Powder Residue on SLR Gas Block?

TheRussianNightmare · Dec 18, 2017

My 308 AR has a SLR Adjustable Gas Block. Is it normal for powder residue to end up on the front of the gas block, around the adjustment screw? I never noticed it before and I think it may be a problem.

I was shooting cheap 308 - 145 Grain FMJBT - Prvi Partizan. I had to open up the adjustment screw a few turns to get the ammo to cycle smoothly, and reliably. When I was done, I noticed a good bit of powder residue. I will post a pic later.

John from MD · Dec 18, 2017

The carbon build up will stop the small leakage in due course. If your rifle is cycling properly, don't sweat it. Disregard if you have backed the screw out to where only a thread or so is holding it in the block. :rolleyes:

thomfantomas · Dec 18, 2017

Cheap? Prvi Partizan is pretty good ammo dude

TheRussianNightmare · Dec 18, 2017

thomfantomas said:
Cheap? Prvi Partizan is pretty good ammo dude

Really? I got 500 rounds from PSA for about $0.50 a round. I am not that impressed with it.

thomfantomas · Dec 18, 2017

TheRussianNightmare said:
Really? I got 500 rounds from PSA for about $0.50 a round. I am not that impressed with it.

I never had any issues with the ammo :shrug:

TheRussianNightmare · Dec 18, 2017

John from MD said:
The carbon build up will stop the small leakage in due course. If your rifle is cycling properly, don't sweat it. Disregard if you have backed the screw out to where only a thread or so is holding it in the block.

The adjustment screw is probably pretty close to fully open. Brass kept getting stuck half way out of the ejection port. Opening it up helped a lot, but it still jammed occasionally. I am using DPMS bolt carrier, DPMS rifle buffer tube & spring, with DPMS 308 rifle buffer as well.

TheRussianNightmare · Dec 18, 2017

thomfantomas said:
I never had any issues with the ammo

I was having some cycling issues with it, but it may be a combination of gas block, carrier, buffer, and buffer spring. I don't know.

thomfantomas · Dec 18, 2017

TheRussianNightmare said:
I was having some cycling issues with it, but it may be a combination of gas block, carrier, buffer, and buffer spring. I don't know.

Id suspect something enternal not the ammo,isnt like you were using tula or wolf.

clandestine · Dec 18, 2017

It's 100% normal. The gas leakage will clot and reduce greatly over time as it's shot. Clamp-On models leak much less.

If you clean after each time you shoot, you will undo the clotting of the carbon and the large volume of gas leaking will never end. It will always leak gas even when fouled but not nearly as it does when new.

Gas leakage is ok though.

For instance if you have an AR with a fixed gas block that is properly gassed and install an adjustable gas block, it's quite likely that the gun will have cycling issues unless you open the gas port or go with a lighter buffer. Many people are not aware of this.

inkd · Dec 18, 2017

TheRussianNightmare said:
I was having some cycling issues with it, but it may be a combination of gas block, carrier, buffer, and buffer spring. I don't know.

Were you having cycling issues with it from the beginning and changed to an SLR gas block?

John from MD · Dec 18, 2017

My question also. Are you planning to run a can?

TheRussianNightmare · Dec 18, 2017

clandestine said:
It's 100% normal. The gas leakage will clot and reduce greatly over time.

If you clean after each time you will undo the clotting of the carbon and the gas leaking never ends.

Gas leakage is ok though.

For instance if you have an AR with a fixed gas block that is properly gassed and install an adjustable gas block, it's quite likely that the gun will have cycling issues unless you open the gas port or go with a lighter buffer. Many people are not aware of this.

That's a relief. Thanks, Chad. Any 308 buffer recommendations for a rifle length gas system and rifle length buffer tube (if it matters)?

inkd said:
Were you having cycling issues with it from the beginning and changed to an SLR gas block?

Yes, but that was because the original gas block was aluminum (I know, I know) and would leak gas and move a bit from heat expansion. I drilled and pinned the SLR, so that is no longer a concern.

John from MD said:
My question also. Are you planning to run a can?

Not in the near future. I got the adjustable gas block so it wouldn't be over gassed. I planned on opening it just enough to cycle reliably.

clandestine · Dec 18, 2017

Just use a standard weight .308 rifle length buffer.

You need to check carrier travel. What can happen is the fat portion of the carrier will slam into the lower under it's cycle and cause damage.

To check, remove the upper from the lower, remove the BCG, and insert the BCG into the buffer tube. The buffer should stop the carrier from traveling too far back and allowing the fat portion from making contact with the lower where the buffer tube screws in.

inkd · Dec 18, 2017

TheRussianNightmare said:
Yes, but that was because the original gas block was aluminum (I know, I know) and would leak gas and move a bit from heat expansion.

If you had to open the adjustment screw up as far as you are saying, I wonder if it's lined up properly? I have SLR's on all my rifles and don't have them opened as far as it sounds like yours is?

Is it cycling properly now?

inkd · Dec 18, 2017

clandestine said:
Just use a standard weight .308 rifle length buffer.

You need to check carrier travel. What can happen is the fat portion of the carrier will slam into the lower under it's cycle and cause damage.

To check, remove the upper from the lower, remove the BCG, and insert the BCG into the buffer tube. The buffer should stop the carrier from traveling too far back and allowing the fat portion from making contact with the lower where the buffer tube screws in.

Would that cause cycling issues or just damage to the lower? I will be function checking a .308 tomorrow and if there are issues, I'd like to be able to check them out on the spot.

clandestine · Dec 18, 2017

inkd said:
Would that cause cycling issues or just damage to the lower? I will be function checking a .308 tomorrow and if there are issues, I'd like to be able to check them out on the spot.

It can do both. It's VERY common on .308 AR's.

inkd · Dec 18, 2017

clandestine said:
It can do both. It's VERY common on .308 AR's.

Okay, I'll keep an eye out for it tomorrow. I ran a few rounds through it when I completed it and it functioned fine. But, it was only a few rounds.

This is another barrel like the .300Blk I sent to you. I finished it in the summer class in North Carolina and opened the gas port in increments. I am hoping it doesn't have an issue with the suppressor attached :sad20:

clandestine · Dec 18, 2017

inkd said:
Okay, I'll keep an eye out for it tomorrow. I ran a few rounds through it when I completed it and it functioned fine. But, it was only a few rounds.

This is another barrel like the .300Blk I sent to you. I finished it in the summer class in North Carolina and opened the gas port in increments. I am hoping it doesn't have an issue with the suppressor attached

If it cycles without the can you should be fine if you attach the can and have an SLR. If you don't have an SLR you may have issues with overgassing or extraction.

inkd · Dec 18, 2017

clandestine said:
If it cycles without the can you should be fine if you attach the can and have an SLR. If you don't have an SLR you may have issues with overgassing or extraction.

No SLR on this one. I'll find out tomorrow if there are issues.

clandestine · Dec 18, 2017

inkd said:
No SLR on this one. I'll find out tomorrow if there are issues.

If it won't cycle with the can it's overgassed and will need to be taked with some buffer/spring or an adjustable gas block.

Adding a can can suck for a big bore like a .308 AR. The SLR is almost a necessity if you suppress them.

Powder Residue on SLR Gas Block?

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