rifledoc
Member
How much H110 are you using for the 110 gr? I am ranging from 19.0 to 19.4 and have a lot of spread. What 110gr you using? I am trying the Hornady V-max and just loaded some Barnes TSX to try.
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Supersonic 300 blackout powders
- Thread starter CoyHunter38
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I'm at 18.5 with 125sst. 19.8 with 101 blackout hammer and I believe 19.5 with the 110 Vmax. All in bolt action and semi auto
rifledoc
Member
Awesome thanks for the info. I loaded up another rounds of 19.0 and 19.4 for the V-max to run and a first ladder of the Barnes, will let you know how they do! I run a 16in R700 bolt. My 7.5 in SBR loves anything but I am only shooting for accuracy to 50 yards because it's my varmint killer when I am in the woods or my truck gun.
QuietTexan
Well-Known Member
You can order one from McGowen, but why? 7 twist in my bolt action runs everything fine. Shooting a 110gn bullet I don't think spin drift is coming into play, it's just normal wind deflection no different than in .224 and .243 barrels.
Maybe your right. I never had a keyhole our anything like that. But my mind just tells my to slow down the twist on the stubbys and speed it up on the longys. Anyway, maybe you are right. But it seems that the 300 hamR slowed down the twist for a pacific reason!
The 300 Hamr wasn't intended to be used for subs like the 300 BLK was.
That's my point!
QuietTexan
Well-Known Member
They're two sides of the same coin. 300 Hamr is a 30-30 that runs in an AR. Velocities are very similar. The Hamr is specifically meant to get .308-level performance out of the smaller AR-15 platform. Similar arbitrary restriction but opposite direction (speed goal) as the 300 BLK was designed to hit (which was subsonic is an AR-15). That's why both use the same parent case, but one case is longer and the other is shorter - based on which bullets they need to push. BLK heavy long slow, Hamr short light fast.
300 BLK has driven the development of short-base .308 bullets like the Barnes TAC-TX 110gn that are designed to not sit past the shoulder junction of the case, maximizing room for powder and increasing velocity past what that little case would otherwise be able to do. Fast twists are required to stabilize the long heavy bullets for subs, but do a surprisingly good job at stabilizing lighter bullets. Especially the light monos that can really get velocity out of the short case.
300 Hamr is meant to do supers only, so it runs a slower barrel twist because there's no need for a slow twist because it's not designed to shoot the heavy long bullets. Square peg-round hole problem if you want to run subs in it though - hit it hard enough and you can make it work, but it's not as easy.
Personally I'm going the 6mm route in the AR (6x45/ aka 6mm - 223) instead of .308 cal for supers, I should meet or beat the 300 Hamr with 95gn bullets in terms of velocity , but I'll be shooting long for caliber bullets with higher BCs (straight weight matching to compare velocities, I know that's not the ideal weight for 300 Hamr). The Hamr will have to use the 130s to catch up to my bullets in desgign, at which point it'll be running slower.
300 BLK has driven the development of short-base .308 bullets like the Barnes TAC-TX 110gn that are designed to not sit past the shoulder junction of the case, maximizing room for powder and increasing velocity past what that little case would otherwise be able to do. Fast twists are required to stabilize the long heavy bullets for subs, but do a surprisingly good job at stabilizing lighter bullets. Especially the light monos that can really get velocity out of the short case.
300 Hamr is meant to do supers only, so it runs a slower barrel twist because there's no need for a slow twist because it's not designed to shoot the heavy long bullets. Square peg-round hole problem if you want to run subs in it though - hit it hard enough and you can make it work, but it's not as easy.
Personally I'm going the 6mm route in the AR (6x45/ aka 6mm - 223) instead of .308 cal for supers, I should meet or beat the 300 Hamr with 95gn bullets in terms of velocity , but I'll be shooting long for caliber bullets with higher BCs (straight weight matching to compare velocities, I know that's not the ideal weight for 300 Hamr). The Hamr will have to use the 130s to catch up to my bullets in desgign, at which point it'll be running slower.
