6mm Creedmoor barrel twist

[branson1369]

Beginning the long wait/planning for 6CM build so far Stiller Spectre action and JAE 700 ordered. Given lead times trying to time parts to minimize CFO (alias wife) blowback......... Build will not be cheap for sure

Now trying to determine barrel twist/contour (likely either a Bartlien/Brux blank). Feedback on what folks are running woul help. Planning on 105 gr Berger hybrid and/or Hornady 105 gr hpbt

 

[Cinch]

7.5-8 would be perfect. Mine will be in the works here shortly...

 

[Greene]

Run a Bartlein 8 twist with 105 hybrids. Very accurate.

 

[JGorski]

No need for a 7.5 twist, Im running a 8 twist Bartlein, will stabilize a 115DTAC with no issues.

 

[Barney88PDC]

8 twist would work fine. 7.7 twist would work fine. GAP uses a 8.5 to 7.7 gain twist on their team rifles.

 

[branson1369]

Great feedback thanks

 

[Frank Green]

I'm running a 1-8 twist on mine. Don't shoot anything heavier than a 108gr. type bullet.

The 115DTAC's are probably o.k. but if you want to run 115 Berger VLD's I would suggest a 1-7.5 as a min. for those.

Later, Frank
Bartlein Barrels

 

[branson1369]

I'm running a 1-8 twist on mine. Don't shoot anything heavier than a 108gr. type bullet.

The 115DTAC's are probably o.k. but if you want to run 115 Berger VLD's I would suggest a 1-7.5 as a min. for those.

Later, Frank
Bartlein Barrels

Likely to stay with the 105 gr Berger/hornadys

 

[JGorski]

I'm running a 1-8 twist on mine. Don't shoot anything heavier than a 108gr. type bullet.

The 115DTAC's are probably o.k. but if you want to run 115 Berger VLD's I would suggest a 1-7.5 as a min. for those.

Later, Frank
Bartlein Barrels

Frank, The 115VLDs have a .545bc vs .585bc for the DTACs, wouldn't the VLDs stabilize before the DTACs?

 

[valkyries]

From what I understand it depends on the length of the bullet not so much the weight. I have a 1 in ten twist .243, no problems up to 100 grains.

 

[Garyc]

8 twist

 

[Frank Green]

Frank, The 115VLDs have a .545bc vs .585bc for the DTACs, wouldn't the VLDs stabilize before the DTACs?

Length dictates twist not bullet weight. Usually the heavier the bullet the longer the bullet but not always the case.

According to my numbers the VLD's at 3000fps need a min. of 1-7.77 twist. I don't like running my stuff on the ragged edge. Yes a 1-8 might work but you start throwing in factors like temp., elevation, velocity etc....all play a part.

Later, Frank

 

[Frank Green]

Likely to stay with the 105 gr Berger/hornadys

Use the 1-8. I'm shooting Hornady 105's. and Berger Hybrid 105's and even have some Berger 105 VLD's as well.

Later, Frank

 

[branson1369]

Use the 1-8. I'm shooting Hornady 105's. and Berger Hybrid 105's and even have some Berger 105 VLD's as well.

Later, Frank

Thanks

 

[JGorski]

Length dictates twist not bullet weight. Usually the heavier the bullet the longer the bullet but not always the case.

According to my numbers the VLD's at 3000fps need a min. of 1-7.77 twist. I don't like running my stuff on the ragged edge. Yes a 1-8 might work but you start throwing in factors like temp., elevation, velocity etc....all play a part.

Later, Frank

If that's the case the DTAC is longer by about .005" by laying the DTAC(1.304") over the picture in the Berger foldout, and the SG on Bergers website shows 1.48, close enough for me I guess.
http://www.bergerbullets.com/litz/TwistRuleAlt.php

 

[6Dasher]

Hi,

I have a 7.75tw but 115DTACs won't group (1" and up). The 105 Hybrids group like crazy though at around 0.25-0.3 moa without effort. Sea-level and moderate temps of 0-30°C.

Waiting on a 7.5tw blank to see if that helps with the DTACs as I have 2500 of them and seems a waste to resell them.



Jim

 

[JGorski]

Hi,

I have a 7.75tw but 115DTACs won't group (1" and up). The 105 Hybrids group like crazy though at around 0.25-0.3 moa without effort. Sea-level and moderate temps of 0-30°C.

Waiting on a 7.5tw blank to see if that helps with the DTACs as I have 2500 of them and seems a waste to resell them.


Jim

Is that in your Dasher or Creedmoor? I shoot the DTACs in my Creedmoor, they shoot fine so far.

 

[Frank Green]

If that's the case the DTAC is longer by about .005" by laying the DTAC(1.304") over the picture in the Berger foldout, and the SG on Bergers website shows 1.48, close enough for me I guess.
http://www.bergerbullets.com/litz/TwistRuleAlt.php

Some guys get them to work and some not. Again I think a 1-8 it is on the ragged edged. Where you shoot (elevation), temperatures, velocities etc...play a part.

It's like some guys who shoot a 6BR and they run twists as as slow as 1-8.5. Some guys can get the 107's to shoot and some cannot.

I also think the 115gr. bullets are varying to much from lot to lot for consistency. One lot seems to group/shoot really well and the next lot won't or are just o.k. I had a old 1-8 twist barrel chambered in 6mm Rem. First loads I tried with the 115DTAC's shot just under a 1" or right at a 1" groups but the Bergers went over an inch but the 107's and 105's just pounded nails. My velocity was only 2900fps. for the 115's. The 115 DTAC's I had were a older lot as well and the tips of the bullets left a lot to be desired as far as consistency goes. I also have some 120gr. SMK's that were prototype bullets. All they are is a stretched out 107. The 120's were dropped if I remember correctly because of consistency and they were trying to get more out of that jacket then it was capable of etc....and it just wasn't working out. The 115's type bullets I'm starting to lump into the 90gr. bullet class of the .223. It kinda becomes a dedicated gun and round combo for some guys.

If you can get the 115's to shoot in a 1-8 twist and your happy with them you got nothing to lose.

Later, Frank
Bartlein Barrels

 

[6Dasher]

[MENTION=59501]JGorski[/MENTION]: I'm shooing a 31" 6x47 Lapua using H4350; getting 3150fps with the 105 Hybrids, around 3050-3100 for the DTACs.

 

[JGorski]

When you guys mention you're getting 1" or more with the DTACs, is that at 100 or 300yds? I've got to assume 300 because my best group with them went 1.285"(1st group ever shot with them) on a slightly windy day, and that was 300yds.

 

[6Dasher]

At 100m for me, so not stabilized in the 7.75tw barrel in my case.