nakneker
Gold $$ Contributor
3 twist, never heard of such a thing - I’ll have to read up.The 243 necked down to 224 has been done since the beginning of time...well since Winchester brought it out in 243 ...same for the 6mm Remington necked down and both Ackley improved...Sierra had loading data for 22- 6mm Ackley 20 yrs ago in their manual, faster twist for long bullets of the time...really old, 224 Middlestadt was one of the old ones, along with 224 cheetah Jim Carmichael...nothing new.
RPM, some hold together at 400,000 rpm some don't.
17 Rem 4900 fps 9 twist 15.5 all copper no problem 392,000 rpm 58 gr Vmax 4100 fps 7 .5 393,600 rpm twist no problem.
The 3 twist in the 8.6 Blackout is a problem...285 eld don't make it to 50 yds at 1450 fps, 348000 rpm, failed...disappointed in that big heavy target bullet. It must have a thin jacket. A few leads bullets will make 50 yds at 1600 fps inching up to 400,000 rpm The 225gr interlock will blow up inside tbe muzzle brake, as soon as it leaves the confines of the 3 twist barrel, at 2100 fps, 504,000 rpm.
All copper bullet appears to be required much above 1200 fps for certain arrival to the target...will try them soon, to see if they can handle 504,000 rpm. This is a subsonic only or slightly above caliber for most lead bullets.