300Blackout Journey Page 2

Utilizing Midwayusa, Brownells and a few local shops I manage to get everything I needed to completely build my first AR. At some point I may get around to submitting the government form 1 , pay my fees and purchase a SBR (short barrel) to go with this rifle. Until then the major parts I used are

  • CMMG 1/7 Twist, Pistol length gas system, 16′ carbine barrel. I read of to many issues with other length systems and decided on pistol length.
  • Standard GI Trigger
  • Sun Devil Lower
  • Yankee Hill
  • DPMS Upper
  • Mako GLR16 Butt Stock
  • Burris AR-P.E.R.R. 1 Piece Extended Scope Mount
  • Wilson Combat Accu-Tac Flash Hider
  • Double Star Lower Parts Kit
  • Double Star Low Profile Gas Block
  • Weaver 3-12×44 Scope — Lit Reticle and Scope caps.

These are the major components I have assembled along with a few other minor parts which can be seen in the pictures below.


Now that I have completed my build it was time for me to test it on the range. I loaded up subsonic ammunition first and was going to use existing Troy Battle Mags and PMAG Mags 20 and 30 rounds. During my research you will find many who insist on a special overall length for every load for the 300Blk to function properly. That is loading so the projectile is seated in the case so that the round fits in the magazine .250 from the ogive of the projectile away from the tab inside the magazines. I myself for the most part stuck with the overall length’s in the publications and found them to almost be spot on to this suggestion. Following this guidance my Rifle has been very reliable with many different loads.


Now that all rifles and loads are functioning correctly this is where I began to get serious about load development. I would work up loads record them in my spreadsheet, fire them across the chronograph and then test the same load for accuracy from the Caldwell Pro Bench Rest.

All accuracy test was done at 50yards outdoor with the Chronograph 7 yards away from the muzzle of each rifle.



April 6, 2014 Update?

Lately I have been wanting to come up with a good economical plinking load for the 150gr Hornady Bullets I have. The intent was to use a powder that I seem to always have access to through my good friend Jeff of JRS reloading along with the Hornady 150gr FMJ. I used the loading data out of the Hornady #9 reloading manual.

LilGun 16.4,?COAL 2.062,?Hornady 150gr FMJ.

The Hornady manual calls for a COAL of 2.220 this is the reason I have the COAL highlighted in red. At this length Hornady says the max load is 17gr. But I was uncomfortable with this load as the COAL had the 150gr bullet with very little bullet seated in the case. I decided to seat the bullet to its cannelure and reduce the max load. The deeper you seat the bullet the more overall and peak pressure is going to increase. Of course I worked up loads starting at 15.6.

What I really found interesting about this load is the fact that it seemed to have more noticeable recoil then other loads I have tested, but was definitely less indicated pressure upon examining the cases.

The Chronograph was 5 Yards away from the firing line.

Center 9 Shots measure 1.315 excluding the pulled shot caused by me. Accuracy was tested at 50 Yards. Happy with this load I decided to try and zero in my iron sites also. Those are the 5 shot groups on the upper and lower left targets.

For the first time also I came across brass that was to thick to use, no matter what it would not fit in my Sheridan. I also separated my upper away from the lower and drop the round in the chamber and neither would allow the bolt to close all the way. IVI marked brass should be added to the list of not usable for 300Blackout.

Sheridan gauge saves me again.

May 3, 2014 Update Great Day On The Range

In the previous update I mentioned I was looking for a supersonic load using my 150gr Hornady bullets which I have an abundance of. Though the previous load was a nice shooter I found one a little better. I was extremely please having shot these at 100 Yards.

H110 15.5gr COAL 2.100,?Hornady 150gr FMJ.

The Chronograph was 5 Yards away from the firing line.



Continued on 300Blackout Journey Page3