Subsonic Build Questions

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jbrinkerhuff
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Subsonic Build Questions

Post by jbrinkerhuff » Mon Oct 07, 2013 2:59 am

Bullets => Missouri Bullet Company 245 Grain RNFP (will they work in CMMG barrels? Their website says chambers are cut up to 220 Grain)

Barrel => CMMG 16" with cabine gas port location (any issues with gas piston at the carbine location? Guy at the gun show says to only use the pistol location gas port) (any issues with 5/8-24 with Yankee Hill QD suppressor mount?)

Suppressor => Yankee Hill Machine Titanium 308 QD

Gas Piston System => CMMG (does it support gas metering for a suppressor like my Adams Arms Piston Kit?)

Load => 10.5gr. of A1680 / COAL of 2.155" (anyone use this load that I found for Missouri Bullet?)

I would like to be able to create subsonic rounds that cycle the bolt with the suppressor in place. I apologize in advance if these topics have been discussed in other threads.

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KingIX
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Re: Subsonic Build Questions

Post by KingIX » Mon Oct 07, 2013 4:15 am

Alot to cover.. suppressor and muzzle device are ok

Not sure about 245gr bullets seems most guys stop around 220
with the ar...

I have alway ran little gun powder for my subs so not much help there

Pistol gas is the way to go on the 300.... can carbine work yes
may take some adjusting to set up and isnt the best imo if u plan on shooting subs and supers

Piston? ?? Why DI works fine and the round like di...if i remember right a piston
system would take some adjusting to get right if you can get it right at all

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gds
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Re: Subsonic Build Questions

Post by gds » Mon Oct 07, 2013 8:24 am

the Missouri cast bullet is as I understand it the same as the NOE 247gr that I cast. I have had good results feeding in an AR15, both a 16 inch 1 in 10 twist and a 9.5 inch 1 in 8.5 twist, both subsonic. I have used it also in my AAC model 7. accuracy has been around 1.5 inch at 50 yds. Occasionally i get good sub half inch 50 yd 3 shot groups. My best consistent accuracy, meaning constant 3 shot groups less than 1/2 in subsonic at 5o0 yds is out of my savage .308 winchester with 1 in 10 twist.

A carbine gas system with a 16 inch barrel will work. Some have had issues doin subs, but that usually is dependent on gas port size. Not in all cases, but it can. My 16 inch is a custom job with a .125 gas port. Have been told that this could cause over gassing issues with supersonic loads. Have not had an issue with this so far and have been shooting it for almost 4 years.

Can not answer as far as gas piston. My understanding has been the a gas piston 300 blk for subs, is a problem, however I know companies have been working on it, so maybe my info is dated..

your load of 1680 is very close to my load with 1680 and this bullet. I believe i was using 11 gr, and my COL was 2.135. but I ran out of 1680 last year and have not played with it in a while.
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talonxracer
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Re: Subsonic Build Questions

Post by talonxracer » Mon Oct 07, 2013 9:21 am

A1680 is a far better choice than Lil'Gun for subs and I have also had success with H4198(newer extreme powder or old SC)
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KingIX
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Re: Subsonic Build Questions

Post by KingIX » Mon Oct 07, 2013 12:40 pm

talonxracer wrote:A1680 is a far better choice than Lil'Gun for subs and I have also had success with H4198(newer extreme powder or old SC)
I agree.. little gun is alot easier for me to find locally
thats the only reason..

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