and the bolt held back on lest round every time. Thanks for all the help it really means a lot. Have a good Easter. Oh and the original barrel that came with the rifle I checked as well and it had the same size port at .0645 so that makes since why I had the same problem with it. |
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