FullySemiJamomatic Posted April 8, 2022 Report Share Posted April 8, 2022 (edited) I just finished putting together an Aero Precision M5 build and it is having some issues. When it does eject it dribbles out, if it ejects with any kind of speed (rarely) it is 1-2 o'clock but most times it will either spin the empty cartridge and then the BCG will pin it against the ceiling or the next round will pin it. I've spent a few days reading and the only thing I can come up with is I should try swapping the buffer and spring to an armalite brand? I thought going full Aero Precision would help fill the gaps of my lack of knowledge on the large frame ar platform but I missed something, any help or guidance is appreciated. Also, I read about the 2 o-rings on the extractor so I removed one but it didn't help. I have some videos of it shooting if that would help at all. Also, something weird I've noticed it may be short cycling because it doesn't lock back hard on the empty magazine sometimes. When I pick it up and drop the empty magazine, sometimes that is enough to slam the BCG forward. Parts list below: Aero Precision M5 .308 Rifle Buffer Kit: Buffer Length: 5.3” Buffer Weight: 5.6 oz. Complete M5 Assembled Upper Receiver: 18" .308 CMV Barrel, Rifle Length, Low Profile Gas Block and Rifle Length Gas Tube Aero Precision 308/7.62 Bolt Carrier Group Black Nitride Aero Precision M5 Lower and Lower Parts Kit Radian Raptor Charging Handle Luth-AR MBA-1 Stock VG6 Precision Gamma 762 Muzzle Brake Edited April 8, 2022 by FullySemiJamomatic Quote Link to comment Share on other sites More sharing options...
Armed Eye Doc Posted April 8, 2022 Report Share Posted April 8, 2022 Welcome to the forum. I doubt that your buffer is the issue. It is correct length and weight for a rifle buffer. A common issue with barrel manufacturers is drilling a gas port that is too small. That would be the next place I would look. There should be other advice coming in the near future. Also, how many rounds do you have through the gun? What kind of ammo? Quote Link to comment Share on other sites More sharing options...
Lonewolf McQuade Posted April 9, 2022 Report Share Posted April 9, 2022 Welcome from Pennsylvania!! Almost shlt myself laughing at your screen name 😂🤣 Quote Link to comment Share on other sites More sharing options...
unforgiven Posted April 9, 2022 Report Share Posted April 9, 2022 Welcome from Indiana brother Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 9, 2022 Report Share Posted April 9, 2022 (edited) Gas port on that rifle-gas 18" barrel with a 0.750" gas block journal needs to be 0.095" or right around there, or it's not gonna function properly. Measure your gas port diameter with numbered drill bits (they work best, have the best range). The gas port is the problem here. Also - buffer length should be 5.200" long. If it's really 5.300" long, shave/sand that bumper on the end of it to get it to the correct length. Make sure you're running this gun WET. Edited April 9, 2022 by 98Z5V Quote Link to comment Share on other sites More sharing options...
FullySemiJamomatic Posted April 9, 2022 Author Report Share Posted April 9, 2022 Thank you everyone for the replies and the greetings! I'm using Wolf 145 Gr FMJ (yeah, not the best) but figured I'd break it in with that; I have a bunch of Hornady 150 Gr and Federal 308 180 Gr hunting ammo that I can test with. Only about 15-20 shots so far but will use any excuse to get down to the range for "testing". 98Z5V, I just got finished reading one of your in-depth posts on balancing a timing system; it was all very helpful. Everything is definitely wet, to the point it was almost embarrassing at the range. The bolt felt sticky so I just cleaned it and wet the inside of the BCG and bolt even more then put more into the side of the BCG once together. I just measured the buffer with a caliper, you called it 5.3" long. I'll work on shaving the bumper tonight and will get a measurement on the gas port on the barrel tomorrow. Out of curiosity, does this look weird to anyone? I'm surprised to see carbon stains on the outside of the tube after only 15-20 shots. My AR15 has nothing there after 100-150 shots. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 9, 2022 Report Share Posted April 9, 2022 6 minutes ago, FullySemiJamomatic said: I just measured the buffer with a caliper, you called it 5.3" long. I'll work on shaving the bumper tonight and will get a measurement on the gas port on the barrel tomorrow. Out of curiosity, does this look weird to anyone? I'm surprised to see carbon stains on the outside of the tube after only 15-20 shots. My AR15 has nothing there after 100-150 shots. Before you cut the bumper, check the internal depth on the receiver extension. Rifle receiver extensions are 9 11/16" deep. Bury the tape down to the bottom, measure at the top of the extension, by the top of the lower receiver ears. Carbon fouling will happen - it always happens. Carbon fouling from the gas tube to gas block, and gas block to the barrel. Once the carbon seal is made, then the gun shoots better, once sealed. This is completely normal. Quote Link to comment Share on other sites More sharing options...
