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panel77

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BCA are good people!  They have it - they know what's going on.  On an 18" midlength gas .308 barrel with a .750 gas block diameter, you need 0.081" to run it, on the small side.  I took one up to 0.085" to make it reliable with anything.

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Rainier followed through with speed and excellence.

The correct length tubes arrived and are 12.0x

Did some super redneck milling on the trash PSA upper so I could use it if I wanted to to gain the clearance on the upper to allow the mag to fully seat easy up into the upper.

now to find some ammo to send downrange.

Might be a while

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On 1/27/2019 at 10:26 AM, 98Z5V said:

BCA are good people!  They have it - they know what's going on.  On an 18" midlength gas .308 barrel with a .750 gas block diameter, you need 0.081" to run it, on the small side.  I took one up to 0.085" to make it reliable with anything.

The BSA noted is rifle length gas system

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1 hour ago, panel77 said:

The BSA noted is rifle length gas system

BCA - not BSA.   No, it's not- not the one you linked.  It's a midlength gas system, by description, and by the picture of the barrel they posted.  Check what you posted again...                                                                                                                                                                                                                                                                                                                                                              

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  • 1 month later...

Shot it yesterday.

Got 3-4 mags(10rnd) through it before near teh end of one mag, the bolt rode over the bullet as bullet was feeding.

wasnt the mag.

tried single slow shots and rapid fire-didnt make difference.

MIGHT chalk it up to ammo(cheap bulk) but...

it did better after;

proper length gas tube

port to .0785

long spring

5.4x buffer

2 quarter stack

 

ran out of full mags and was 50 miles from the ammo can...

ideas before i run another $40 through it?

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  • 4 weeks later...

Shot it after doing all that stuff

= fail

threw away all that work and time and parts money.

bought 18" bear creek complete upper w/BCG...

came quick and nice and lubed all to heck-great.

got 2 rounds through it before bolt rode over round and jammed.

took it to gunsmith, he got excite and took the A2 upper I had with all teh PSA fixes on it and reamed that gas hole out to #40=.096

nope

first round bang, second round stack.

 

so its not teh upper, not the upper parts, not anything to do with upper... what is it?

BTW, have 2 complete lower setups. one from AMT and other unknown in raw from gunsmith but ALL dimension match AMT....

HOWEVER, I measured a poly 80-10 and there is ONE difference between the lowers.

 

the poly 80 mag catch is 0.661 from upper edge of mag catch slot to top of lower, the other 2 lowers are 0.695 also ordered one from blitzkrieg and they get them from same place as AMT and if i can ever get them to reply to my email or phone calls-returning it, dont need 4 of the same useless brick.

 

so next will be to take all the uppers out and borrow the poly 10 and see what happens.

if anyone has a 10-can you measure from top of lower to top of mag catch slot?

thanks

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  • 2 weeks later...

Midlength gas system? Gas tube would be around 12-ish inches long, eye-balling with a tape measure?

 

Nevermind- -  I read the whole thread again - but which upper are we talking about in this recent pic?  The BCA or the PSA (the one in the pic above)?...

It's gotta be midlength gas - there aren't too many manufacturers brave enough to try making an 18" rifle-gas barrel. 

Edited by 98Z5V
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Just a couple of thoughts on this. I have 1 load that sometimes doesn't cycle the action all the way on my PA10. It just happens to be a load my bolt gun loves. If you are using just 1 type of ammo try switching to a different round. Before doing all the work on the mag catch why don't you try modifying 1 magazine. Add some jb weld etc to the top of the notch and remove a bit from the bottom of the area so it moves the mag up some. If this solves the problem then look at modifying the mag catch and the work on the lower that that would entail.  A lot easier to modify the 1 mag to see if moving the mags up solve the problem. Just a thought.

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On 4/10/2019 at 11:05 PM, 98Z5V said:

Midlength gas system? Gas tube would be around 12-ish inches long, eye-balling with a tape measure?

 

Nevermind- -  I read the whole thread again - but which upper are we talking about in this recent pic?  The BCA or the PSA (the one in the pic above)?...

It's gotta be midlength gas - there aren't too many manufacturers brave enough to try making an 18" rifle-gas barrel. 

upper in this pic is the BCA....

not excited about breaking the seal on a brand new upper to blueprint it and hope i dont screw it up putting it back together.-most importantly aligning the gas block properly.

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On 4/11/2019 at 2:33 AM, shooterrex said:

Just a couple of thoughts on this. I have 1 load that sometimes doesn't cycle the action all the way on my PA10. It just happens to be a load my bolt gun loves. If you are using just 1 type of ammo try switching to a different round. Before doing all the work on the mag catch why don't you try modifying 1 magazine. Add some jb weld etc to the top of the notch and remove a bit from the bottom of the area so it moves the mag up some. If this solves the problem then look at modifying the mag catch and the work on the lower that that would entail.  A lot easier to modify the 1 mag to see if moving the mags up solve the problem. Just a thought.

thats a real good thought-will have to dig and see if diff ammo works BUT..... if the overall system is that finicky, its showing a glaring error that should be corrected.

having a tool that only works in your left hand in the sun on a tuesday is no longer a tool, its a picky, finicky, temperamental useless decoration.

