4 or 6 groove Garand Barrel?

[mtgrs737]

I may need to buy a new barrel for my Garand project rifle and was wondering if a 4 or 6 groove barrel would be best. I plan on shooting both J-word and cast in it. Or does is matter how many grooves?

[DaveInFloweryBranchGA]

I would think twist rate would be more important than the number of grooves, depending on what bullet weight range you want to use and what ranges you want to shoot at. Two common twists are the original 1:10 twist and 1:12. I haven't researched it in many years, but you can google twist rate effects and bullet weights. Here's a couple good links that explain the twist rate very well:

http://www.snipercountry.com/hottips/TwistRate.htm

http://www.gunnersden.com/index.htm.rifle-barrel-twist-rates.html

I have a Korean War time frame built Garand with it's well-worn original barrel. The rifle has been tuned by Hook Boutin (You can google this fella.) and he refused to remove the original barrel, saying the chamber was too good and it would be better for me to shoot the last good out of the barrel. The rifle will shoot MOA with 168 or 175 grain competition J-words if I do my part. The barrel is a !:10 twist, four groove barrel. I suspect new manufactured barrels from the quality manufacturing companies of today could match or beat it.

Regards,

Dave

[zomby woof]

Most replacement Garand barrels are 1in10. The 1/10 barrel is meant for 175 grain Plus (or there about) bullet. The 1/12 around 168 and the 1/14 around 150. The number of grooves shouldn't matter. I have a two groove on my 1903 and it shoots great. The quality of the barrel, the bullet and the careful fitting of parts on your M1 is what will make it shoot. Just my opinion.

[SierraWhiskeyMC]

The longer the projectile for a given bore diameter, velocity and air density, the faster you need to spin it to stabilize it.

I'd been erroneously posting that my 03A3 had a 1:12 barrel, but it's actually 1:10. I finally realized I misunderstood something my Dad told me long ago. While they were testing M1903 rifles during production, they suddenly found a batch that were unusually accurate, and they investigated why this was so. It turned out that the machine performing the rifling had been incorrectly set to produce rifling of 1:11-1/2" instead of 1:10. They changed it back to 1:10!

While this sounds crazy to "accuracy fiends", the reason was that while the 1:11-1/2 barrel was accurate under moderate weather conditions, in cold weather the increased air density would cause the bullet to become unstable.

Hatcher's Notebook indicates that during WWI, our servicemen were dismayed at the loss in range when they went from the Vickers machine guns to the Brownings; the Europeans were using boat-tail bullets that had much greater range than the 150gr flat-based bullets the new Brownings were using. A while after WWI ended, a 172gr boat-tail bullet was adopted, but by the time WWII came around, they were back to using 152gr flat-base spire points for both M2 ball and AP ammo. Maximum range was reduced from 3.2 miles to 2 miles, but the flat-base bullets would stay stabilized in the cold weather.


The number of grooves shouldn't matter. I have a two groove on my 1903 and it shoots great. The quality of the barrel, the bullet and the careful fitting of parts on your M1 is what will make it shoot. Just my opinion.

One would have to be a mighty good shooter with mighty good ammo in order to tell the difference between the 2-groove and 4-groove barrel.

[madsenshooter]

Haven't looked at their site lately, but Champion's Choice used to offer Garand barrels with 1 in 10, 1 in 12, and for those who couldn't decide between the two, 1 in 11. I believe they were Douglas barrels, now I gotta go look. No such selection anymore, 1 in 10, 308 or 30-06, 4 groove or 6 groove. I would think that for shooting cast you'd want the lands to be as tall as possible, the more grooves you have, the shallower the lands I believe. While we're on the subject of Garands, might as well put up a pic or two of my ratty old $185 shooter. The DCM was very good to me back in the late 80s, except the stock was so worn the receiver overhung at the rear, thus this Fajen. I don't think you're likely to find a price lower than CMP's price on the Criterion barrel. https://estore.odcmp.com/store/catalog/catalog.aspx?pg=product&ID=065CRI/M1&item=&sfv=&cat=BAR&desc=&udc=&mct=&vndr=&ba=&pmin=&pmax=&note1=&note2=&note3=&note4=&note5=&max=

[MtGun44]

No.

Bill

[c3d4b2]

Either a 4 grove or 6 grove barrel will work fine. Boots Obermeyer suggests 5R grove barrels have benefits.

http://obermeyerbarrels.com/faq.html

What does it mean when a barrel is said to be a "5R"?

5R is the form of rifling I developed for use in most target barrels and in many sporting barrels.
These barrels have 5 grooves, and the lands have angular sides. I have observed that bullet jackets
will deform such that they remain closer to the R-form lands than they will to the sharp-edged
lands present in conventional-style rifling. This reduces powder fouling at the corners of the
grooves. The angled form of the lands also helps to reduce jacket failures in quick-twist barrels.

(Note: There are other barrel manufactures making 5 groove barrels now.)

[madsenshooter]

Thanks, I never took the time to look this up and I have this heavy 6mm Obermeyer that I scored off gunbroker for $10 that has this type of rifling. It was used but has a lot of use left in it once rechambered to a longer cartridge. I have dies and a reamer for 6mm.30-40 Ackley Improved, so that's what it'll become someday.