300Blackout Journey Page 3

May 18, 2014 Update

Having discovered a reliable supersonic load that will be my favorite/go to load, I decided to start work on developing a subsonic round. As my results will show this is much more difficult. I would end up purchasing lead 245gr 300Blackout Thumpers from Missouri Bullet Company.

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Today Darrell and I had great results with the Remington Micro 7 with Yankee Hill Suppressor and 11.3gr of Accurate 1680 and 220gr Sierra Match Kings which shot under 1 inch at 50 Yards and quieter then Remington Factory 220gr Subsonics. What I had really hoped for were for some of my test Missouri Bullet Company bullets and load would work, this would prove to be frustrating, yet still alot of fun.

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On this day we would not have much luck getting this round to function 100% in our AR’s. I think the loads were a little long for the PMAGS at a COAL of 2.139,

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though we did find that with a new GI mag with Orange follower Darrell recently purchased for bench shooting worked much better.

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I think this hunk of lead is going to be utilized only in the bolt action and could be a good reason for me to get a Remington 700 chambered for 300 Blackout :). Sounds like a good reason to get a bolt action to me.

Today I would also have some test loads of my favorite plinker supersonic rounds. I have previously tested these rounds and knew what it was capable of. What I would be testing is an RCBS Chargemaster against my 20 Year old RCBS Uniflow. My RCBS Chargemaster throws would also be weighed on a RCBS 5.0.5 Beam scale the same used for the uniflow. Since these loads are loaded with H110 which meters great I really didn’t expect to find much difference. What I really wanted the Chargemaster for was throwing stick powder which will be tested on another day.

 

Rifle Barrel Length Gas Tube Length Ammunition – Powder-Manual COAL Bullet Weight/Bullet Type Velocity FPS Average Velocity FPS ES SD Group Size Weather Conditions Bolt Lock Back
Rock River Lower Wilson Barrel 300BlackOut 16′ 1/8 Twist Carbine Reload H110-15.5gr Uniflow 2.100 150gr Hornady FMJ 1862 1861 44 15 Testing to see which measure gives me lower ES and SD 63 Degrees Y
Low 1836
Hi 1880
1864
1864
Rock River Lower Wilson Barrel 300BlackOut 16′ 1/8 Twist Carbine Reload H110-15.5gr RCBS Chargemaster 2.100 150gr Hornady FMJ 1880 1881 13 5 Testing to see which measure gives me lower ES and SD 63 Degrees Y
1885
Hi 1888
Low 1875
1880

Continued on page 4

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