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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Hitting Right On With The First Shot And Barrel Preparation.
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<blockquote data-quote="Guest" data-source="post: 26998"><p>Wyo... I think the answer varies with the caliber, twist rate, bore finish, pressure, bullet construction, and heat. </p><p> </p><p>You bet I have data on this one. We have analyzed it from a couple of different angles. The first way we looked at it was objective precision on the target. If your objective is to maintain better than .3 MOA with a PPC, you can fire over 30 rounds before accuracy starts to degrade outside your limits, some coated bullets could go over 50 shots. This is a small case with a relatively slow twist.</p><p> </p><p>The other angle we approached this at, was from the long range shooters perspective. Take a big 30 cal like your RUM (we used a Wolf) Shoot it over your chrono and determine the std. dev. of velocity. Now continue your shot string, allowing the barrel to cool between shots. You will reach a point where the gun will shoot consecutive shots that are HIGHER than your mean velocity. There is some dispute by statisticions as to how many shots need to be consecutively above the mean to be significant. The SPC boys claim that 7 in a row is reliable indication that something has fundamentally changed, I tend to agree with this. With the Wolf, about the 18th to 22cnd shot we start to see a slow climb in velocity as the barrel continues to foul with full pressure loads.</p><p> </p><p>Two things seem to cause the increase in velocity, the fouling in the throat, and the copper building up on the vertical wall of the lands on the side that takes the load for spinning the bullet up to RPM.</p><p> </p><p>BOTTOM LINE:</p><p> </p><p>With the big gun, I would clean every 12 to 15 shots. With the smaller stuff I would let the gun tell me when to clean.</p></blockquote><p></p>
[QUOTE="Guest, post: 26998"] Wyo... I think the answer varies with the caliber, twist rate, bore finish, pressure, bullet construction, and heat. You bet I have data on this one. We have analyzed it from a couple of different angles. The first way we looked at it was objective precision on the target. If your objective is to maintain better than .3 MOA with a PPC, you can fire over 30 rounds before accuracy starts to degrade outside your limits, some coated bullets could go over 50 shots. This is a small case with a relatively slow twist. The other angle we approached this at, was from the long range shooters perspective. Take a big 30 cal like your RUM (we used a Wolf) Shoot it over your chrono and determine the std. dev. of velocity. Now continue your shot string, allowing the barrel to cool between shots. You will reach a point where the gun will shoot consecutive shots that are HIGHER than your mean velocity. There is some dispute by statisticions as to how many shots need to be consecutively above the mean to be significant. The SPC boys claim that 7 in a row is reliable indication that something has fundamentally changed, I tend to agree with this. With the Wolf, about the 18th to 22cnd shot we start to see a slow climb in velocity as the barrel continues to foul with full pressure loads. Two things seem to cause the increase in velocity, the fouling in the throat, and the copper building up on the vertical wall of the lands on the side that takes the load for spinning the bullet up to RPM. BOTTOM LINE: With the big gun, I would clean every 12 to 15 shots. With the smaller stuff I would let the gun tell me when to clean. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Hitting Right On With The First Shot And Barrel Preparation.
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