n2omike
Member
- Joined
- Feb 19, 2021
- Messages
- 469
Decided to try the 300 Blackout, so I got a 10.5" PSA 300 BO upper to try on my 5.56 AR 15.
I tested with Winchester 296 (H110) and Berry's 220 Copper Plated bullets.
I loaded up 9.5, 10.0, 10.5, 11.0, 11.5 and 12.0 grain loads all at 2.150" overall length and took the chrono with me to find a good subsonic powder charge.
First trip to the range, about 10 seconds after turning the chrono on, the display said 'BAT', which means 'dead battery'. Great. lol I went ahead and shot few each of 9.5 to 10.5 and didn't hear any sonic booms... then went home to get a new battery.
The lower powder charges were very inconsistent. Total range of velocity was close to 100 fps. At 10.5 grains it ranged from around 1040 to 1150, with one going supersonic. The higher the charge weight, the more consistent things got, and up at 12.0 grains, it was within around 20 fps.
Here's the kicker... You may have noticed that I didn't mention primers yet... as that is a little embarrassing. lol I have a lot going on this weekend, and in my quest to get this stuff tested before evening, I grabbed CCI Small PISTOL primers by mistake. At these light loads, they showed no signs of pressure, so I didn't catch it at first. My main question... Are small rifle primers hotter than pistol primers? Would using small rifle primers help make the lower charges more consistent?
The gun shot great. Not a single misfire or failure to cycle in any of the 80 rounds fired, and at 33 yards, most of the bullet holes at the higher charge weights were touching each other. Zero issues with the Berry's Bullets at the 1 in 8 rifling of the PSA barrel. All I did was stick on my existing lower.
Below is the upper:
https://palmettostatearmory.com/psa...eight-m-lok-upper-with-bcg-ch-5165448418.html
Thanks!
I tested with Winchester 296 (H110) and Berry's 220 Copper Plated bullets.
I loaded up 9.5, 10.0, 10.5, 11.0, 11.5 and 12.0 grain loads all at 2.150" overall length and took the chrono with me to find a good subsonic powder charge.
First trip to the range, about 10 seconds after turning the chrono on, the display said 'BAT', which means 'dead battery'. Great. lol I went ahead and shot few each of 9.5 to 10.5 and didn't hear any sonic booms... then went home to get a new battery.
The lower powder charges were very inconsistent. Total range of velocity was close to 100 fps. At 10.5 grains it ranged from around 1040 to 1150, with one going supersonic. The higher the charge weight, the more consistent things got, and up at 12.0 grains, it was within around 20 fps.
Here's the kicker... You may have noticed that I didn't mention primers yet... as that is a little embarrassing. lol I have a lot going on this weekend, and in my quest to get this stuff tested before evening, I grabbed CCI Small PISTOL primers by mistake. At these light loads, they showed no signs of pressure, so I didn't catch it at first. My main question... Are small rifle primers hotter than pistol primers? Would using small rifle primers help make the lower charges more consistent?
The gun shot great. Not a single misfire or failure to cycle in any of the 80 rounds fired, and at 33 yards, most of the bullet holes at the higher charge weights were touching each other. Zero issues with the Berry's Bullets at the 1 in 8 rifling of the PSA barrel. All I did was stick on my existing lower.
Below is the upper:
https://palmettostatearmory.com/psa...eight-m-lok-upper-with-bcg-ch-5165448418.html
Thanks!
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