Barrel length

[olsingleshot]

What is the best barrel length to obtain the best velocity of a 6.5 Grendel?

[37L1]

Best velocity is relative. You will probably get the highest velocity out of a longer barrel.

[Buck2732]

Mine is a 22" it would appear its a slow one, but accurate. It's on a CZ527.

[jeff556]

I've been thinking about some of the same issues the OP has. Perhaps a different way to ask the question is this.

At what barrel length does one hit the point of diminishing returns? For example - and these numbers are all pulled from thin air - if there is a 100 fps increase from 18" to 19" but only a 50 fps increase from 19" to 20" I would say you've hit the point of diminishing returns.

[tackdriver]

Lovey 18" 1:8

[LRRPF52]

I would look at your intended use first. The Grendel case is actually a very high efficiency shape when it comes to burning powder, so it does better than most cases that fit in the AR15, mainly because of being short and wide, with a 30 degree shoulder.

When you look at 10.5"-12.5" speeds, combined with the BC's, they do more than one would think.

If all I was doing was riding a bench or the prone, I wouldn't go more than a 22"-24". For carry guns, I like 18" or less. Across several barrels now, I don't really see a difference between my 16" and 18" with the speeds.

There's a velocity estimator chart in Volume I of the 6.5 Grendel Reloading Handbook series that shows the curve rate for change in barrel length, because it is not linear, so the typical thing you often hear is X fps per inch of barrel length, but that just doesn't hold true on the short (steep) or long end (flat) with any bottleneck rifle cartridge.

[olsingleshot]

Thanks to all for your imput. I plan on doing some long range shooting (targets) plus use it for a whitetail cartridge. I am thinking I will go for 22-24" barrel on an Encore frame.

[terrywick4]

wasn't there a thread where someone was cutting a barrel down and determined that 21 7/8 or 22 7/8 was the most accurate/velocity combo??

[LR1955]

wasn't there a thread where someone was cutting a barrel down and determined that 21 7/8 or 22 7/8 was the most accurate/velocity combo??

Terry:

I would really look at something like this very skeptically. So,this means a 23 inch barrel will show a significant decrease in velocity and accuracy over a 22 7/8 barrel? 1/8 of an inch?

The thing you can bet on with barrels is that the better quality barrels will give better performance than the low end barrels. When I say 'bet', it is what I mean. Probably 80 or 90 percent of the time a high end barrel will show better performance than a low end barrel. If you spend the money on a high end Lilja or Krieger for example, you are almost assured seeing better performance than a Shaw or 'AR Stoner'.

Another thing about barrels is that this improvement in performance is seen at longer distances most of the time. Guys here can easily get sub minute with a Shaw at 100 yards but that Shaw won't dependably hold that performance level at 300 like a high end barrel will.

As for barrel length, get the length that suits the primary purpose of the rifle or carbine. Guys want carbine agility with 1000 yard ability will never get an ideal tool for either purpose.

LR55

[LRRPF52]

wasn't there a thread where someone was cutting a barrel down and determined that 21 7/8 or 22 7/8 was the most accurate/velocity combo??

That was with the 6mm PPC Texas warehouse guys back in the day. It was a 21.75" barrel I think that they found to be optimal for chasing 1-hole 10rd groups typical of the short range benchrest crowd.

[Jackem]

Here's an old article many of you have probably read about some guys shooting inside a warehouse:
Secrets of the Houston Warehouse

Here's a quote of what they discovered about barrel length: "But no bit of information was, Virgil believes, more valuable than a little advice Jim Gilmore passed along. Jim said a barrel MUST be 21 3/4” long for optimum accuracy. That precise length, he stated, sets up a vibration pattern that duplicates well from shot to shot. Virgil faithfully followed that advice on his guns."

Edit; Posted before I read LRPFF52 above ...

Jack

[terrywick4]

DO YOU SEE A DIFFERENCE IN PERFORMANCE FROM LET SAY .3 GR OF POWDER? You bet you do so why wouldn't you see a break-off in accuracy at a certain length/velocity. Harmonics is an important role in barrel performance and accuracy. The start of this thread was Barrel length. And yes according to that thread there was a difference in accuracy in just 1/8 of an inch.

Terry:

I would really look at something like this very skeptically. So,this means a 23 inch barrel will show a significant decrease in velocity and accuracy over a 22 7/8 barrel? 1/8 of an inch?

The thing you can bet on with barrels is that the better quality barrels will give better performance than the low end barrels. When I say 'bet', it is what I mean. Probably 80 or 90 percent of the time a high end barrel will show better performance than a low end barrel. If you spend the money on a high end Lilja or Krieger for example, you are almost assured seeing better performance than a Shaw or 'AR Stoner'.

Another thing about barrels is that this improvement in performance is seen at longer distances most of the time. Guys here can easily get sub minute with a Shaw at 100 yards but that Shaw won't dependably hold that performance level at 300 like a high end barrel will.

As for barrel length, get the length that suits the primary purpose of the rifle or carbine. Guys want carbine agility with 1000 yard ability will never get an ideal tool for either purpose.

LR55

[terrywick4]

And someone on this forum (a while back before the site was hacked) was bored one day and was cutting one of his barrels down and concluded that there was merit to this.

Here's an old article many of you have probably read about some guys shooting inside a warehouse:
Secrets of the Houston Warehouse

Here's a quote of what they discovered about barrel length: "But no bit of information was, Virgil believes, more valuable than a little advice Jim Gilmore passed along. Jim said a barrel MUST be 21 3/4” long for optimum accuracy. That precise length, he stated, sets up a vibration pattern that duplicates well from shot to shot. Virgil faithfully followed that advice on his guns."

Edit; Posted before I read LRPFF52 above ...

Jack

[adamjp]

I settled on 21in with my Grendel boltgun simply because that balanced best in the stock, and matched the 6/223 I had built to the same pattern.

I doubt I would notice a useful velocity change if I went back to a 19in barrel.

[LR1955]

DO YOU SEE A DIFFERENCE IN PERFORMANCE FROM LET SAY .3 GR OF POWDER? You bet you do so why wouldn't you see a break-off in accuracy at a certain length/velocity. Harmonics is an important role in barrel performance and accuracy. The start of this thread was Barrel length. And yes according to that thread there was a difference in accuracy in just 1/8 of an inch.

NO, I DON'T SEE A DIFFERENCE IN PERFORMANCE FROM .3 GRAIN OF POWDER FROM A MEAN CHARGE THAT I HAVE FOUND TO BE GOOD.

If any of my barrels were that sensitive to such a minor change in conditions, I would replace them since they would have proven to be undependable.

If you are talking about bench rest guys who shoot for group at 100 or 200 yards, I am more prone to agree.

LR55