300 Blackout Testing

[n2omike]

Took four different loads to the range for some testing. Took the chronograph for some velocity and accuracy testing. Platform is a Palmetto State Armory AR15 in 300 BO with a 10.5" barrel with 1 in 7 twist, muffler and 5X Bushnell scope.

I also took a 12 gauge shotgun to the range out of curiosity to velocity test some slugs. This turned out to be a mistake, as I shot the chrono with the very first shot. Oh well... $80 down the drain! ...and no velocity testing today! lol

Anyway, I had enough rounds loaded that I could still do some accuracy testing. Berrys 220 grain plated bullets were used for all trials. The powders were 10.5 grains of VV120, 10.5 grains of 4227, 9.0 grains of 2400 and 8.6 grains of Lil Gun. All cycled the gun just fine, and I've tested even lower does of these powders with success. Gun has a pistol length gas system.

At 33 yards both the VV120 and 4227 did great! The VV120 was amazing, and put all the bullets through the same hole! The 4227 wasn't far behind. The 2400 came after that and the Lil Gun was the worst.

At 50 yards, the VV120 started to spread out! ....but the 4227 stayed tight. I shot two groups at 50 yards with the VV120 to make sure it wasn't just me. These are the center and top right targets.

I WISH I WOULD NOT HAVE SHOT THE CHRONO!!! LOL
My theory is that the VV120 loads may be a little slow, and are destabilizing out past 33 yards. I'll need to order another chrono, make some hotter loads and test. It also seemed to be the quietest by a small margin. We'll see, but the VV120 seems to have a lot of promise! ...as does the 4227.

Thoughts? Experiences?

 

[gudaki]

Looks like you're off to a great start.

 

[Soonerpesek]

NICE.....

Kinda interesting how the VV load went from vertical to horizontal stringing, and the 4227 load went from horizontal to vertical stringing with the distance change......

 

[n2omike]

NICE.....

Kinda interesting how the VV load went from vertical to horizontal stringing, and the 4227 load went from horizontal to vertical stringing with the distance change......

Some of that could also be me... as it's only a 5X scope at 50 yards.
The main things I'm seeing, are that the VV120 and 4227 seem to have the most promise. I NEED the chrono to see if it is velocity related. From previous velocity testing, my initial assumptions are that the Berrys bullets need to be near the top end of subsonic to shoot their best out of my 1 in 7 twist gun.

Oh, just ordered another Caldwell chronograph. I bought the current (broken) chrono this past February for $74 through Amazon. I just ordered another one, and they were $99 but not in stock. Will ship when they get them. Cost more than that on Ebay. THANKS BRANDON. LOL

 

[n2omike]

I was looking at the targets a little more closely... particularly the VV120 at 50 yards and noticed the 'flyer' on the top right target was definitely destabilized. It's easy to see that it went into the target crooked. I saw a video on Youtube (one of the big guys... Ultimate Reloader (Gavintoobe) maybe) who had a hard time stabilizing the 300 BO Berrys bullet. I believe this bullet needs just a little more speed than what the VV120 was giving it to fly true. I'll add around 0.5 grains and see what it does. If it cracks the sound barrier, I'll shoot for the middle. I had previously velocity tested the 4227 loads, and they were between 1050 and 1100 fps. Those worked fine. Anyone else play with the Berrys 220 grain 300 BO bullets?

 

[AJC1]

Seems as there a lot of good powders for 300bo but 1680 seems a favorite. Mag pistol through fast rifle seems to work... I have a lot of 4198 and 2400 so I would test those...

 

[n2omike]

Seems as there a lot of good powders for 300bo but 1680 seems a favorite. Mag pistol through fast rifle seems to work... I have a lot of 4198 and 2400 so I would test those...

1680 is popular... especially with rifle length gas systems that need a lot of gas to operate. However, with subsonic loudness becomes important. Slow and gassy powders make more noise. The difference can be significant. I don't have 1680 but did try H110/W296. It was significantly louder than 4227. I'm assuming 1680 might be the same.

The pistol length gas systems are a LOT more forgiving when it comes to powder choice. A gun can run much faster, less gassy powders and still run just fine... especially with a muffler in place.

2400 works okay in my gun. Haven't tried 4198.

 

[Lennyjoe]

I use 1680 exclusively in my 10” barreled, AAC Cyclone suppressed .300 BO AR. Had no problems building a load with 190 Sub-X and 208 gr BTHP subs.

 

[n2omike]

Well, the new chrono came in, and I finally got a chance to go back to the range to velocity test the above loads.
As was suspected, the VV120 loads were a bit light. Need to bump those up a bit and try again.
Some of the others left me scratching my head!
I shot 5 rounds of 2400, 4227, etc.
The order goes across the top... 2400, 4227, 10.5 grain VV120, 10.0 grain VV120, Lil Gun, 4227 AGAIN, 2400 AGAIN and 10.0 grain VV120 AGAIN.

What's weird, is that both the 2400 and 4227 showed significantly slower velocities the second round! The gun was definitely getting warmer, but is that a thing? Any idea what caused that? The groups opened up a bit when they slowed down as well.

I loaded another lot of 3.8 grain HP38 147 gr RMR FMJ and tested 10 rounds. This was all mixed range brass. I purposely tried to choose a wide mix of plain, shiny, nickel and dingy brass of mixed brands... and they still came out incredibly consistent. Around 10 fps or so faster than the last lot, but I had to reset the powder measure, as it was used for the 300BO rounds. Off a rest, it was no big problem to hit a 12" square plate at 100 yards using a green dot sight on the 5" barrel Canik METE.

Not sure if a 10.0 grain VV120 got mixed in with the 10.5... highly possible. Those are the only two rounds I had left labeled 10.5 grain VV120. The rest were 10.0. Accuracy wise, these bullets don't like to go too slow. Thinking about bumping the VV120 up to around 10.8 grains and trying again?

The wife was kind enough to come to the range and be my secretary. lol

Thanks

 

[n2omike]

Loaded up some more 300BO and also tested the 9mm in the 10.5" carbine.
Before, the 10.5 grain load of VV N120 seemed a little light, and the 10.5 grain load of 4227 had some mixed results.
Shot 10 rounds of N120, 10 rounds of 4227, 10 rounds of N120 and 10 more rounds of 4227.
All 300 BO used CCI SRM primers
Berrys 220 grain plated .308" bullets

Temp was around 80 degrees. None of the rounds went supersonic. Both N120 and 4227 had very similar accuracy. N120 load seems about where it needs to be. May reduce the 4227 load to 10.4 grains.

Previous testing was with transformed Lake City 5.56 brass. These were loaded in Starline cases. I did NOT resize the cases. All I did was deburr the case mouths.

All shots were done at one sitting. I find it interesting that 300 BO velocities seem like they decrease slightly between sets as the gun warms up.

VV N120 10.8 gr
1076
1087
1101
1094
1057
1099
1089
1089
1095
1082

4227 10.5 gr
1147
1137
1119
1126
1119
1109
1125
1103
1114
1110

VVN120 10.8 gr
1070
1062
1034
1061
1037
1042
1058
1022
1045
1046

4227 10.5 gr
1117
1100
1089
1090
1095
1088
1075
1073
1102
1091

9mm 3.8 gr HP38 w/RMR 147 gr FMJ in a 10.5" AR. Mixed brass. 1.14" OAL CCI SPP
REALLY liking this load! Also accurate.
1085
1098
1105
1102
1102
1088
1093
1098
1110
1109