waffentomas
03-13-15, 15:29
Hey all!
Just completed my first build and got back from the woods a while ago. Thought I'd post the load results for those interested.
Elevation was about 1000 feet in the Cascade range. Temp was about 60, and sunny.
The build I completed is a 300 Blackout with a 12" barrel, 1/8 twist, pistol length gas system. PSA upper with a Colt BCG.
I've been hand loading over 20 years, but this is my first 300 BO build. All shots went through the chronograph from 15'
Load #1 was a Hornady 150gr FMJ-BT. I use these for a lot of my .308 projects for obvious reasons. Plus, I have a lot of them as I have to feed the .308 Galil and M1A. Seated to 2.130", over 19 gr of AA5744. This OAL is seats the bullet with the cannelure fully exposed. CCI #41 primer, once fired LC brass in all loads today.
String went as follows:
1836, 1792, 1846, 1861, 1850, 1852, 1870, 1882, 1895, 1836, 1836, 1829. AVG: 1849 fps. SD: 26.91. ES: 103. E: 1139 ft. lbs.
As expected this load deposited the brass in a different location than the other 3 loads. This load went through 1/2" solid aluminum like hot butter, but barely dented 3/4" tool steel.
Load #2 was a subsonic load. I was curious about this one as I have read about subsonic loads struggling to function some of these rifles. But I had no malfunctions at all today with any load, and I put 400 rounds total through it. This one was a Nosler 220gr Partition, over 11.0 gr of AA5744, OAL 2.230". I was concerned with this load feeding properly, as its nose is rounded with lead exposed, but...no issues.
String went as follows:
995, 962, 949, 973, 963, 951, 935, 975, 973, 973. AVG: 965 fps. SD 16.86. ES: 60. E 455 ft. lbs.
This load put a small dent in the 1/2" aluminum. It was interesting firing the light fast load first, then the slow heavy load next. The recoil impulse was noticeably different.
Load #3 was a Hornady 208 gr AMAX over 11.0gr of AA5744. Seated to OAL 2.230" I was curious how this load would perform vis-a-vis the 220gr above, as the only difference is the bullet.
String went as follows:
1096, 1116, 1098, 1115, 1130, 1086, 1063, 1116, 1060, 1110. AVG: 1098 fps. SD: 23.05. ES: 70. E: 557 ft. lbs.
Same result as above on the aluminum. As I was trying to get a load as close to super-sonic, without surpassing it, as possible. This load appears to be the initial one to work with, when the stamp comes through... I do think I can get some more velocity from the 220, however. Just shy of the sea level 'mach 1' speed of 1116 fps, this load did better than I thought it would. I should probably pull the load back .3gr or so, to keep all shots under 1100 fps.
Final load was a 180gr Nosler solid base. This bullet is not made any more, but is a BT, with exposed lead spitzer tip. I was concerned that the load data, all using a 16" barrel on Accurate's web site, would suffer some lost fps in my shorter barrel. I was surprised the 220 and 208 did as well as they did, as I figured they'd both be at least 50 fps slower than they actually were in the shorter 12" barrel. Wanting near near speed of sound, I upped the powder on this load, but it turns out I didn't need to, 10.5gr would have been fine. Actual load was 13.0 gr AA5744, 2.140" OAL.
String went as follows:
1317, 1232, 1248, 1260, 1230, 1244, 1283, 1262, 1327, 1272. AVG: 1267.5 fps. SD: 33.2. ES: 107. E: 642.3 ft. lbs.
A little bigger dent in the aluminum than the previous two, and did nothing to the steel. As you can see, she was well above super-sonic.
Hope you find the data interesting and that it helps out somebody.
Tom
Just completed my first build and got back from the woods a while ago. Thought I'd post the load results for those interested.
Elevation was about 1000 feet in the Cascade range. Temp was about 60, and sunny.
The build I completed is a 300 Blackout with a 12" barrel, 1/8 twist, pistol length gas system. PSA upper with a Colt BCG.
I've been hand loading over 20 years, but this is my first 300 BO build. All shots went through the chronograph from 15'
Load #1 was a Hornady 150gr FMJ-BT. I use these for a lot of my .308 projects for obvious reasons. Plus, I have a lot of them as I have to feed the .308 Galil and M1A. Seated to 2.130", over 19 gr of AA5744. This OAL is seats the bullet with the cannelure fully exposed. CCI #41 primer, once fired LC brass in all loads today.
String went as follows:
1836, 1792, 1846, 1861, 1850, 1852, 1870, 1882, 1895, 1836, 1836, 1829. AVG: 1849 fps. SD: 26.91. ES: 103. E: 1139 ft. lbs.
As expected this load deposited the brass in a different location than the other 3 loads. This load went through 1/2" solid aluminum like hot butter, but barely dented 3/4" tool steel.
Load #2 was a subsonic load. I was curious about this one as I have read about subsonic loads struggling to function some of these rifles. But I had no malfunctions at all today with any load, and I put 400 rounds total through it. This one was a Nosler 220gr Partition, over 11.0 gr of AA5744, OAL 2.230". I was concerned with this load feeding properly, as its nose is rounded with lead exposed, but...no issues.
String went as follows:
995, 962, 949, 973, 963, 951, 935, 975, 973, 973. AVG: 965 fps. SD 16.86. ES: 60. E 455 ft. lbs.
This load put a small dent in the 1/2" aluminum. It was interesting firing the light fast load first, then the slow heavy load next. The recoil impulse was noticeably different.
Load #3 was a Hornady 208 gr AMAX over 11.0gr of AA5744. Seated to OAL 2.230" I was curious how this load would perform vis-a-vis the 220gr above, as the only difference is the bullet.
String went as follows:
1096, 1116, 1098, 1115, 1130, 1086, 1063, 1116, 1060, 1110. AVG: 1098 fps. SD: 23.05. ES: 70. E: 557 ft. lbs.
Same result as above on the aluminum. As I was trying to get a load as close to super-sonic, without surpassing it, as possible. This load appears to be the initial one to work with, when the stamp comes through... I do think I can get some more velocity from the 220, however. Just shy of the sea level 'mach 1' speed of 1116 fps, this load did better than I thought it would. I should probably pull the load back .3gr or so, to keep all shots under 1100 fps.
Final load was a 180gr Nosler solid base. This bullet is not made any more, but is a BT, with exposed lead spitzer tip. I was concerned that the load data, all using a 16" barrel on Accurate's web site, would suffer some lost fps in my shorter barrel. I was surprised the 220 and 208 did as well as they did, as I figured they'd both be at least 50 fps slower than they actually were in the shorter 12" barrel. Wanting near near speed of sound, I upped the powder on this load, but it turns out I didn't need to, 10.5gr would have been fine. Actual load was 13.0 gr AA5744, 2.140" OAL.
String went as follows:
1317, 1232, 1248, 1260, 1230, 1244, 1283, 1262, 1327, 1272. AVG: 1267.5 fps. SD: 33.2. ES: 107. E: 642.3 ft. lbs.
A little bigger dent in the aluminum than the previous two, and did nothing to the steel. As you can see, she was well above super-sonic.
Hope you find the data interesting and that it helps out somebody.
Tom