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First time trouble shooting....... need some advice


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Now before the trolls and hate begin to rain down on me.. these are the parts I am having issues with.

PSA10 Gen3 lower

BCA 18" side charge upper

My sad discovery after opening the upper and placing it ever so joyfully on the lower , function checking the BCG to the rear ..... off slips my hand from the charge handle.

2nd attempt to pull BCG to rear , it doesn't move at all. (this happen a few times)

last attempt I reseat the upper and lower and it pulls back 3/4 the way only to stop again , at this point its clear of the FCG and the bolt release but will not pull back to lock. 


I don't currently have the photos to show it but there is a good 1 inch of slide space from where the BCG refuses to pull back and the upper housing.

I cannot think of anything that would keep this from happening other than the BCG is out of spec and is catching on something. Before I fire this thing and rip a hole in the upper or destroy the rifle completely I'd like to know if there is anyone out there that can think of something to try. I  have owned and built several ar15's but this is my first 10 build.

to note I wasn't worried about having the most awesome parts. I have 5 acres an a pretty decent hog issue from the cattle land next to me and the deer feeders on the land behind me. this was built just as a cheapo plinker. 


Thank you in advance, I hope out there in internet land someone may have some enlightenment for me (besides don't buy BCA because I'm not worried about a SHTF issue with this build)

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I believe I had seen your dissatisfaction on another post. Again don't really care about brands at the moment it was a cheap build. I am more or less interested in the functional issue if anyone has had a similar issue , it is still under their warranty as I just received it. If its a flaw with the BCG being out of spec or something I can just send it back.

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Update after measuring everything it's 30 coils 11 3/4 length it's a short buffer , the ID is 7inch . I removed both the spring and buffer and it barely pulls back far enough for the bolt catch to lock in. And I mean barely I have to force it back pretty good. I put the buffer and spring back in.

I noticed when I was trying to cycle it this morning it acted like it was hitting the buffer tube instead of going in so it wouldn't move the BCG at all. With the spring and buffer removed the BCG goes in 3/4 the way and feels tight so I may have a an issue with the buffer tube it's self or the bcg is milled slightly too large.


Any thoughts?

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From what I have learned from this forum is that 308 AR uppers and lowers are not always compatible brand to brand.  The common wisdom is buy the same brand upper as the lower because there is no real"standard" as there is in the AR15 world.

Your upper and lower is the first problem to fix, a suggestion get a PSA upper and go from there.

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Pictures of your problem can help greatly.  Please upload some when you get a chance.

Did you assemble the upper and lower?  Or were they factory assembled?

I had a similar issue with an AR I put together.  It ended up that I had bent the receiver extension when tightening it.  (Brute force is not always the way :lmao: )

1 hour ago, astx117 said:

it's a short buffer

What do you mean by short buffer?  A couple of sixteenths can make a difference.  Please provide an accurate measurement.

38 minutes ago, AzRon said:

308 AR uppers and lowers are not always compatible brand to brand

This is always sound advice when assembling LFARs.

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Welcome. Mixing PSA and BCA is probably not a good idea. I have 2 PSA guns and the uppers only fit the PSA lowers. The BCA upper I have fits both DPMS and Bushmaster Lowers. My best guess is the BCG isnt quite in line w/the receiver extension. As well as spring and buffer length problems. I replaced the entire buffer system on the PSA with the Armalite recoil system.


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After finally having the time to disassemble the upper and clean it and apply some lube it finally goes back far enough for the bolt catch. Not sure what changed there wasn't any wear marks on the bcg or upper receiver as if it was binding. Will comment again after barrel break in if it ends up doing the same thing. 

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"Welcome. Mixing PSA and BCA is probably not a good idea."


+2 and here's my .02 cents worth.

Sometimes "cross-breeding" uppers and lowers from different manufacturers works and sometimes it doesn't.  

I'd go right back to square one and obtain a PSA upper to complete the build.   PSA made several changes to their 308-AR components hence the Gen I, II, III etc.  I've built a number of each and used A2 stalks on all of them without issues.  I also obtained DPMS buffers/springs and they work fine with the A2 conversions.  I never fired any of them with the PSA 6 position stalks and related parts.  

I do remember playing around with non PSA uppers a couple of times trying to mate them to PSA lowers and ran into the same issue you are having with some slight "catching" when trying to fully retract the charging handle and lock the BCG to the rear.  It bothered me enough that I didn't proceed and try to fire any of them.

I did all of this before finding this site and still have a nice box of new parts left over as part of my "education"  when trying to complete several builds and doing some mixing/matching of components....etc.....

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Thanks for the heads up I think my next build I will piece It together with a matched upper and lower set. I found a ton of useful information here just in a short amount of time. Like I hadn't the slightest clue it would be so finicky about what works and doesn't compared to the ar15 platform.

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If you get thing working right, do a nice write up on it and it might save someone else down the road. A lot of things wind up working together, and a lot of things don’t. It’s impossible to have a full list of what will fly matched up with another brand…but having threads work through it just supply more data to the internet for those searching specifics later on. Some info is hard to find on here, but there’s been a lot of trial and error builds. Most of us on this forum have been through at least one of those. 

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