6br bbl Length /twist for 600?
- Thread starter SBH
- Start date
T
tenring
Guest
I have several Bartliens, and they are great, but know nothing about the gain twist barrels. You need to select your desired bullet before determination of twist. I like the 105-108 gr. bullets, which require a slow twist, 7 - 9. Barrel length depends on balance, and whether you want to squeeze the last fet feet per sec of MV from it; usually 24 0- 26" barrel will do.
Stephen
On the westcoast a 8 to 8.5 twist barrel 28-30 inches long has been doing real well for just about everybody using 100-108 gr bullets.Right now Berger seems to be making some very good bullets as is Clay Spencer.His 103's just won the NBRSA 600 Yard Nationals in april.
If you go to the match results forum below I have posted the top 20 list from the Nationals and alongside it is the cartridge used.
Lynn
On the westcoast a 8 to 8.5 twist barrel 28-30 inches long has been doing real well for just about everybody using 100-108 gr bullets.Right now Berger seems to be making some very good bullets as is Clay Spencer.His 103's just won the NBRSA 600 Yard Nationals in april.
If you go to the match results forum below I have posted the top 20 list from the Nationals and alongside it is the cartridge used.
Lynn
C
Clifdweller77
Guest
B
bkluke
Guest
I haven't heard of any of the long range guys useing the gain twist. I think that is more for the short range stuff (100 to 300) yards. I would go with the straight 8 twist. I my self, would order a 31 inch barrel, so after machineing, it would finnish at 30. With the longer barrel you will be able to rechamber, once the throat has eroded. It beats buying another barrel. You will be able to get many rounds on one barrel, however the throat will erode. On the taper, I go with a palma taper and have the final weight to be 7 to 7.5, so I can stay under the 17 lb. light gun rule. Bartlein can help you on that, they are very helpful. Keep us posted on your bulid. 
Good luck,
Brian
Good luck,
Brian
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gt40
Guest
What is the "gain twist"? I've never heard of it.
gt40
gt40
What is the "gain twist"? I've never heard of it.
gt40
A rifle barrel which "gains" in twist rate.
A rifle barrel which may start out at 0" twist and end up at 10" tpf.
Right now there's a surge of interest in short-range BR barrels which gain an inch or less.
I find them intriguing, I intend to test a bunch of them over the next few years. I have one 6MM which goes from 8" to 7.4" which is a failure. But it does blow up bullets good!
The effect of accelerating the rotation is speculated by some to act as a "choke," by others to have an effect on vibrational characteristics..... maybe "ironing them out"......
Logically neither is true IMO since the bullet is already accelerating on BOTH fronts....... but hey, it's something to try.
al
GT40
On the westcoast some of the guys are using a much smaller gain in there gain twist barrels.They want to keep adding to the bullets engraving but so much as to create failures.I have heard rumors of guys going from 8.6 twist initially down to 8.5 twist at the muzzle.This is supposed to keep the bullet under a load for its entire trip down the barrel.
I am sitting on the sidelines for now.
Lynn aka Waterboy
On the westcoast some of the guys are using a much smaller gain in there gain twist barrels.They want to keep adding to the bullets engraving but so much as to create failures.I have heard rumors of guys going from 8.6 twist initially down to 8.5 twist at the muzzle.This is supposed to keep the bullet under a load for its entire trip down the barrel.
I am sitting on the sidelines for now.
Lynn aka Waterboy
I've got a .30 cal in the works that gains a full 1" twist in 32" and hope to have it up and running in a few weeks. Ron Tilley
F
flatlander
Guest
After the NRA changed their Palma rifle rules to allow 223 bolt rifles, I gave some thought to building a 223 around a 6.5tw bbl. to shoot Berger 90 VLDs. However, my last experience with a 6.5tw 223 involved tumbling & exploding bullets - both Nosler & Sierra 69s at 200, and JLK 80s at 600. After reading the PS article on Bartlein's gaintwist bbls., I ordered a std. Palma contour with constant gain from 8 at the breech to 6.5 at the muzzle, with a finish length of 30". Throat erosion has also been an issue with straight 6.5tw. bbls., and I have hopes that starting out at 8tw. will mitigate that somewhat.
While waiting on the barrel, I bought an Eliseo R5 tubegun kit & a Pierce TG action with two bolts - one with a 223 face, the other a 308. Right now, it's wearing a 28" 6mm (.236" bore) 8tw Krieger in Rem Sendero contour chambered for 6BR with .120" freebore, which I'm shooting in NRA across the course HP matches. It's slightly more than somewhat humbling trying to shoot the rapids with a bolt gun after a dozen or more years of shooting AR15 service & match rifles, but it's a hoot, and I'm having fun with it.
Only time will tell whether the gaintwist will work with moly'd 90 VLDs, but from past experience, I expect to get 2900+fps with the 90s using N550. Should be interesting at 1000yds.
While waiting on the barrel, I bought an Eliseo R5 tubegun kit & a Pierce TG action with two bolts - one with a 223 face, the other a 308. Right now, it's wearing a 28" 6mm (.236" bore) 8tw Krieger in Rem Sendero contour chambered for 6BR with .120" freebore, which I'm shooting in NRA across the course HP matches. It's slightly more than somewhat humbling trying to shoot the rapids with a bolt gun after a dozen or more years of shooting AR15 service & match rifles, but it's a hoot, and I'm having fun with it.
Only time will tell whether the gaintwist will work with moly'd 90 VLDs, but from past experience, I expect to get 2900+fps with the 90s using N550. Should be interesting at 1000yds.
LarryBartholome
Member
Gain Twist
Stephen,
FWIW, while not 600y BR or 6mm, I shoot a 6.5 Bartlein Gain Twist (9.188 to 8.25 in 30). I shoot F-Class with in chambered for a 6.5-284. It shoots as well or better than the other 4 Bartlein’s I have, which means very well. No fouling, easy cleanups. Other team members of mine have been very happy with theirs also. I am waiting on a 7mm gain to be chambered. I would not hesitate to try one.
Stephen,
FWIW, while not 600y BR or 6mm, I shoot a 6.5 Bartlein Gain Twist (9.188 to 8.25 in 30). I shoot F-Class with in chambered for a 6.5-284. It shoots as well or better than the other 4 Bartlein’s I have, which means very well. No fouling, easy cleanups. Other team members of mine have been very happy with theirs also. I am waiting on a 7mm gain to be chambered. I would not hesitate to try one.
M
MARKS
Guest
Stephen,
I would stay with proven barrel twist 8.5 to 8 tw, in HV contour. I don't pay extra for barrel length. get them as they come, and tell the smith to leave it as long as he can. it will be about 28". The Berger 105gr VLD have set most IBS 600 ys records. The 108 BT are coming on strong also.
Mark Schronce
I would stay with proven barrel twist 8.5 to 8 tw, in HV contour. I don't pay extra for barrel length. get them as they come, and tell the smith to leave it as long as he can. it will be about 28". The Berger 105gr VLD have set most IBS 600 ys records. The 108 BT are coming on strong also.
Mark Schronce