SO, which is it?

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modernhistorian
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Re: SO, which is it?

Post by modernhistorian »

I bought one of these, and put it on my pre-ban A2-style lower. I tried it yesterday, with factory and hand loads. The factory Remington 300 AAC blackout with 220 gr. bullet clocked average 947 fps with a standard deviation of 37. My loads, using Hornady 208 gr. Amax atop 10.5 or 11 gr. of RL-7, showed 934 and 998 averages, with SD of 39 and 59. Both factory and hand loads would extract, but not feed the next round or lock back.

I am surprised at the large SD, especially on my loads, which I trickle charge. For comparison, my R700 in .308 ran an SD of just 7 fps that day, with a much higher velocity (2571 fps). Are these kind of variations in velocity considered normal in subsonic 300 BLK?

Of course, I want it to feed rounds. A suppressor should fix that, is my understanding, but that will take a while. (Haven't picked one yet, either, though I lean toward the SAS arbiter. I would like to mount the same suppressor on the 300 and the .308.) In the meantime, would a different buffer spring help?
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JohnInNH
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Re: SO, which is it?

Post by JohnInNH »

modernhistorian wrote:I bought one of these, and put it on my pre-ban A2-style lower. I tried it yesterday, with factory and hand loads. The factory Remington 300 AAC blackout with 220 gr. bullet clocked average 947 fps with a standard deviation of 37. My loads, using Hornady 208 gr. Amax atop 10.5 or 11 gr. of RL-7, showed 934 and 998 averages, with SD of 39 and 59. Both factory and hand loads would extract, but not feed the next round or lock back.

I am surprised at the large SD, especially on my loads, which I trickle charge. For comparison, my R700 in .308 ran an SD of just 7 fps that day, with a much higher velocity (2571 fps). Are these kind of variations in velocity considered normal in subsonic 300 BLK?

Of course, I want it to feed rounds. A suppressor should fix that, is my understanding, but that will take a while. (Haven't picked one yet, either, though I lean toward the SAS arbiter. I would like to mount the same suppressor on the 300 and the .308.) In the meantime, would a different buffer spring help?

A lighter buffer or spring would do it.. but do not shoot supers with that set up. I have found that powders that will provide the correct port pressures to cycle an AR with subs are not the best powders for ES and SD. I just stumbled on American Select. 5.5 gr under a 210 lead and got good SD and ES. it has 2x the volume of the W231 load I use .. so it is volumetric friendly. I did not weigh each load.
ES 30 SD 11 1000 fps with just using a measure. not bad.

A1680 is all over.
Long distance, the next best thing to being there!
modernhistorian
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Re: SO, which is it?

Post by modernhistorian »

The SAS distributor is here in Colorado, and I've just purchased one of the titanium Arbiters. I'll start paperwork tomorrow. In the meantime, I'll try upping the load to 11.5 and 12 grains; rather not change spring unless I have to. Suppressor should fix this problem by increasing back pressure, no?

The gun is fun to shoot, and accuracy is not bad.
jwb47
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Re: SO, which is it?

Post by jwb47 »

I have a smith and the only ammo I have run through it so far is remington factory 220 grain subs. so far it has cycled just fine with groups around 1.5 inch at 100 yds.

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modernhistorian
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Re: SO, which is it?

Post by modernhistorian »

I put a Magpul stock and sprayed the spring with silicon. The FTF rate is down to 1 in 10 now, but I think it will do much better when I get my titanium Arbiter. I put an Eotech sight on top, and will post an accuracy report later. On an unrelated note, I have begun stockpiling bullets. If Obama is re-elected as the SIC, I think that EPA may at last ban lead ammo.
Omega-Man
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Re: SO, which is it?

Post by Omega-Man »

[quote="modernhistorian"]I bought one of these, and put it on my pre-ban A2-style lower. I tried it yesterday, with factory and hand loads. The factory Remington 300 AAC blackout with 220 gr. bullet clocked average 947 fps with a standard deviation of 37. My loads, using Hornady 208 gr. Amax atop 10.5 or 11 gr. of RL-7, showed 934 and 998 averages, with SD of 39 and 59. Both factory and hand loads would extract, but not feed the next round or lock back. quote]

Are you happy with the purchase after getting some time in with it ? :?:
modernhistorian
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Re: SO, which is it?

Post by modernhistorian »

Just now, I am shooting supersonic, using H110 and SMK 125 gr. Those function perfectly. I may wait until I get my suppressor before trying subsonic again.
mdyer
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Re: SO, which is it?

Post by mdyer »

Just bought a smith complete rifle in blackout. Shot it at 50 yds wih rem 220 and a vortex strikefire red dot. It shot .75 easily. So I'd say with a regular scope it would do close moa at 100. That dot covers a lot of the bullseye. It cycled fine everytime. Actually threw the brass about 6-8 feet. I love it.
Soy
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Re: SO, which is it?

Post by Soy »

Its My understanding that Blackout will shoot whisper but that whisper won't shoot black out. I've seen S&W M&P Whisper/Blackout advertised. This would lead me to believe that its a Whisper that there saying will fire Blackout, which is in conflict with everything I've read. Any One? Any One? Any Info would be nice.

Soy
20X11
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Re: SO, which is it?

Post by 20X11 »

Holy thread resurrection Batman!!! Dug that up from 2 years ago?
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