FullySemiJamomatic Posted April 9, 2022 Author Report Share Posted April 9, 2022 This one is just shy of 9 11/16, a little longer than 9 5/8 though. More like 9 21/32 at best? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 9, 2022 Report Share Posted April 9, 2022 You'll definitely need to cut the bumper, and bring that total buffer length to 5.200". Grind it, sand it, just get it to 5.200" overall length. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 9, 2022 Report Share Posted April 9, 2022 (edited) These things aren't that fucking complicated. I don't understand why manufacturers are "making it complicated" for us. There's already a "set pattern", and it the Knight's SR-25 Rifle. Which is the original Armalite AR-10. For fuks sake. I don't get it. My own rule - Don't complicate shiit with complicated shiit. It never works, in the long run. Edited April 9, 2022 by 98Z5V Quote Link to comment Share on other sites More sharing options...
FullySemiJamomatic Posted April 9, 2022 Author Report Share Posted April 9, 2022 I've had the armalite buffer kit link up all day expecting to be told I'd need to buy it, so sanding something 0.1" down is no sweat. Drilling the gas port on the barrel, I'd be less happy about for sure. Quote Link to comment Share on other sites More sharing options...
DNP Posted April 9, 2022 Report Share Posted April 9, 2022 The drilling is an easy fix if it comes to that. All you need is a hand drill, a couple drops of oil and a wood dowel if you want to put a safety net inside the barrel for when you pop through. I am not mechanically inclined and I wouldn’t be afraid to do it after all the times I’ve seen it done here. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 9, 2022 Report Share Posted April 9, 2022 ^^^ What he said. I've done this a bunch of times, whilst receiving barrels from great companies, that don't have their gas ports up to snuff. Punching up a gas port is really a no-brainer, and it's not hard at all. It's WAY EASIER to just do this, instead of sending it back to a compamy, and they give you a "fire report" that says "They didn't see anything out of the ordinary - gun functioned fine" - when it really doesn't. Measure your gas port. Drill your gas port UP if it doesn't measure what I stated. Once you do that, the gun WILL run. Quote Link to comment Share on other sites More sharing options...
FullySemiJamomatic Posted April 9, 2022 Author Report Share Posted April 9, 2022 I'll definitely drill it myself before I bothered with sending it across the country. I've been working on/modifying cars for about 16 years so I wouldn't said I'm worried about modifying it but I feel like if I bought all of the parts from the same manufacturer then all of the parts should have worked together in the first place and I shouldn't have to take a drill to the barrel. It would be like buying a car just to find out it wasn't engineered for the parts to work together... nevermind I own some of those too. If I drill it, do I have to blue the bare metal or doesn't matter? Going to try to take care of this all tomorrow morning and hit the range. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 9, 2022 Report Share Posted April 9, 2022 44 minutes ago, FullySemiJamomatic said: If I drill it, do I have to blue the bare metal or doesn't matter? Going to try to take care of this all tomorrow morning and hit the range. Nope, punch it. Open it up. If you think you'll worry about a burr in it, or something else, the first or second round down the barrel will eliminate that burr. Open it up. Quote Link to comment Share on other sites More sharing options...
FullySemiJamomatic Posted April 9, 2022 Author Report Share Posted April 9, 2022 Thank you for all the help! I shaved the buffer down to 5.20" and the gas port was small (about .088) so I drilled it open to .09375; it was the closest bit that I had but will order the correct .095 bit if it still acts up. Going to the range tomorrow to see how it goes and will post back with an update. Quote Link to comment Share on other sites More sharing options...
FullySemiJamomatic Posted April 12, 2022 Author Report Share Posted April 12, 2022 Thank you 98Z5V, it worked great! Before it would either dripple out, not eject at all or eject at the 1-2 o'clock. Now it forcefully ejects at the 3:30-4 o'clock every time. Not a single jam yesterday even with the bulk wolf ammo. Now they are ejecting fast enough to hit or go over the trash barrel on the other side of the table. Quote Link to comment Share on other sites More sharing options...
shooterrex Posted April 12, 2022 Report Share Posted April 12, 2022 Good to hear it is running well. Quote Link to comment Share on other sites More sharing options...
DNP Posted April 12, 2022 Report Share Posted April 12, 2022 (edited) Another satisfied customer of the “voodoo” numbers that just seem to work. I love the guys that come in here and call BS when they’re told the same thing. Glad she runs. Edited April 12, 2022 by DNP Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 12, 2022 Report Share Posted April 12, 2022 2 hours ago, FullySemiJamomatic said: Thank you 98Z5V, it worked great! Before it would either dripple out, not eject at all or eject at the 1-2 o'clock. Now it forcefully ejects at the 3:30-4 o'clock every time. Not a single jam yesterday even with the bulk wolf ammo. Now they are ejecting fast enough to hit or go over the trash barrel on the other side of the table. This story makes me happy - more than you know. Excellent work. Quote Link to comment Share on other sites More sharing options...
FullySemiJamomatic Posted April 12, 2022 Author Report Share Posted April 12, 2022 Here is a before and after if anyone is interested. Its a pretty dramatic difference. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 12, 2022 Report Share Posted April 12, 2022 I like it. I'd call it fixed. Quote Link to comment Share on other sites More sharing options...
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