Matthew323
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I am trying to design a fairly lightweight bullet that will shoot out of a .40 caliber, Colerain, gain twist barrel with 0.012" deep, square bottom grooves. These are barrels designed to shoot patched balls well in excess of 2,000 f.p.s., but also be capable of shooting a light-for-caliber lead conical over a wool wad. The twist in a 42" long barrel starts at a 1:81" rate of twist at the breech, and quickens to a 1:36" rate of twist at the muzzle.
My question to those who have experience shooting lead bullets in .40 caliber is do you think it is possible to achieve a muzzle velocity of 1,900 f.p.s. with a 242.7 grain pure lead bullet using Swiss fffg black powder?
I used the Accurate Molds #40-265I bullet as the basis for a new design, taking the nose off of the Accurate Molds #45-459M bullet.
ogive's radius = R.5
nose's length = 0.195"
With four tapered driving bands just like a Lee R.E.A.L. bullet.
4th band's diameter = 0.418"
3rd band's diameter = 0.411"
2nd band's diameter = 0.404"
1st band's diameter = 0.397"
average band diameter = 0.4075"
Overall length = 0.735"
length, 4th band = 0.120"
length, 3rd, 2nd, 1st bands = 0.070"
length, grooves (3) = 0.050"
length, shoulders (6) = 0.010"
1. 265 grains (wheelweight metal) × 55 ÷ 53 = 275 grains (pure lead)
2. 275 ÷ 0.404" × 0.4075" = 277.38243 grains (P-L)
3. 277.38243 ÷ 0.84" (bullet's length) = 330.22 × length of any new bullet
4. 330.22 grains (P-L) × 0.735" long = 242.7117 grains (pure lead)
When I entered the data in the JBM Stability Calculator I was just spitballing with the 1,900 f.p.s. velocity estimate. It seemed ""REASONABLE"" to my demented mind after talking with Brad Emig at Cabin Creek Muzzleloading, who has built more than a couple of rifles using Colerain's .40 caliber gain twist barrels. He reported some owners pushing the 2,500 f.p.s. velocity limit with these barrels, and a patched ball. Of course, a 0.395" diameter ball only weighs about 90 grains, about 1/3 the weight of my proposed new bullet.
I am curious as to what experienced conical shooters think might be possible with one of these barrels and black powder. With flintlock ignition, of course. With percussion ignition, higher velocities could automatically be expected.
Thanks in advance for any, and all input.
Bruce
My question to those who have experience shooting lead bullets in .40 caliber is do you think it is possible to achieve a muzzle velocity of 1,900 f.p.s. with a 242.7 grain pure lead bullet using Swiss fffg black powder?
I used the Accurate Molds #40-265I bullet as the basis for a new design, taking the nose off of the Accurate Molds #45-459M bullet.
ogive's radius = R.5
nose's length = 0.195"
With four tapered driving bands just like a Lee R.E.A.L. bullet.
4th band's diameter = 0.418"
3rd band's diameter = 0.411"
2nd band's diameter = 0.404"
1st band's diameter = 0.397"
average band diameter = 0.4075"
Overall length = 0.735"
length, 4th band = 0.120"
length, 3rd, 2nd, 1st bands = 0.070"
length, grooves (3) = 0.050"
length, shoulders (6) = 0.010"
1. 265 grains (wheelweight metal) × 55 ÷ 53 = 275 grains (pure lead)
2. 275 ÷ 0.404" × 0.4075" = 277.38243 grains (P-L)
3. 277.38243 ÷ 0.84" (bullet's length) = 330.22 × length of any new bullet
4. 330.22 grains (P-L) × 0.735" long = 242.7117 grains (pure lead)
When I entered the data in the JBM Stability Calculator I was just spitballing with the 1,900 f.p.s. velocity estimate. It seemed ""REASONABLE"" to my demented mind after talking with Brad Emig at Cabin Creek Muzzleloading, who has built more than a couple of rifles using Colerain's .40 caliber gain twist barrels. He reported some owners pushing the 2,500 f.p.s. velocity limit with these barrels, and a patched ball. Of course, a 0.395" diameter ball only weighs about 90 grains, about 1/3 the weight of my proposed new bullet.
I am curious as to what experienced conical shooters think might be possible with one of these barrels and black powder. With flintlock ignition, of course. With percussion ignition, higher velocities could automatically be expected.
Thanks in advance for any, and all input.
Bruce
