7BR

[Fuj]

Plug in some numbers from the actual bullet and if I'm reading it right,
16.5" twist is optimal. Note that this barrel was not intended for this bullet
but for a range between 130/150s. I shot the 130 Sierras for years in the
12 twist Douglas and Harts but, Sierra stopped production of them a few
short years ago. I used 3350 FPS as a median. where this barrel seems to
like them. And again, no seating depth tests done yet. The Miller formula
put's it at about a 16 twist. Always something to play with.

 

[James Kelbly]

Cleaning out my father's reloading room and I found 56 pieces of original 7BR Remington brass (1980's) if anyone is interested in them.

Jim

 

[rsmithsr]

i want to thank everyone that posted on what had been done..i learned...to stick with 30br and 6ppc..i have neither the time nor the money to play with a limited resource round.

 

[R.G. Robinett]

Plug in some numbers from the actual bullet and if I'm reading it right,
16.5" twist is optimal. Note that this barrel was not intended for this bullet
but for a range between 130/150s. I shot the 130 Sierras for years in the
12 twist Douglas and Harts but, Sierra stopped production of them a few
short years ago. I used 3350 FPS as a median. where this barrel seems to
like them. And again, no seating depth tests done yet. The Miller formula
put's it at about a 16 twist. Always something to play with.

Fuj - the Border Barrels graph is showing us, that, at any MV at, or, above 1250 FPS, a 1:16" twist will produce Sg1.5 while, with MV of 3K FPS, a twist rate of roughly 1:16.6" will deliver Sg1.5, and @ 3.5K MV, a 1:16.75" the same . . . in real-world, no difference. This graphic displays, how, with appropriate twist rate, Sg is little affected by MV velocity, which provides almost useless value. RG

 

[Al Nyhus]

This graphic displays, how, with appropriate twist rate, Sg is little affected by MV velocity, which provides almost useless value value. RG

This, X's 1,000 ^^^^^^^^ -Al

 

[Fuj]

Bringing this thread back to life. I want to put what's going on in the skunk works and not
to lose any already posted data......Yes I'm building a 7BR. Since the end of Tack Driver 6
I've been like a squirrel gathering and storing nut's for a special build. This whole deal always
revolves around the bullet problem. I went a route unheard of. I took a few prototype bullets
I designed and had Hammer bullets run them on one of their Swiss lathes.....Yes, it's solid copper.
I'm by passing a lot of tradition and looking at something fresh. If reading this, and think ol' Fuj
has been drinking again, the bullet is even a rebated boat tail. I took a few samples down to TD6
and passed em' around...... Ether way, I have needed items coming in weekly, and over the next
two months my madness will gel. I do now have 500 of the bullets in house for testing when I
have a rifle put together. Lilja is doing a barrel for me and that will be the biggest hold up......
Already have a revision design to be run before match season starts......Prototype RBT solid is
.903" long at 92 grains. I did initially run a few out of the 7.2 GreedMore to see how evil the
velocity could get safely. 3608 fps is where I stopped with N-135. In the 7BR cases that Peterson
sent me, I stocked N-130......There will be a lot more twists and turns also in other areas that will
buck the norm. It's what I do. This will be more then a 3 beer job.......Thinking of calling this one
the 7.2 Copperhead even though it's still the 7BR case......

Prototypes