Ordering 6mm barrel
- Thread starter Tony1320
- Start date
Because of the 115 and the 110 Sierra, yes. They have in between twists as well, like 7.5, or 7.7. You should be fine with an 8, but a 7 or 7.5 won’t hurt anything and will allow you to shoot whatever you like down the road. 4 or 5r doesn’t matter, it’s a personal preference.
I run 26" Bartleins in GAP #6 with a 7.7 twist for 6 Creedmoor. Bear in mind that if you're ordering a barrel blank, it will need to be a little longer than what you want your finished length to be. IE: If you want a 26" finished barrel, don't order a 26" blank.
I run a 28" Criterion 6BR pre-fit with a 1-8 twist rate and a bull contour (tapers from 1.055" to 1", effectively a 1" straight contour).
It should be noted that the 115 DTACs are designed to work in a 1-8 twist barrel (according to David Tubb himself), and do not require a 1-7 twist or other faster rates. My current load for DTACs is 29.6gr Varget and .020" off the lands, which gives me no apparent stability issues and shoots .46 MOA with a velocity average of 2840 fps (do note that my chamber is slightly shorter than SAAMI spec since it was headspaced off virgin Lapua brass, YMMV on speeds).
For me the 28" length worked well to give a little extra speed to the straight BR, and since I was already used to shooting matches with a 26" barrel and 9" suppressor the extra length wasn't a concern (I can get identical length just using a 7" suppressor instead).
It should be noted that the 115 DTACs are designed to work in a 1-8 twist barrel (according to David Tubb himself), and do not require a 1-7 twist or other faster rates. My current load for DTACs is 29.6gr Varget and .020" off the lands, which gives me no apparent stability issues and shoots .46 MOA with a velocity average of 2840 fps (do note that my chamber is slightly shorter than SAAMI spec since it was headspaced off virgin Lapua brass, YMMV on speeds).
For me the 28" length worked well to give a little extra speed to the straight BR, and since I was already used to shooting matches with a 26" barrel and 9" suppressor the extra length wasn't a concern (I can get identical length just using a 7" suppressor instead).
I also run 115 DTAC in a Criterion 243 AI with a 1:8" twist. They will stabilize at sea level standard conditions in a 1:8" twist. If your DA becomes negative they do not do well. They lose a lot of BC as well as doing some wonky stuff in the wind. I discovered this when prepping for a January match when it was 10 degrees. As long as the DA is above zero they hammer for me. When it gets cold I do have issues though. I just had to screw on a new barrel and ordered a 1:7.5" twist to replace it for this reason.
105 hybrids, I'd go 1:8. 1:7.5 if you're scared or think you'll want to try heavier.
5r seems to be nicer to bullet jackets. Most of the normal-velocity (under 300k rpm) exploding bullets I've seen mentioned happened in 4 groove barrels. Only really an issue if you have a tight, firecracked, or very dirty bore.
Profile, I prefer #4 contour up to about a medium Palma. Never understood why guys go so heavy.
5r seems to be nicer to bullet jackets. Most of the normal-velocity (under 300k rpm) exploding bullets I've seen mentioned happened in 4 groove barrels. Only really an issue if you have a tight, firecracked, or very dirty bore.
Profile, I prefer #4 contour up to about a medium Palma. Never understood why guys go so heavy.
Perks of living up where the elevation is a mile is that it could be 20 below and I'd still have a positive density altitude!
More weight is an advantage for many styles of competition that don't have weight limits and don't require you to pack your rifle long distances during the event. It serves to reduce the movement of the gun under recoil and increases the ability of the barrel to effectively dissipate (more surface area) and tolerate (more metal to soak it up) heat.
I run a 28" 7.7 twist 6mm Creedmoor with the 108 ELDs and a 26" 8.5 twist .243 with the 105 BTHPs. Both are very accurate. Used to run a 7.5 twist .243 years ago with the 115s and it worked great. I wouldn't go any faster unless you plan to shoot 110s. If just using the 105s then a 7.7-8 would work well.
The Creedmoor is a med palma contour and the .243 is a M24/40. I like the med palma better. I use it on my 6.5 now too. Easier to move around stages when changing positions and with brakes the recoil is tamed anyways so I see no need for extra weight. Rifles are about 15-16 pounds so plenty heavy to steady them in positions. I have used heavier barrels in the past when not running a brake but don't see any advantage now.
The Creedmoor is a med palma contour and the .243 is a M24/40. I like the med palma better. I use it on my 6.5 now too. Easier to move around stages when changing positions and with brakes the recoil is tamed anyways so I see no need for extra weight. Rifles are about 15-16 pounds so plenty heavy to steady them in positions. I have used heavier barrels in the past when not running a brake but don't see any advantage now.
1-7 to 1-7.5 with the BR since your velocity is lower. Pick your length, heavy Palma is about as light as I'd go. I haven't found a situation yet where added weight was a bad thing. My first dasher was a 1-7.5 @ 26" in marksman contour, second was a 1-7 @ 24" M24 contour, and third is 1-7 @ 26" MTU (actually a HV with some shank removed).
Don't sweat the groove pattern.. wont tell a difference from behind the scope.
Berger says 1:7
Don't sweat the groove pattern.. wont tell a difference from behind the scope.
Berger says 1:7
Berger says 1 in 7 for their 105 Hybrids, but I've never heard of anyone having issues with a 1-8 twist using any bullet besides the Berger 115's and the Sierra 110's.
Thanks for the input everyone I'm going to go with a 7.5 that will be a happy medium
Is that a recent box? Because Berger says 1-8 on their website
Is that a recent box? Because Berger says 1-8 on their website
Yes, sometime last summer. Their website lists the 'minimum' twist for proper stability.. box indicates 'optimal' twist.
You'll be fine with a 1:7.5.. seems like they are almost easier to find than 1:8's anyways.
