Stability Calculators and the 6.5

[Bill Norton]

For all you 6.5 guys out there shooting 140 grains and up. Multiple Stability calculators say that the 1:7 twist performs better than the 1:7.5 and I have no damn idea if I am splitting hairs at this point. I'm about to pull the trigger on a barrel.
What say you? and GO!

 

[243winxb]

7 twist. Said the calculator.

 

[LoonWulf]

You need to be shooting some real pencils to need a 1-7 twist in a 6.5, but if I your going to shoot are really long heavy bullets I'd just go with that.
All of my 6.5s have been 1-8 or 8.6(Mauser m18).

 

[Garandimal]

You need to be shooting some real pencils to need a 1-7 twist in a 6.5, but if I your going to shoot are really long heavy bullets I'd just go with that.
All of my 6.5s have been 1-8 or 8.6(Mauser m18).

My 6.5x55 RUGER African - shoots 140's into a bug-hole.

Guess it missed the "calculator" memo.

Lucky.

8>)




GR

 

[FL-NC]

6.5 CM? My RAR is 1:8 and shoots sub MOA with factory 140's.

 

[LoonWulf]

My 6.5x55 RUGER African - shoots 140's into a bug-hole.

Guess it missed the "calculator" memo.

Lucky.

8>)




GR

Mine have been fine with everything upto the 147eldms, but there are some heavier bullets out that might want for a bit more twist. I think the standard 1-8s as much as necessary, but if someone wants a 1-7 that should work as well.

 

[jmr40]

Anything 140-147 gr I've shot were fine in my 8 twist. Anything heavier is a hunting bullet, and even if heavier, not as long.

 

[LoonWulf]

Anything 140-147 gr I've shot were fine in my 8 twist. Anything heavier is a hunting bullet, and even if heavier, not as long.

There are the 153a-tips and we're 150smks, both of which ARE supposed to be ok in 1-8s....I'm not sure if there are others, seems likely tho.

 

[taliv]

If you’re looking at a calculator litz is involved with, keep in mind there may be a difference between stable enough to poke a round hole in paper, and stabile enough to achieve the BC advertised

 

[Goosey]

You will have to be shooting the longest available bullets to require a 1-in-7" twist.

If you’re looking at a calculator litz is involved with, keep in mind there may be a difference between stable enough to poke a round hole in paper, and stabile enough to achieve the BC advertised

Seems like Litz recommends SG of 1.5 or higher for an unhampered BC.



For a Berger 153.5 LRHT at 1.514" I get SG 1.5 at 1-in-7.39" twist, and SG 2.0 at 1-in-6.40" twist (Berger recommended minimum twist, 1-in-8").


For a Cutting Edge 143 MTAC at 1.501" I get SG 1.5 at 1-in-7.56" twist, and SG 2.0 at 1-in-6.55" twist (Cutting Edge recommended minimum twist, 1-in-6.5").