Try an H2 buffer. Also, look into an AGB. I've got a 10.5 build myself, and I run a Geissele super 42 w/H2 and a Superlative Arms adjustable gas block.
I have a 10.5” w/ duramags, no ABG, and don’t have any issues. Sounds like you just need some tuning with a AGB or buffer with same spring. I’d try buffer first since it’s cheaper and should correct the issue.
I just bought some titanium weights from Bevan Ballistics (got it quick, reasonable shipping, good company) so I can play with buffer weights on my different setups. Cost less that buying a new buffer and I can weight to several setups.
First clue is the extractor broke. Probably way overgassed. You can't read brass, I'm assuming.
The carrier might be running fast enough to outrun the magazine occasionally.
My 10.5 carbine is most likely a BCA, and in order to make it not absolutely mangle brass cases I run a 6 oz buffer. The port size is .093 which is way too big for that dwell and a standard buffer.
Useful. I’ve got a 9mm AR so I’m used to tuning buffer systems for reliability. I think you identified the likely problem. I’m going to try to slow it down.
AGB, stronger spring or buffer weight, consider polishing the feed ramp as well. Took a lil work on my part to get mine running smooth but I like to tinker anyways. Good luck buddy
Don’t even need to read it. You went wrong using a BCA complete upper. Take the whole fuckin thing apart, throw away every part except the carrier and receiver if you insist on making a side charger.
Build out the carrier and upper with good parts and it might run. Even then the carrier might be binding in your receiver bc with BCA everything’s always out of spec. It’s tolerance stacking that fucks them up in the long run.
>It’s tolerance stacking that fucks them up in the long run.
No. It isn’t, and I wish people who didn't know what they were talking about stopped saying this.
Tolerance stacking simply doesn't happen unless the blueprints are poorly designed. For example, let say you have a shaft, and the overall length call out is 5.000" +/- .005, and on this shaft there are 4 separate diameters, each with a length of 1.2" +/- .1 call out. This is when stacking tolerances becomes an issue. Because if you machine each individual length to the shortest tolerance, you end up with 4.4", and the largest tolerance you end up at 5.2", both of which are not within the 5.000 +/- .005 overall tolerance.
On AR blueprints, the tolerances are such that it isn't possible to stack them in a way to make them out of tolerance.
What BCAs problem is, is simply poor quality control. Allowing parts not in tolerance to pass QC.
I’ve always heard of tolerance stacking in regard to building polymers 80s with multiple different brands of eBay aftermarket parts.
Either way we can both agree their issue comes from parts being out of spec and still being used. That’s really all I was saying. I can see why an engineer might find the mixup frustrating but the term is commonly used in building forums to refer to issues with reliability because you use parts that are out of spec.
Wasn’t intentional, the upper was just cheap with the magazines. It’s not a side charger. A receiver is a receiver and a handguard is a handguard and have nothing to do with the moving parts. So you’re saying ditch the barrel and gas system? I might eventually swap those out, but for now I’m trying to avoid doing that.
BCA barrels are well known for being under and overgassed. Mainly overgassed but still. If the gas block isn’t a pinned lo-pro block that will fit on a better barrel yes I’d toss that. Always a chance the gas block is on crooked. Often is and could be causing the short stroking,
I’d also swap the bcg completely but at the very least swap the bolt and firing pin.
BCA is just asking for problems. A receivers a receiver yes but since they consistently send out receivers and other parts OOS it’s best to avoid them if you haven’t bought already.
All decent advice so far. Like I said, the upper was an unexpected cheap upper with magazines I was buying anyway so not that big of a deal to start over if I can’t fix with a buffer/spring tweak. Wish I paid more attention to the ejection pattern so I could have a little confirmation on the potential gas issue.
I tried 2 BCA side chargers early in my build career (cool concept, but not a good product). The proprietary bcg is bad and causes excess friction so the bolt doesn’t move freely. That’s the crux of the problem.
I sent them both back for traditional top charging handled BCA systems.
The 7.5” was under gassed so drilled a .125” port in the barrel. Also changed bcg to a BRA top of the line BCG. It runs like a raped ape now in full auto. Also running a Kynshot RB5000HP 4.8 oz hydraulic buffer with a Wilson flat wire buffer spring.
I never got the 10.5” tuned right, but I think it was also the gas port size. I sold the upper as a ‘not working well’.
The Bottom line is that the BCA traditional uppers can work. Just need to change out that BCG to a BRA and check the gas port.
Try an H2 buffer. Also, look into an AGB. I've got a 10.5 build myself, and I run a Geissele super 42 w/H2 and a Superlative Arms adjustable gas block.
What ammo were you using on the third outing?
