Super Fast Twist Barrels for Hammer Bullets

Lilja will do a 3 groove 7 twist in .277 but only a 7.5 in 6.5mm.

KS Arms in Canada says they'll go as fast as a 6.5 twist in anything from 20 cal to 50 cal. Very popular barrel with ELR guys right now.

PacNor uses buttons so they normally cut abnormally fast twists (4 twist 308 cal anyone?), but they don't have a 6.5mm faster than 7".


Off topic time, but since Steve is here - PacNor did a 6 twist 36" 308 cal blank for me that is going to send a 101gn Hammer into orbit at Mach Jesus when I get it screwed on 🤣 I'll be aiming at the 100 yard line but likely won't have a clue where they're headed once they're out!

The real purpose is 240gn CEs that require a 6 twist on paper, even with the stupid velocity I'll get from the long tube and 300 LIMP chamber. Hopefully I'll twist a jacket in half on a 245 Berger EOL and will be able to say I found the end of the road for cup and core. My hunting load will most likely be a 124HH a case of Trail Boss, probably good to mimic a mild 30-06 load of at least 3000 FPS. 🤣
K &S are my neighbors and darn fine people making exceptional products. Father and Son (plus staff)... long, long time in business! You all should give there actions and barrels a good look!
 
There is a point where bullet length hits about 6x caliber in length. At this point dynamic stability becomes very difficult and sometimes you just can't twist enough to overcome it. Particularly the higher the velocity gets. Technically all bullets have a speed limit where they will become dynamically unstable. Some bullets should have deployable fins. When we worked with @HARPERC 's 6.5 Ultracat the goal was to run a bullet around 160g. We designed a bullet that was pushing 2" long and about 155g. It was pushing a stability factor over 2.0sg calculated by the Miller formula. It shot well until we hit 3200 fps where it started swapping ends inside 200y. We have seen this happen with bullets that maintain sub half moa out to 1300y and then start tumbling even though they are very ballistically stable and still 800 fps above the sound barrier.
good info Steve!. Africa in Dec, interested??
 
I'm really curious about an increase in terminal performance of Hammer and Cutting edge bullets. With faster twist barrels.

I see bullets like Makers, Barnes and discreet Ballistics bullets are benefiting from high twist rates. 1:3 for 8.6 and 1:5 for 300BLK. The 8.6 with a 1:3 is spinning a 210gr Barnes 500k RPM

I myself am looking at a 416 Rigby with a 1:8-1:9 barrel. It will double the RPM and quadruple the rotational KE over the 1:16.5


I went off on a tangent. Anyways just curious terminally how faster twist rates and non conventional bullets work together
 

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