First time out with 300blk and suppresor. Edit- Appears fixed

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[ARCHIVED THREAD] - First time out with 300blk and suppresor. Edit- Appears fixed

Posted: 2/6/2020 6:28:26 PM EDT

I'm guessing it's under gassed but not sure. Bolt also wouldn't lock back 100% of the time. Open to ideas

PSA 8.5 barrel
Silencer co specwar762
Gas block and tube were carry over parts from my 7.5 inch 556 pistol
Unsure of what I have for buffer and spring. Ran 556 just fine

Attached File

Posted: 2/6/2020 7:30:02 PM EDT

[#1]

What buffer weight and gas port size?
In my 300 blk I'm using a carbine buffer weight with 9" barrel and the gas port is .098"

Posted: 2/6/2020 8:09:31 PM EDT

[#2]

Barrel sku is 7782517

Couldn't find a port size listed. Guns not coming apart tonight.

Buffer I believe is from a PSA kit. Always used the same buffer between an 18inch and a 7.5 inch in 556. And now this 8.5 300blk.

Spring might be a extra power wolf spring.

Check out the brass Mark's and the charging handle pulled full rear.

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Also was using a magpul 300 blk 30 round mag

Posted: 2/6/2020 8:15:04 PM EDT

[#3]

Bolt carrier and gas tube

Attached File

Buffer by its self

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Posted: 2/6/2020 8:43:07 PM EDT

[#4]

Did you try shooting with and without the suppressor? Where is your brass landing?

Everybody always assumes undergassed first. Does it shoot impressively soft? I have a 10.5" PSA barrel and it had a huge gas port. You could be overgassed and the bcg overrunning the magazine.

I like to use another known good rifle and swap parts around. Start with swapping lowers. Doesn't fix the problem and the issue is likely in the upper. Swap BCG next. So on and so forth.

Posted: 2/6/2020 8:48:54 PM EDT

[#5]

Ditch the extra power spring. You shouldn't be undergassed with a suppressor on the gun, unless your gas block is misaligned. Suppressors generate significant back pressure. I'm guessing your gun won't cycle any better with the suppressor off. What kind of gas to the face experience do you get with each round? With my gun, I can taste the powder, even with a gas buster charging handle.
I've got a DD SBR 10.3 in 300 blackout. With a suppressor on it, it cycles weak ass subs that won't run in a gun sans suppressor.
If you suppressor is a quick detach, always double check that you have mated it up correctly. The 3rd time I took mine out, it sailed down range with the second round, luckily I didn't have a baffle strike.

Posted: 2/6/2020 8:54:27 PM EDT

[#6]

Quote History

Quoted:
Did you try shooting with and without the suppressor? Where is your brass landing?

Everybody always assumes undergassed first. Does it shoot impressively soft? I have a 10.5" PSA barrel and it had a huge gas port. You could be overgassed and the bcg overrunning the magazine.

I like to use another known good rifle and swap parts around. Start with swapping lowers. Doesn't fix the problem and the issue is likely in the upper. Swap BCG next. So on and so forth.

View Quote

I have a pistol lower I can try. My upper set up is not conducive to taking the suppressor off willy nilly. I have three other rifles to swap parts from. But I think I need to just start by checking the gas port size and the gas block.

I too was curious about over gassed and out running the mag spring.

Posted: 2/6/2020 8:56:42 PM EDT

[#7]

Quote History

Quoted:
Ditch the extra power spring. You shouldn't be undergassed with a suppressor on the gun, unless your gas block is misaligned. Suppressors generate significant back pressure. I'm guessing your gun won't cycle any better with the suppressor off. What kind of gas to the face experience do you get with each round? With my gun, I can taste the powder, even with a gas buster charging handle.
I've got a DD SBR 10.3 in 300 blackout. With a suppressor on it, it cycles weak ass subs that won't run in a gun sans suppressor.
If you suppressor is a quick detach, always double check that you have mated it up correctly. The 3rd time I took mine out, it sailed down range with the second round, luckily I didn't have a baffle strike.