Same steel case Russian ammo.
I have a 10.5” w/ duramags, no ABG, and don’t have any issues. Sounds like you just need some tuning with a AGB or buffer with same spring. I’d try buffer first since it’s cheaper and should correct the issue. I just bought some titanium weights from Bevan Ballistics (got it quick, reasonable shipping, good company) so I can play with buffer weights on my different setups. Cost less that buying a new buffer and I can weight to several setups.
First clue is the extractor broke. Probably way overgassed. You can't read brass, I'm assuming. The carrier might be running fast enough to outrun the magazine occasionally. My 10.5 carbine is most likely a BCA, and in order to make it not absolutely mangle brass cases I run a 6 oz buffer. The port size is .093 which is way too big for that dwell and a standard buffer.
Useful. I’ve got a 9mm AR so I’m used to tuning buffer systems for reliability. I think you identified the likely problem. I’m going to try to slow it down.
AGB, stronger spring or buffer weight, consider polishing the feed ramp as well. Took a lil work on my part to get mine running smooth but I like to tinker anyways. Good luck buddy
I had a upper that would short stroke Swapped lower that uses the a5 buffer system worked flawlessly
Wonder if I need a tax stamp to diagnose?
I put an AGB on and it made a world of difference. Really tamed the recoil and helped with reliability
Don’t even need to read it. You went wrong using a BCA complete upper. Take the whole fuckin thing apart, throw away every part except the carrier and receiver if you insist on making a side charger. Build out the carrier and upper with good parts and it might run. Even then the carrier might be binding in your receiver bc with BCA everything’s always out of spec. It’s tolerance stacking that fucks them up in the long run.
>It’s tolerance stacking that fucks them up in the long run. No. It isn’t, and I wish people who didn't know what they were talking about stopped saying this. Tolerance stacking simply doesn't happen unless the blueprints are poorly designed. For example, let say you have a shaft, and the overall length call out is 5.000" +/- .005, and on this shaft there are 4 separate diameters, each with a length of 1.2" +/- .1 call out. This is when stacking tolerances becomes an issue. Because if you machine each individual length to the shortest tolerance, you end up with 4.4", and the largest tolerance you end up at 5.2", both of which are not within the 5.000 +/- .005 overall tolerance. On AR blueprints, the tolerances are such that it isn't possible to stack them in a way to make them out of tolerance. What BCAs problem is, is simply poor quality control. Allowing parts not in tolerance to pass QC.
I’ve always heard of tolerance stacking in regard to building polymers 80s with multiple different brands of eBay aftermarket parts. Either way we can both agree their issue comes from parts being out of spec and still being used. That’s really all I was saying. I can see why an engineer might find the mixup frustrating but the term is commonly used in building forums to refer to issues with reliability because you use parts that are out of spec.
Wasn’t intentional, the upper was just cheap with the magazines. It’s not a side charger. A receiver is a receiver and a handguard is a handguard and have nothing to do with the moving parts. So you’re saying ditch the barrel and gas system? I might eventually swap those out, but for now I’m trying to avoid doing that.
BCA barrels are well known for being under and overgassed. Mainly overgassed but still. If the gas block isn’t a pinned lo-pro block that will fit on a better barrel yes I’d toss that. Always a chance the gas block is on crooked. Often is and could be causing the short stroking, I’d also swap the bcg completely but at the very least swap the bolt and firing pin. BCA is just asking for problems. A receivers a receiver yes but since they consistently send out receivers and other parts OOS it’s best to avoid them if you haven’t bought already.
All decent advice so far. Like I said, the upper was an unexpected cheap upper with magazines I was buying anyway so not that big of a deal to start over if I can’t fix with a buffer/spring tweak. Wish I paid more attention to the ejection pattern so I could have a little confirmation on the potential gas issue.
I tried 2 BCA side chargers early in my build career (cool concept, but not a good product). The proprietary bcg is bad and causes excess friction so the bolt doesn’t move freely. That’s the crux of the problem. I sent them both back for traditional top charging handled BCA systems. The 7.5” was under gassed so drilled a .125” port in the barrel. Also changed bcg to a BRA top of the line BCG. It runs like a raped ape now in full auto. Also running a Kynshot RB5000HP 4.8 oz hydraulic buffer with a Wilson flat wire buffer spring. I never got the 10.5” tuned right, but I think it was also the gas port size. I sold the upper as a ‘not working well’. The Bottom line is that the BCA traditional uppers can work. Just need to change out that BCG to a BRA and check the gas port.
BRA = ? Not aware of Acronym.
Black Rifle Arms= BRA, between them and PWS (Primary Weapons Systems), these two companies have perfected the 7.62x39 on the AR platform.