Hard to say. In general, the shorter the bullet, the better it is stabilized by a given twist rate. An interesting example is the .32 HBWC. A test done with commercial loads of .32 S&W Long WC ammo (the International centerfire pistol standard round) found that faster twist than the standard 18 3/4" did better. Groups got tighter until about 12" twist, then they opened back up again when faster than that. You'd think the extra spin would throw the skirt out centrifugally, and the traditional spin shows being good enough on a twist calculator, but, the long bullet may need long range to go to sleep with the traditional twist rate, and the 12" would certainly make that happen a lot sooner.
All I can think with the Berry's, assuming their tests are valid, is that the greater bearing surface lets the bullet straighten itself better in the bore and perhaps even just tip less in a case when loaded? I know I have never been able to get 185 grain .45's to shoot quite as precisely as 200 grain bullets do. The little high speed 155 grain bullets I tried once proved impossible to get good grouping with. So, something's going on with short bearing surface. At least, I think that's what it is.
Rocca2506,
Check your range rules. Berry's bullets are plated, not jacketed, like commercial cartridges use. I assume airborne lead is their concern, and Berry's should be fine for that, but if they have some other reason the difference might matter to them.
In general, also note that plated bullets use lead bullet loads and not jacketed bullet loads. The plated copper is a good bit softer than the gilding metal jackets are made from, and they upset more easily at high pressure, which can cause the pressure of maximum jacketed bullet powder charges to go even higher and become excessive in some guns.
All I can think with the Berry's, assuming their tests are valid, is that the greater bearing surface lets the bullet straighten itself better in the bore and perhaps even just tip less in a case when loaded? I know I have never been able to get 185 grain .45's to shoot quite as precisely as 200 grain bullets do. The little high speed 155 grain bullets I tried once proved impossible to get good grouping with. So, something's going on with short bearing surface. At least, I think that's what it is.
Rocca2506,
Check your range rules. Berry's bullets are plated, not jacketed, like commercial cartridges use. I assume airborne lead is their concern, and Berry's should be fine for that, but if they have some other reason the difference might matter to them.
In general, also note that plated bullets use lead bullet loads and not jacketed bullet loads. The plated copper is a good bit softer than the gilding metal jackets are made from, and they upset more easily at high pressure, which can cause the pressure of maximum jacketed bullet powder charges to go even higher and become excessive in some guns.
