These Hornady SX bullets (and the Sierra Blitz (NOT BlitzKing)), are so fragile that you have to be careful what you shoot them in.
These two bullets are pretty much similar - they both have 0.009" thick jackets, whereas normal varmint bullets have 0.018" to 0.02" jackets, so the jackets are 1/2 the thickness on normal varmint bullets.
If you drive them (the .224" ones) past 3450 in a 14" twist, you are at the ragged edge of them coming apart.
I just recently tested loads with them from a .223, and at 3400, they were fine, at 3450, you could see little black tails at the edge of the bullet holes at 100yds, where the jacket was starting to fail because of centrifugal forces... at 3500, they will often come apart before they hit the target.
I have been using these bullets since the 70's (the "blitz" too), and I have found that 3400 fps is the highest speed that they are 100% reliable - over that, it is shakie.
In a 14" twist, 3400 fps translates to about 174,850 RPM.
If we use that as an upper limit of evolutions per minute, a little math tells that with the following twists, the top muzzle velocity is limited to:
14" = 3400 fps
12" = 2915 fps
10" = 2430 fps
9" = 2190 fps
7" = 1705 fps
So you can see why guys with AR-15s and/or fast twist barrels, or guys that try these bullets in .22-250s and .220 Swifts are NOT happy.
These bullets are ideal for rifles in the .222/224/222 Mag family with 14" twists, and the .221 Fireball (with 14" or 12" twists).
I shoot these in several benchrest grade rifles, and they can put five in one raggity hole.
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