2-groove barrel - originally shallow rifling?


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desidog
May 10, 2011, 12:51 PM
I recently acquired a Remington '03A3, and I need some schooling on two groove barrels.

The barrel is dated 10-43, and the bore mic's at right around .299; which i would think has plenty of life left in it (same .299 diameter as one of my 300wsm's with 200 rds through it); but when i was looking down the barrel at the lands and grooves, there is far less contrast between lands and grooves than on any of my other rifles.

When I inserted a cartridge into the muzzle, there was about 1/8" between the crown and the casing...obviously not brand new, but not shot-out either, i imagine.

So i know that two groove barrels were made in wartime to expedite the process, did they also not rifle as deep?

Or is it time for a new barrel on this beast? I'll do some test-driving this weekend no doubt, and find the accuracy first hand, but in the mean time, any information would be appreciated.

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VA27
May 10, 2011, 03:08 PM
Nothing wrong with a 2-grove barrel. They even used 'em on the 03A4 Sniper rifle. I would imagine that the 'low contrast' is because the groves are so narrow and the lands are so wide. As long as the crown is good, I think you'll be pleased with the accuracy.

SlamFire1
May 10, 2011, 04:15 PM
recently acquired a Remington '03A3, and I need some schooling on two groove barrels.

The barrel is dated 10-43, and the bore mic's at right around .299; which i would think has plenty of life left in it (same .299 diameter as one of my 300wsm's with 200 rds through it); but when i was looking down the barrel at the lands and grooves, there is far less contrast between lands and grooves than on any of my other rifles.

If the groove depth gives you .308 then you are good to go.

When I inserted a cartridge into the muzzle, there was about 1/8" between the crown and the casing...obviously not brand new, but not shot-out either, i imagine.

Check it with a muzzle erosion gage, you can get those from the CMP, but it does not sound as worn out.

So i know that two groove barrels were made in wartime to expedite the process, did they also not rifle as deep?

The grooves were as deep. All they did was to eliminate two cutting sides from the broach. If they had added those sides it would have been a four groove.

Or is it time for a new barrel on this beast? I'll do some test-driving this weekend no doubt, and find the accuracy first hand, but in the mean time, any information would be appreciated.

Shoot it but if your accuracy is awful, first bed the action. The rear tang on the 03 actions is small and compresses the wood in the stock. I have not yet seen a 03 or A3 in its original stock were the barrel was not touching the top of the upper band due to wood compression at the rear tang. When that happens the action is bowed.

rcmodel
May 10, 2011, 05:02 PM
When I inserted a cartridge into the muzzle, there was about 1/8" between the crown and the casing...That doesn't tell you anything.
Almost all 30-06 bullet ogives begin to taper towaard the tip as soon as they come out of the case mouth. And different bullet weights and brands are different.

You would have to have a loose bullet without a case to get too the full .308" dia shank part of it.

rc

desidog
May 10, 2011, 06:03 PM
Thanks for the replies.

The crown looks good.

I do need a CMP gauge; my current tools for this job consist of Go/NoGo and a micrometer.

RC, you bring up an interesting point that i was thinking about while checking out the gun...i also tried a 308 DAG round, and had different results than with the 30'06...Federal, i think. To have a "control" in the experiment, i also inserted both those cartridges into my M70 and M99 .300wsm's...my other .308s have muzzle devices....the rounds went farther in than the other guns, but not much farther to cause me concern. The variation was consistent; and it mic'd well enough, but that rifling does look weak.

Slamfire1, thanks for the responses. I was not aware of looking at bowing in the action.

Also, what have you guys found with handguard tension vs/ accuracy? I searched it a bit this afternoon, but have found too many varying opinions. That's another thing i'm looking forward to tweeking at the range to see the variation!

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