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Super Fast Twist Barrels for Hammer Bullets
- Thread starter nksmfamjp
- Start date
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HARPERC
Well-Known Member
I have a Bartlein 1-6" twist 6.5. They'll make about anything on a custom basis. Slow delivery on those out of ordinary.
Varmint Hunter
Well-Known Member
HARPERC
Well-Known Member
We, @RockyMtnMT, and I were looking at how long/heavy we could make a 6.5 mono perform.What would you shoot through a 6 twist, 6.5mm. Inquiring minds want to know.
Initially didn't work out, may have to circle back at some point.
Currently shooting the 124 Hammer Hunter at around 4000 fps, and it works nicely.
RockyMtnMT
Official LRH Sponsor
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.
RockyMtnMT
Official LRH Sponsor
I will add that the 124g Hammer Hunter at nearly 4000 fps is a piece of cake at 1400y. When we were test firing @HARPERC 's rifle there was a guy cutting firewood across the road that came over to see what we were doing. Offered him to take a shot at the moa rock we were shooting and he hit it 1st try. Never shot anything that far in his life.
QuietTexan
Well-Known Member
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.
www.ksarms.com
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.
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.
1.25"Ø Stainless Steel Barrel blank — K.S. ARMS LTD
All barrels are made here in our facility as ordered from start to finish. For specific requests and technical details such as bore and groove Ø, or twist rate, etc. please email or call us. Cut rifled blanks in 416R Stainless 20 cal to 50 cal 4, 5R or 6 grooves See chart below for caliber
www.ksarms.com
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.
HARPERC
Well-Known Member
I look forward to that thread!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
Me too @HARPERC !!!!
Bghunter338
Well-Known Member
For a 7 twist cut barrel I went with McGowan on my 27 Sherman mag and I'm very happy I did.
I did a quick research on the 6.5 cal 1:6.5" twist for a friend sometime last year. I did not find any other than some barrel manufacturers will make a special run. Below is from Pac-Nor (https://pac-nor.com/barrels/ )
X-Caliber also offers the 1:7"/7.5" option.
Good luck!
Contact Benchmark Barrels they can cut you a 5 Grove cut rifled barrel in any twist you want. Tell them Bill from Grenfell Armouring Service sent you
nksmfamjp
Well-Known Member
- Joined
- Jan 5, 2004
- Messages
- 3,463
Interesting. I wonder if this is really a place for gain twist as opposed to straight twist. It would be nice to have a rifle developed for mono's that wouldn't rip the jacket off std's.
It is my understanding that straight fast twists cause bullets to skid down the barrel ripping a std jacket of….or at least damaging it.
I don't really have any idea about gain twist. Can I start at like 9 twist and finish at 7 twist, or is that too aggressive?
It is my understanding that straight fast twists cause bullets to skid down the barrel ripping a std jacket of….or at least damaging it.
I don't really have any idea about gain twist. Can I start at like 9 twist and finish at 7 twist, or is that too aggressive?