SKS eats everything

870 eats everything

10/22 eats everything

ar15 eats everything.

DPMS10 SHOULD eat everything.

not talking about accuracy-im SURE various loads will improve that function for sure!

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10/22s don't usually like 36gr hollowpoints. I'm just sayin'...  :laffs:

We can fix the gun, with information.  Don't worry about that part, man.  I'll try to get these things I have here measured up for BCG centerline above top-of-mag-catch this weekend.  That's the only place I know to start, IRT the recent conversations. 

EDIT - gas block alignment is easy.  I can talk you through that. Have no fears on that.  :thumbup:

Edited by 98Z5V
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We gotta find the thread from @Lane on his build.  We mashed up numbers from different guns to find the solution, and it worked like a charm on his machining work. 

 

Found it - this is the thread:

 

Edited by 98Z5V
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  • 2 weeks later...
On 4/22/2019 at 11:52 PM, panel77 said:

broken arm 80% lower

mostly CMMG off shelf LPK

top of mag slot to top of upper-0.6665

buffer tube 7.00"

spring 13.5"

buffer 5.4 oz, 

BCA 18" assembled upper with teh still too short gas tube.

 

10 minute range day tuesday

so i failed to edit this properly before it posted-IGNORE the buffer tube length-it was measured WRONG.

IGNORE THAT NUMBER

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broken arm 80% lower

mostly CMMG off shelf LPK

top of mag slot to top of upper-0.6665

13.5" spring

5.4 buffer (same length as ar15 buffer)

7.75 buffer tube

BCA 18" assembled upper with the still too short gas tube.

-----

no malfunctions at all with about 100 rounds. 

-

swapped to teh A2 PSA upper with correct length gas tube, upper that matches teh AMT lower, and the gas port drilled to 096...

BIG MISTAKE.

shoulda taken pictures.

if the spent shell casing was tapered at both ends, it would have PERFECTLY loaded itself.

180' flip so open mouth facing bolt. more than 1 time.

gotta put an adjustable gas block on that one now.

im SURE the opened up too much port is the problem.

BUT.... the BCA assembled, out of the box upper with too short gas tube and unknown port size performed EXACTLY like it should and how i EXPECT it should have in teh first place.

 

the AMT lower with 0.95x space between mag catch and upper was WRONG compared to this 0.66x and I am FULLY convinced that the lower is the problem.

 

BUT.... that being said, every single lower will get the exact same specs-same buffer, tube, spring

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2 hours ago, 98Z5V said:

 5.4oz carbine buffers won't work on a 7.000" receiver extension, as aon off-the-shelf part. What's the length on that 5.4oz buffer?

ignore-failure to edit in time for accuracy, it apparently posted a draft....

buffer tube is PSA 7.75 and since nobody anywhere lists lengths on tubes, i will have to crawl back to PSA and wait for in stock and being charged market rate...

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20 hours ago, panel77 said:

swapped to teh A2 PSA upper with correct length gas tube, upper that matches teh AMT lower, and the gas port drilled to 096...

BIG MISTAKE.

 

See if you have any damage on the ears of your lower, from the BCG impacting it.  The internal depth on the receiver extension is too long, at 7.750" internal.  It should be 7 5/8" internal depth.  That enough of a difference to makethe BCG smash the ears on the lower - I'm curious if yours did.

 

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On 4/24/2019 at 2:14 AM, panel77 said:

ignore-failure to edit in time for accuracy, it apparently posted a draft....

buffer tube is PSA 7.75 and since nobody anywhere lists lengths on tubes, i will have to crawl back to PSA and wait for in stock and being charged market rate...

Don't go back to PSA. They don't know (don't care??) what the difference is between AR-15 and AR-10 or .308 AR buffer systems.

One-shot solution to your buffer tube/buffer/spring problem, right here: https://www.armalite.com/product/ar10rekit01-6-position-receiver-extension-kit/

Yeah, it's $55, and you've already spent an untold amount of money un-fvcking a PSA hack-job, but *that* setup ^ will get you where you need to be, at least as far as the recoil system is concerned. Don't swap parts with what you've got, install it exactly the way it comes out of the bag.

Edited by COBrien
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50 minutes ago, COBrien said:

Don't go back to PSA. They don't know (don't care??) what the difference is between AR-15 and AR-10 or .308 AR buffer systems.

One-shot solution to your buffer tube/buffer/spring problem, right here: https://www.armalite.com/product/ar10rekit01-6-position-receiver-extension-kit/

Yeah, it's $55, and you've already spent an untold amount of money un-fvcking a PSA hack-job, but *that* setup ^ will get you where you need to be, at least as far as the recoil system is concerned. Don't swap parts with what you've got, install it exactly the way it comes out of the bag.

55 isnt a bad price for what you are getting. and i try to keep groups together they way supplied from me until something screws up.

I agree about PSA-10

i will say the 15 has been flawless.

but i think in general i would prefer to NOT support PSA... 

 

they were the first cheap option i found and at teh time, i was on an insanely "dont tell teh wife" budget. things are slightly better now but with the combo with bear creek working now-im gonna stick with that and fiddlebump the rest as i get time and money and availability.

thank you!

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