Green mountain barrel made before 1993

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I have a .50 caliber green mountain barrel that's unfired. I called the company and gave them the serial number to confirm what the twist rate is and they said it was made before 1993 and it's most likely 1:70 twist. I used to have a Renegade with 1:66 twist and it shot round ball very well so I'm guessing since 1:70 is even slower is should shoot roundball even better? Might go shoot it today and break it in/fire lap the barrel.
 
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The quickest way to break in a new barrel, particularly a GM, is to run a small square of red Scotch bright pad down the bore to take off the sharp corners of the lands and polish the inside of barrel. You will need a smaller cleaning jag to accomplish this, perhaps a .45 or even a .40. GM barrels are rough on the inside.

Here is how to do it.

 
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The quickest way to break in a new barrel, particularly a GM, is to run a small square of red Scotch bright pad down the bore to take off the sharp corners of the lands and polish the inside of barrel. You will need a smaller cleaning jag to accomplish this, perhaps a .45 or even a .40. GM barrels are rough on the inside.

Here is how to do it.


Interesting. When I get the chance to shoot my GM barrel I'll have to determine if using the scotch bright pad is needed. Since it's unfired I'm sure it will be loading pretty tight. Hopefully that barrel will last me a lifetime once I get it broken in.
 
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I have a .50 caliber green mountain barrel that's unfired. I called the company and gave them the serial number to confirm what the twist rate is and they said it was made before 1993 and it's most likely 1:70 twist. I used to have a Renegade with 1:66 twist and it shot round ball very well so I'm guessing since 1:70 is even slower is should shoot roundball even better? Might go shoot it today and break it in/fire lap the barrel.
If it’s a better shooter than the 1:66 it won’t be because the twist rate is slightly slower. It will be because of other, quite probably unexplained or unexpected factors. We’re using technology that is hundreds of years old and we think it’s all explainable or quantifiable but it’s not. Every rifle is a law unto itself. Shoot the gun. A lot. Experiment with loads and components of loads, one change at a time, methodically. Take notes. There’s where you’ll find the best accuracy.
 

alcessapiens

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I have a GM barrel on my left hand Tennessee mountain rife (flintlock with primitive sights) it’s absolutely superb. I lapped it very slightly when new as it cut patches. Fire yours and retrieve the patch, if it’s intact keep right on shooting.
 

alcessapiens

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Mine shot well but cut the patches. Very light lapping and it was fine. I was shooting a fairly tight ball/patch which likely contributed to the problem.
 

M. De Land

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I have a .50 caliber green mountain barrel that's unfired. I called the company and gave them the serial number to confirm what the twist rate is and they said it was made before 1993 and it's most likely 1:70 twist. I used to have a Renegade with 1:66 twist and it shot round ball very well so I'm guessing since 1:70 is even slower is should shoot roundball even better? Might go shoot it today and break it in/fire lap the barrel.
Load and clean with a muzzle protector of some kind and it will last a couple of life times.
 

bang

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I picked up one on a prize blanket. About floored me when I saw the marking. Shoots very good. I use it at my club's monthly meeting and shoot.
I put a Mowrey barrel on a Renegade stock that's going to be a nail driver. First fives shots hit 2 inch targets at 25 yards.
You got a good one.
 

Dude

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Here's Lee Shaver's break-in method:

 

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