More on the fast twist issue
#1
Guest
Posts: n/a
More on the fast twist issue
I read an interesting comment from doc white on the 1:28 versus 1:20 twist. Here it is:
Seems to me that it would be intuitive to know that there is no such thing as a single twist that is effective over all the ranges of bullets lengths, weights and velocities. Truth is that each bullet (of whatever length, weight and BC) has its own particular twist requirements at each velocity that it is shot at. Long term studies over the past 100 years have shown that optimum twist for really long bullets*like 460-520 gr in 450 caliber require twists of 1-18 to 1-20. I just ordered a 458 barrel*for a 45-1 7/8" cartridge (the*45-110) with a 1-18 twist. I intend to shoot 520 grain bullets with about 75-90 grains Black Powder at more or less 1200 FPS for long range cartridge. This is exactly the load I use in my muzzleloading Whitworth copy with the same bullet but a 1-20 twist, and I win 700 yard matches with it. If you want to shoot*puny pistol bullets in a 45, using sabots, like many of our modern hunters are doing, then 1-28 might be OK, 1-32 might be better, depends on the BC and the velocity of the*bullet. The BC of a .450 caliber 520 grain bullet is .36, BC of a .357caliber 158 grain saboted pistol bullet is .18 or worse, some as low as .12. Obviously, a single twist won't cut it with both bullets. Also, obviously, the bigger slower bullet with the higher BC will have far higher downrange energy, penetration and knockdown than the puny pistol bullet despite the pistol bullets flatter shorter range trajectory.*
Seems to me that it would be intuitive to know that there is no such thing as a single twist that is effective over all the ranges of bullets lengths, weights and velocities. Truth is that each bullet (of whatever length, weight and BC) has its own particular twist requirements at each velocity that it is shot at. Long term studies over the past 100 years have shown that optimum twist for really long bullets*like 460-520 gr in 450 caliber require twists of 1-18 to 1-20. I just ordered a 458 barrel*for a 45-1 7/8" cartridge (the*45-110) with a 1-18 twist. I intend to shoot 520 grain bullets with about 75-90 grains Black Powder at more or less 1200 FPS for long range cartridge. This is exactly the load I use in my muzzleloading Whitworth copy with the same bullet but a 1-20 twist, and I win 700 yard matches with it. If you want to shoot*puny pistol bullets in a 45, using sabots, like many of our modern hunters are doing, then 1-28 might be OK, 1-32 might be better, depends on the BC and the velocity of the*bullet. The BC of a .450 caliber 520 grain bullet is .36, BC of a .357caliber 158 grain saboted pistol bullet is .18 or worse, some as low as .12. Obviously, a single twist won't cut it with both bullets. Also, obviously, the bigger slower bullet with the higher BC will have far higher downrange energy, penetration and knockdown than the puny pistol bullet despite the pistol bullets flatter shorter range trajectory.*
#2
#3
Guest
Posts: n/a
Pack quite the punch on both ends of the gun
#5
Guest
Posts: n/a
Older 45 super disc 1:20, white 451 1:20 , English sporting rifle 1:20 or 1:18, Gibbs or whitworths with 1:18 . Those are the ones I would pick from to start with
#6
I had an English sporting rifle kit picked out, but after looking into it a little farther, it turns out it was designed to be "bench" rifle, with a long barrel, no ramrod, etc. If I'm going to get a gun it will be for hunting first and foremost. They said they could modify the design and add the barrel rib, ramrod, shorten the barrel, etc. but would add almost $200 to the cost and I just don't think I can swing that at this point.
#7
I shot roundball and big conical bullets for a long time. I never worried about the fact that a pistol bullet was twice as fast. When that conical got there, it knew its job. But I have to admit... sabots and pistol bullets are fun to shoot.
#9
Nontypical Buck
Join Date: Mar 2008
Posts: 1,181
With the right sights you aim right at the target no mater what the range is.
I am a big fan of big heavy bullets paper patched and sized to fit the barrel exactly the way I want it to. On my new .451 load that 409 gr bullet has over 1000 foot pounds of energy at 200 yards. I am not a big fan of shooting the first shot past 150 yards. But if I had an animal hit and wanted to put another one in him I am planning to sight the rifle in out to at least 300 yards. Ron
I am a big fan of big heavy bullets paper patched and sized to fit the barrel exactly the way I want it to. On my new .451 load that 409 gr bullet has over 1000 foot pounds of energy at 200 yards. I am not a big fan of shooting the first shot past 150 yards. But if I had an animal hit and wanted to put another one in him I am planning to sight the rifle in out to at least 300 yards. Ron