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Twist for 153.5 in 6.5 PRC

ExPiney

Gold $$ Contributor
Current thoughts on whether or not you need a 7.5 to stabalize 153.5 Bergers in a 6.5 PRC. 26" barrel, powder will be 565 and maybe others. Target shooting only. This gun will likely only shoot Hornady 147 or the Berger 153.5. I have other 6.5's for lighter bullets.

Thanks.
 
Depending on barrel length, velocity around 2900 should be easy. So the 153 in the berger twist calculator for the 153 at 0 degrees and sea level says about 7.5 should be perfect (1.46 stability factor). A ton of barrel makers now do 7.5 twist pipes too if your not getting it from a manufacturer who can do custom twists.
 
I wanted to look at something with that Berger twist rate calculator, but I can’t find it, seems like maybe it’s removed.
 
darkangel_r2 said:
bergerbullets.com

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.
bergerbullets.com bergerbullets.com

its still there
Click to expand...
Thanks. I couldn’t find it in the menus or by searching. I think when they added the ballistics calculator they accidentally eliminated The tracks to the stability calculator so that you need the URL to find it.

So, you can shoot that bullet in an 8 twist but the calculator says marginal stability at sea level, and that is true whether you are at Creedmoor or PRC velocities. If you only shoot at 3-4000ft plus, 8 twist is golden.
 
Comtnman said:
Current thoughts on whether or not you need a 7.5 to stabalize 153.5 Bergers in a 6.5 PRC. 26" barrel, powder will be 565 and maybe others. Target shooting only. This gun will likely only shoot Hornady 147 or the Berger 153.5. I have other 6.5's for lighter bullets.

Thanks.
Click to expand...
Im asking the same question. Im building a new 6.5 PRC. My Bergara Premier Pro is a 26 inch 1-8 twist.It shoots 147gr Hornady fine but Im wanting to shoot heavier Berger bullets.
What di you buy and how does it shoot? Thanks
 
bubbalo7 said:
Im asking the same question. Im building a new 6.5 PRC. My Bergara Premier Pro is a 26 inch 1-8 twist.It shoots 147gr Hornady fine but Im wanting to shoot heavier Berger bullets.
What di you buy and how does it shoot? Thanks
Click to expand...
I know quite a few people shooting Berger 156's for hunting with their 6.5 PRC's and it's working just fine for them. I no long hunt, but I'm shooting Berger 140's and Berger 153.5's and both have done really well for me out of my 1:8 twist.
 
My 6.5x47 bench rest rifle shoots the 153.5 out of an 8 twist very well. 4 inches at 1000 well. I am shooting at ~5000 ft elevation at CRC.
 
Im still working on fine tuning the 156 in mine but its an 8 twist and been okay so far. I need to retest a load and then will try at 600 yards to see if wtill good.
 
Comtnman said:
I went with a 7.5 twist though, just to be safe.
Click to expand...
I've also shot some of the 153 A-Tips out of my 1:8 and they too did very well. I was worried they might blow up at the higher charges I was using from the things I've heard, but so far so good. Am not sure how they'd do with a 7.5 or faster twist???
 
I've got three 6.5CM up and running. Two barrels are 7.5 twist and one is 6.75 twist. All have shot great. I've put 140Amax's thru them along with 147's, 150SMK and the 135 and 153 Atips. All 3 of these barrels are 23" finish length.

Really close to getting a 4th 6.5CM up and running. It will also be 23" might be 24" finish. Still have to cut and crown the muzzle and put it on the action. Picked up a nos Savage original left hand silhouette stock and have a late 60's left hand Savage 110 action and basically built the rifle from parts. Savage never listed a silhouette rifle from the factory in left hand. I found the stock on Ebay still brand new and picked it up for a $100. Being a lefty I couldn't pass it up.

I just finally got my 6.5PRC barrel on my F open gun this morning. That's a 7.25 twist. I should be able to get a few rounds on it tomorrow or Saturday. That barrel is 32" finish length. Only bullets I plan on running are the 150smk and the 153Atips.

Later, Frank
Bartlein Barrels
 
Verify with Berger on max RPM. A friend of mine found out the hard way with his 6.5 PRC at a match in Utah....he was having bullets self destructing about 50 yards out. I don't recall all of the details, but he was using heavy Bergers that shot fine at sea level.
 
choprzrul said:
Verify with Berger on max RPM. A friend of mine found out the hard way with his 6.5 PRC at a match in Utah....he was having bullets self destructing about 50 yards out. I don't recall all of the details, but he was using heavy Bergers that shot fine at sea level.
Click to expand...

Sea level vs altitune shouldn't make any different in bullets blowing up. RPM based on twist rate is RPM.

If they stabilize at a given altitude and RPM is a different issue.
 
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