Overlooked: 7mm 131 Heavy Hammer

[BFD]

In the continuing endeavor to shoot Hammers out the AR platforms I guess I've suffered an extended "Bald moment" and not zeroed in on this dandy, the 131 Heavy Hammer? Looks like it's got the profile advantageous for use in COAL magazine restricted guns like the ARs. Comparing the 131 HH with the 131 Heavy it looks like the Heavy version is also a bit shorter, which is good, but what else is different about the bullet? @Steve Davis

 

[LightTheTower]

I had to use it in my A-bolt 280 because of slower than advertised twist. I’m sure 6 pdr bands instead of 4 gives the rifling more bite.

 

[BFD]

I had to use it in my A-bolt 280 because of slower than advertised twist. I’m sure 6 pdr bands instead of 4 gives the rifling more bite.

Does adding bands increase or decrease the bearing surface? I should think the extra 2 bands further decreases it...

 

[LightTheTower]

Does adding bands increase or decrease the bearing surface? I should think the extra 2 bands further decreases it...

I assume it increases it. Just looking at the 131 HH and HHH side by side, I envision the creation of the Heavy as having added a drive band at the bottom (decreasing boat tail length) and at the top (decreasing nose length.

 

[BFD]

I assume it increases it. Just looking at the 131 HH and HHH side by side, I envision the creation of the Heavy as having added a drive band at the bottom (decreasing boat tail length) and at the top (decreasing nose length.

Daggum. Maybe those two in tandem balances out the bearing surface?

 

[LightTheTower]

Daggum. Maybe those two in tandem balances out the bearing surface?

I don’t know… I feel like the longer nose of the HH leaves .284 diameter at the same distance off the top drive band, or maybe even sooner, than on the Heavy.

 

[BFD]

I don’t know… I feel like the longer nose of the HH leaves .284 diameter at the same distance off the top drive band, or maybe even sooner, than on the Heavy.

The HHH bearing surface is certainly closer to the nose than the more needle like HH. That is always a good thing for an AR bullet. It's why the Sierra SMKs shoot so good across the board in ARs. Sierra came out with the Tipped Match King and while reports of precision diminished, the terminal effects increased. (Those Sierra terminal results still can't compete with Hammers)