6.5 Creedmoor barrel length.

[Rob01]

Let me just start by saying I have no experience reloading and only shoot factory ammunition at this time. Perhaps I am missing something with the barrel length discussion but doesn't the amount of contact surface of the bullet play into the velocity out of a particular barrel with a fixed charge? I understand that when reloading the charge can be tailored to the resistance of the bullet in the barrel and the length of burn available in the length of the barrel but with factory ammunition aren't these things fixed? Wouldn't a bullet with less bearing surface (in this case the lighter bullet) in the barrel produce higher velocities? Isn't this why I hear the Berger 215 Hybrids produce higher velocities than the 210 VLD/s? It would seem completely plausible to me that the fixed burn of the factory powder load would reach a point of diminishing returns. This point would obviously vary depending on powder burn rate, resistance of the bullet, etc. Because the debated barrel length test was using a fixed factory load that was not tuned to the varying barrel length each time it was cut would it not simply show the optimal barrel length for that exact load (lot number, powder, bullet, etc)? Clearly if max velocity is reached with a particular charge and bullet out of say 24 inches of the barrel, to utilized the potential velocity of more barrel length the load would need to be modified, would it not? The way I understand it the optimal barrel length then would be different for a reloader than a factory ammo shooter. Maybe I am missing something but that is what seems logical to my untrained ear.

The 142 load was not a factory load but a hand load. The barrel would be much, much longer before you started seeing velocity loss.

 

[367CSM]

JP makes their rifles with 22” barrels in 6.5 Creedmoor. You Tube video shows 7 out 10 shots at 1625 yards! FYI

 

[JBattles]

I have had a 24" and am currently running a 26" M24 contour. Great barrel and heavy profile.

 

[SMC21]

Adding my 2 cents:

22” bartlein
Shooting factory 6.5 Hornady 140-eld Match only
FPS has hovered around 2668

If I had to do it again, I’d go 24” mostly for the balance of the gun and that’s really it. It’s a tad ass-heavy.

 

[TACC]

Lots of great info and experience here

 

[bobby1028]

Very difficult to give a hard and fast answer, too many variables...barrel maker, rifling, many factors come into play. If I were to make an educated guess I'd say minimum bbl length of 24 inch, minimum. Don't know of too many tests other than 22lr where any less barrel length showed any significant velocity gains.

 

[6MT]

I have a Kreiger #11 straight pipe (1.25”) finished at 28” (1:8”) and the big Heathen brake. I built this for distance. And with the 140gr class of bullets, it does pretty good out to a mile (2905fps).

 

[HogsLife]

I'm going to be having my 6.5 Creedmoor chambered this week. It's a M24 contour bartlein barrel and defiance action. I'm wondering if there is an optimal barrel length for this cartridge. By the way...It is an 8 twist. Thanks for any input.

If you’re not worried about lugging it around, go long with it. 26”-28”. If you want a shorty, you’re just gonna lose some velocity. Somewhere in the vicinity or 25fps per inch of barrel length is a good guesstimate. Built My kiddo a 6.5CM with a 16.5” barrel and a 6.5PRC in a 22”.

 

[spottsvegas_65]

I'm going to be having my 6.5 Creedmoor chambered this week. It's a M24 contour bartlein barrel and defiance action. I'm wondering if there is an optimal barrel length for this cartridge. By the way...It is an 8 twist. Thanks for any input.

I just had a 29” bartlein mtu blank chambered and after all the work, it ended up being 28.5”. I debated on cutting it down to 26” but I decided to leave it and see how it shot. This thing is awesome. I’m glad I left it long. For the bench and prone shooting I do, weight wasn’t a concern.

 

[Malum Prohibitum]

Hi Rob,

I appreciate your response. The ammunition wasn't mixed and I published the results I obtained, that is how "science" works (and I use that term loosely). You record the data you get, not the data you want to get. The lighter load did speed up, heavier didn't. A better argument would be based on sample size (number of rounds fired and barrels (1) my background is in stochastic modeling- I actually wrote models for far more complex systems and we would test them against empirical data sets, when the model didn't match we would work on making a better one) or the quality (or lack of quality) of the barrel. I don't disagree that you would think longer barrels go faster, I do too. What you have is called an anecdotal account based on your experience, which is certainly valid (guys like me and you have access to far more resources than most shooters). Have you ever cut the same 6.5 creed barrel with the same ammo at the same temp? What does that data set look like? As far as people misinterpreting what I write (or you write), well, that is the internet. For what its worth we had similar diminishing returns over a mix of different cartridges and barrels.

For a little bit of history on why I started those posts it was to prove an article in a print magazine wrong. If you want I'll PM you the article, but basically someone claimed NO velocity gain in a 300 WIn Mag over 20" IIRC.

I guess we will agree to disagree.

Thanks,
Bill

Thanks for doing it. I found your article very interesting.

As to the sample size, well, next time use 40,000 barrels and do it properly!