View Quote

Gas to face was not noticeably worse than any of my other rifles. I did notice the mag being full of smoke though.

Posted: 2/6/2020 9:15:21 PM EDT

[#8]

Attached File

I have a drill bit (un marked) that fits perfect but calipers are at work.

Its between a 7/64th bit and a 3/32nd bit (those bits are marked as such)

Attached File

Block could of been mis aligned.

I'll reset the block then mic the bit at work tomarrow.

Edit. Bit was .097. So port must be .098 or so

Posted: 2/6/2020 9:21:13 PM EDT

[#9]

I ran my 10.5” 300 BO with and without my GA Paladin with the same ammo and it worked fine using the standard carbine buffer and spring. My first recommendation would be to use a standard buffer and spring. You generally don’t need to run heavy buffers and springs with .300 BO like you do for short 5.56s.

Posted: 2/6/2020 9:21:27 PM EDT

[#10]

7/64=.109" which sounds about right for a short 300blk.

Posted: 2/6/2020 9:47:46 PM EDT

[#11]

Your gas port size seems fine.
I'd make absolutely sure the gas block is lined up when reassembling.
Get a regular mil-spec spring and weigh your buffer and make sure it's 3 oz.
If that's the case try it out again, and if it still fails I would suggest getting a heavier buffer or individual tungsten weights like these:
https://www.ebay.com/itm/Tungsten-H-H2-or-H3-Weights-1-5-oz-Each-3-Pack-Weights-Total-Weight-4-5-oz/264408245060?hash=item3d8ff5a344:g:uiMAAOSw0h1dOFBD
Then you can start with an H1 work up to H2 if needed.
It seems to me like your bcg might be outrunning your magazine judging from the brass deflector.

Posted: 2/6/2020 10:07:16 PM EDT

[#12]

I bet it’s the extra power spring. Swap it for a Tubb reduced power spring.

It’s basically impossible to overgas a 300 blk running subs to the point of having reliability issues.

Posted: 2/6/2020 10:34:16 PM EDT

[#13]

Quote History

Quoted:
It’s basically impossible to overgas a 300 blk running subs to the point of having reliability issues.

View Quote

I agree with this.

Posted: 2/6/2020 11:28:38 PM EDT

[#14]

Quote History

Quoted:
I bet it’s the extra power spring. Swap it for a Tubb reduced power spring.

It’s basically impossible to overgas a 300 blk running subs to the point of having reliability issues.

View Quote

Posted: 2/7/2020 7:46:08 PM EDT

[#15]

I have this spring. Its shorter and much less strong. Who paints the ends blue?

Also have a stock carbine spring in an un built psa kit I could try

Attached File

Posted: 2/7/2020 10:39:32 PM EDT

[#16]

Quote History

Quoted:
I have this spring. Its shorter and much less strong. Who paints the ends blue?

Also have a stock carbine spring in an un built psa kit I could try
https://www.AR15.Com/media/mediaFiles/308382/20200207_184444_jpg-1267785.JPG

View Quote

Sprinco paints the end of their springs to identify them, but their blue ones (at least the ones I have) arent that dark of a shade of blue.

Posted: 2/8/2020 2:30:27 AM EDT

[#17]

What length gas system do you have? Try using a standard carbine buffer spring. For process of elimination, try using some sonic ammunition and see if it performs different than the subsonic that you are using now.

CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123

Posted: 2/8/2020 11:48:48 AM EDT

[#18]

It's a pistol length gas system. I'm about to head to the range to see if any of these springs I have makes a difference

Edit
Ran 60 rds with no problems. Gonna clean it then next time run 200 rds. See how it does.

Thanks guys

Fixed

Posted: 2/8/2020 1:43:50 PM EDT

[#19]

Heck yeah, glad it's working for you!

[ARCHIVED THREAD] - First time out with 300blk and suppresor. Edit- Appears fixed

AR-15 » Troubleshooting

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