.20 and bullet blow-ups; twist rates and velocity?

[AdamJ]

At what velocity and twist rate would a .20 39 sierra BK or 40 hornady vmax come apart at? Am interested in a little PD popper and wandering what I should go with or avoid. Thanks for the help. Also when a bullet blows-up does it appear like a puff of light whitish-gray smoke about 10-15yds down range?

 

[Phil]

39 Sierra BK`s and 38 Unmussigs over 4500fps.....

Everything A OK..........

12 twist .20 Dasher...


My FAVORITE .20 cal. is a 20PPC 11 twist and 40gr. V-max/39gr BK`s @ around 4000fps.

 

[AdamJ]

how about a 1-9 @ 4000-4100 fps with the vmax and BKs? Is my description of a bullet blow up sound right?

 

[Phil]

Adam,

Possibly........I have NO experience with the 39/40 bullets and a 9 twist, so my answer would just be a guess,not fact...

Phil.

 

[DOGCAPPER]

Puff of light blue smoke 10 to 40 yards out ....First indication is unbeliveable miss on an easy target...
Light bullets in 220 Swift and 6mm Rem...
Hornady blow easiest...But all light varmit bullets are succeptable,,,Exposed lead tip softpoint are easier to destroy than hollow point...
LT

 

[Alycidon]

I found that 40gr Vmax went through the chrono at 3600 but failed to reach a large target backer 100 yards away. At 3500 they shot in the .5s.

Rifle is a 1 in 9 twist 20BR.

I have not chronoed the 39gr SBK yet but they are fine with slightly heavier powder loads. My working load is about 3600 from the feel of it.

I believe its the twist that is killing them rather than the speed, others here and elsewhere drive them to over 4000 fps in 1 in 11s.

A

 

[KevinL]

my own 9 twist brls wont shoot 40 grners or litter.
I dont own a 11 twist yet but will
I love the 20 br with a 12 twist with 39 or 40 grn pills
my 20-250 with a 9 twist WONT shoot 40 grainers I did try some 45s that did better but had to get to the 50 grainers to get any performance
Good luck Kevin