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Lands and grooves

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Joined
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I have a Invest arms .45 cal rifle with 12 lands and grooves. I have never fired this rifle. Are there advantages of more or less when it comes to lands and grooves?
 
How deep are the grooves?

What's the rate of twist?

There's no real advantage or disadvantage other than more places for fouling to get caught, so wiping between shots is highly recommended.

You may have some trouble finding a patch ball and charge combination to take advantage of all those lands and grooves to impart spin to your ball. Or this may be intended to be a slug or minie ball gun.
 
You mentioned twist rate.
How can this be measured?
I know that this is often published information on new equipment, but how can one measure this at home?
 
Don't know about any pros or cons of a ML rifle with 12 lands and grooves, but I've noticed something interesting in a rimfire .22. When shooting the same ammo from a .22 lever-action Marlin with a 12-groove Micro-Grooveâ„¢ barrel, a Ruger bolt-action and a semi-automatic Mossberg, both with standard rifling, the Micro-Grooveâ„¢ barrel consistently shoots 100 fps slower.

Barrel lengths are all about the same. I suppose the different types of receiver could be a factor, but I suspect the decreased velocity is because of the increased friction. That matters not at all in a ML, of course, just something curious I've noticed.

Spence
 
I have seen several Spanish and Italian production target pistols with such a high number of grooves and lands, but no rifles.
 
contrarian said:
You mentioned twist rate.
How can this be measured?
I know that this is often published information on new equipment, but how can one measure this at home?
Mount a cleaning jag on a cleaning rod or your ramrod and lightly oil a clean patch.

Shove the patched jag down to the bottom of the barrel bore.

Now, wrap a piece of masking, painting or Magic tape around the exposed rod so it is flush with the muzzle.

Using a pen or marker, make a line on the tape that is lined up with the front sight.

Slowly and carefully, pull the rod back out of the bore taking special care to allow the rod to rotate freely while the patch follows the rifling grooves.

If your doing this right, you will see the mark on the tape rotate so it is no longer aligned with the front sight.

Continue to pull the rotating rod out until the mark on the tape is directly opposite the front sight. In other words, the rod has rotated 1/2 of a full turn. Then stop moving the rod.

Get a tape measure and measure the distance from the muzzle of the barrel to the lower (closest) edge of the tape.

Multiply this distance times 2. That will give you the rate of twist for your barrel.

Often when doing this, the patch will jump a groove as you pull the patched jag up the barrel so, repeat this proceedure several times, recording the distance from the muzzle to the tape.

Take an average of the distances or better yet, use the distance that was most often seen, multiply it times 2 and call it good. :grin:
 
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