.308 BCG Jamming

[Jbyrd02]

I bought and built a .308 rifle kit from a website that does Buy, Build and Shoot Kits. (Yeah its a Polymer Lower) I assembled everything and started shooting, after about 35 rounds it got hot then seemed like it Short Stroked and the BCG got stuck. I couldn't pull the charging handle back, or release the BCG. It was really friggin stuck. So I waited about 30 minutes and was able to cycle it. Broke it down, checked functionality, lubed the BCG and Reassembled. I fired another 20 rounds then the same dang thing happened, BCG super stuck. Had to wait another 30 mins for it to cool down then I was able to cycle the BCG. It did not come with an Adjustable Gas Block and I don't see any fouling on the gas Tube. If anyone has experienced this problem or has a solution Please, Please help a guy out. I've built 4 AR's from the ground up. This is the first .308 build for me. Thanks Guys

[ar15barrels]

Try a different bolt carrier and see if the problem goes away.
Did you use a proper 308 dimensioned gas tube or just an AR-15 gas tube?

[Dr69er]

Which pattern is the rifle built-on: DPMS Pattern 308 or Original Armalite AR-10 Pattern 308 ?

If It is a Original AR-10 Pattern it does use a longer gas tube vs. the DPMS/SR25 Pattern which uses a AR-15 length gas tube...

Ditto for the Bolts as well, as there variations in bolt design/barrel extensions
between the two main patterns of AR 308's...

Bottom line is this: unlike the AR-15 pattern rifles the AR-10/AR-308 rifles are not Industry standardized and thus subject to a host of compatibility Issues, etc.

Good luck.

[liber]

If It is a Original AR-10 Pattern it does use a longer gas tube vs. the DPMS/SR25 Pattern which uses a AR-15 length gas tube...

This is not entirely true and has to do with the barrel as well. The OP really doesn't know what he has, he bought it from a vendor who supplied the entire kit to him, so asking what type of parts he has will be fruitless.

[ar15barrels]

Which pattern is the rifle built-on: DPMS Pattern 308 or Original Armalite AR-10 Pattern 308 ?

If It is a Original AR-10 Pattern it does use a longer gas tube vs. the DPMS/SR25 Pattern which uses a AR-15 length gas tube...

Ditto for the Bolts as well, as there variations in bolt design/barrel extensions
between the two main patterns of AR 308's...

AR-10 and LR308 bolts and barrel extensions are interchangable.
There is NO variation between the patterns in this respect.

The reason I mention gas tubes is that LR308's use an AR-15 gas tube, but you need to put more BEND into the tube.
Nobody thinks about this and the vast majority of LR308's are improperly assembled because of it.

[ar15barrels]

This is not entirely true and has to do with the barrel as well.

An Armalite AR-10 pattern rifle absolutely uses a longer gas tube than a DPMS LR308 pattern rifle.

[liber]

An Armalite AR-10 pattern rifle absolutely uses a longer gas tube than a DPMS LR308 pattern rifle.

I have a Criterion 308 Bull Barrel I just got, and they recommend the slightly longer 308 gas tube. I'm waiting on the upper to assemble it, but ordered the slightly longer gas tube from them when I ordered the barrel. It is DPMS pattern and going into an LR-308. The longer gas tube is the one they recommend and sell.

[ar15barrels]

I have a Criterion 308 Bull Barrel I just got, and they recommend the slightly longer 308 gas tube. I'm waiting on the upper to assemble it, but ordered the slightly longer gas tube from them when I ordered the barrel. It is DPMS pattern and going into an LR-308. The longer gas tube is the one they recommend and sell.

So you are using an AR-10 pattern barrel to build your LR308 gun.
No problem.
Just use the AR-10 gas tube they recommended you...

[Dr69er]

AR-10 and LR308 bolts and barrel extensions are interchangable.
There is NO variation between the patterns in this respect.

The reason I mention gas tubes is that LR308's use an AR-15 gas tube, but you need to put more BEND into the tube.
Nobody thinks about this and the vast majority of LR308's are improperly assembled because of it.

IIRC, the Bolt on the Armalite AR-10 varies with the DPMS version in that
they use different firing pins, the AR-10 uses a smaller firing pin/pin hole
and It also use a wider hammer slot on the bolt carrier and may also use
a different extractor size/type, but am not 100% on the extractor...

I believe the actual bolt teeth/pattern/and extension are pretty much the
same in that regard...I believe the same thread pattern for the barrel extension IIRC...(you most likely can recall better than I on what the
thread pitch is for the barrel extension is).

The Armalite AR-10 versions tend to be (or have) a better reputation for overall build quality and generally have a better factory warrantee vs. the
the DPMS versions (although the DPMS G2/GII having a lighter/Improved design over the original DPMS G1 currently).

The DPMS LR-308 (G1) Series do have a few advantages over Armatlite AR-10's in that they are generally less expensive but more Importantly they tend to
have more Industry support and parts availability...


Sorry for the short rant...

[ar15barrels]

IIRC, the Bolt on the Armalite AR-10 varies with the DPMS version in that
they use different firing pins, the AR-10 uses a smaller firing pin/pin hole
and It also use a wider hammer slot on the bolt carrier and may also use
a different extractor size/type, but am not 100% on the extractor...

I believe the actual bolt teeth/pattern/and extension are pretty much the
same in that regard...I believe the same thread pattern for the barrel extension IIRC...(you most likely can recall better than I on what the
thread pitch is for the barrel extension is).

The EARLY Armalite 308 carriers had the narrow hammer slot but this has not been the case the last 15 years.
Armalite 308 bolt carriers fully interchange with DPMS.
The firing pins are also interchange, though they are shaped differently.
The AR-10 just add a spring where the DPMS does not use one.



The bolts are fully interchangeable between the two standards.
The barrel extensions are identical including the threads.

[Jbyrd02]

Thanks for all the feedback. I did sone research and it looks like it's built in the DPMS pattern. I'll try a different bolt carrier and see if the problem is relieved. If not I'll change the gas tube.

[liber]

The EARLY Armalite 308 carriers had the narrow hammer slot but this has not been the case the last 15 years.
Armalite 308 bolt carriers fully interchange with DPMS.
The firing pins are also interchange, though they are shaped differently.
The AR-10 just add a spring where the DPMS does not use one.



The bolts are fully interchangeable between the two standards.
The barrel extensions are identical including the threads.

Thanks for all the feedback. I did sone research and it looks like it's built in the DPMS pattern. I'll try a different bolt carrier and see if the problem is relieved.

If not I'll change the gas tube.

That might be a better place for you to start. However, you should ask the vendor you bought it from and quit trying to second guess it. If they sold you the kit, presumably they know what works in their kit, so that's probably not it.

Honestly, you might think about taking it to the gunsmith that knows what they're doing.