Twist rate conflicted

[TheOTHERmaninblack]

Hi, I've been lurking a bit since being referred here by the Grendel faq over on ARFcom. I made my decision to go 6.5 a couple of years ago, but money concerns stopped my plans. Now, however, I have bitten the bullet, sold my G3, and am in the procurement stage of my grendel.

Almost instantly, I've run into a quandry. Satern has some button barrels in my price range, deeply fluted and purty, but the listed twist rate is 1:8. AA has button barrels with lesser fluting, and only at the rear, for about the same price, with a twist of 1:8.75.

This is going to be my primary go-to rifle for all ranges. I've about decided that 18" should do what I need, though I keep waffling between it and 20" But the main question is whether that 1:8 twist is fast enough for the cartridge to fly true. I'll go with the less pretty barrel if it works better, and most everything I've read about the 6.5 is that it wants 8.5 or better twist.

Thanks,
TOMIB

[bwaites]

Either rate will stabilize any bullet you want to shoot in the Grendel just fine.

Satern makes cut rifled barrels, so my guess is those are Liberty barrels. AA's could be any of several different companies.

[TheOTHERmaninblack]

Yep, the Liberty barrels. In going back to the AA site, I noticed that some of their button barrels were also 1:8, so I guess I'm going with the Liberty unless anybody here has better advice?

Will there be an issue using reformed 7.62X39 brass with these barrels, which I'm thinking are using the AA bolt?

[Whelenon]

From what I've read the 1-8 is better for the heavier bullets and 1-9 is best for the lighter bullets. But this is theory how it actually works at the range could be a whole different thing. Anyone have any shooting experience with the different twist?

[Hoot]

I read that you have to factor in the barrel length as well. What is OK for a 24" barrel may be a little too slow for an 18" barrel for the same bullet weight.

Hoot

[RangerRick]

Yep, the Liberty barrels. In going back to the AA site, I noticed that some of their button barrels were also 1:8, so I guess I'm going with the Liberty unless anybody here has better advice?

Will there be an issue using reformed 7.62X39 brass with these barrels, which I'm thinking are using the AA bolt?

Fire formed brass will work fine. The case capacity is a little less, so pressure will be a little higher with the same powder charge as Grendel brass. Since you can't get as much powder in, the top end muzzle velocity may be a little lower.

Since the Grendel is an intermediate cartridge, the mv is on the low side to begin with, so you might want to get as much barrel as is practical for your use. If you are going to tote it around the weight and length become a factor. Also, the balance can get out of whack with a long barrel, so that's a consideration.

[TheOTHERmaninblack]

Ordered my Liberty barrel with an extra bolt today. After a couple of years of screwing around, I'm finally off to the races!

[WillD]

Here's the formula I've always used:

Bullet Length/Caliber Diameter= Nominal Caliber
150/Nominal Caliber= X2
X2 x Caliber Diameter= Twist

Lapua 123 = 1.30"

1.30/.264=4.924
150/4.924=30.463
30.463x.264=8.042 Twist rate

-Will-

[MikeinGa]

Here's the formula I've always used:

Bullet Length/Caliber Diameter= Nominal Caliber
150/Nominal Caliber= X2
X2 x Caliber Diameter= Twist

Lapua 123 = 1.30"

1.30/.264=4.924
150/4.924=30.463
30.463x.264=8.042 Twist rate

-Will-

That look right. My 123 A-max is: 1 in 8.7 that's using my Lee Shooters program and they call it minimum twist. I checked my 24 inch barrel and it's 1 in 8.5 twist. That shoots a 1/2 MOA.

Mike