1-10 or 1-12 twist for 308W Garand build

[lancem]

Title says it all pretty much. I'm building another M1 and making it 308. I can get either 1-10 or 1-12 twist barrels, which would be the better choice for shooting cast? I'm thinking of using 311299 as that's what I use with good success in my '06 Garands.

[Ford SD]

Title says it all pretty much. I'm building another M1 and making it 308. I can get either 1-10 or 1-12 twist barrels, which would be the better choice for shooting cast? I'm thinking of using 311299 as that's what I use with good success in my '06 Garands.


For cast the 1/12 will be better unless you can find a 1/14

1/12 will give you better Velocity before accuracy drops off

[country gent]

Next is 4 or 6 grooves both are available in the M1 countour.

[Char-Gar]

Oh yes, 1-12 for sure.

[LuckyDog]

Next is 4 or 6 grooves both are available in the M1 countour.

Wellllll?

Are you gonna leave me hanging on this?:confused:

I'll guess six groove. More bites into the lead is better?

Enquiring Minds want to know?

[lancem]

I know Wilson makes a 1-12 four grove, who makes a 6?

I'm with LuckyDog wondering which is better, 4 or 6, and why?

Thanks for the replies!

[Scharfschuetze]

I'm sure that the number of grooves equals "six of one and a half a dozen of the other." Match shooters have argued the point ad nauseam, yet the best shooters all have rifles with a different numbers of lands and grooves on their favorite rifles. The really important measurement is how uniform the bore diameter is from throat to muzzle. As noted by posters above, the 1 in 12 twist will be better than the 1 in 10 twist for cast boolits.

[Larry Gibson]

The 12" twist will be the best for cast bullets and will also provide as good accuracy as possible with your M1 with jacketed bullets. It will fully stabilize jacketed bullets up to 185 gr for as long range shooting as you want to do with all "M1" loads. It also will stabilize the 311299 down to a velocity where the action will not function at all. The 12" twist will allow a higher velocity with that 311299 bullet while maintaining accuracy than you would get with the 10" twist.

Larry Gibson

[country gent]

Douglas made service rifle countours in 4 and 6 groove configuration for years. I have a 4 groove 308 med heavy on a garand in 1-10 twist carbon steel thats was a tack driver for many years with jacketed bullets never tried cast in it. The argument was 6 grooves gave less distortion to a bullet and 4 grooves supposedly had a longer life. Boots Obermeyer made a very accurate 5 groove barrel with a special form he called 5 R ( I think Krieger is making it now). Pac nor and Lilja do a 3 groove barrel also, the theroy is they center the bullet better in the bore. I believe after twist rate the next important thing is how accuratly the chamber is reamed on center and straight with bore then how well the throat matches to the groove bore dias. But had to ask which you were considering.