Kirby, Can you recall what velocity the Wildcat 107 grain ULD achieved before it came apart in your .224 AM.
Last weekend I tried the 100 grain WC in my 224 Clark (Krieger 26 inch 6.5 twist) again, and worked up from 47.0 to 55.0 grains of H870 which appeared to be maximum. However, my CED chronograph
did not work again for the second time in succession, so I do not have any velocities to report.
A keyhole appeared on the target at 50 grains, and beyond that only bullet fragments reached the target, which was a repeat of the previous test.
I estimate that the 50.0 grains/H870 load was producing about 2800 fps, but hopefully I can get my chronograph to work next time around to verify this.
I have also been trying some bullets made by a local bullet maker in Oz. The 105 grain HPBT (1.305 inches, 10 ogive Sierra MK profile) was built on the J4 jacket and somewhat predictably suffered a similar fate to the 100 grain WC. The 105 Little even came apart when I was fireforming cases.(39.0 grains IMR 7828)
After the original failure of the 105 HPBT, Gary Little subsequently made up a 105 and 110 grain FBHP (6 ogive) using 277 cal jackets drawn down progressively to .224. I worked up from 49 to 52.0 grains of H870, and these bullets held together at each loading.
He also made up a 104 grain FBHP built using a .257 cal jacket (6 ogive), which again held together at the only load fired. (52.0/H870)
Gary also made up a 85 grain FBHP and 85 grain HPBT,(10 ogive using a 257 cal jacket) where the lead core was melted in the jacket. (very time consuming)
I worked up from 55 to 57 grains H870 with both 85 grain bullets, and have had no failures on both test days, and accuracy appeared to be good with several sub 0.5 moa groups. Hopefully on the next outing I can get that chrono to work and get some data.
Gary rang today to tell me that he is sending me some 100 grain HPBT's (10 ogive) that were made using a .257 cal jacket, and using the same bonding process as used in the 85 grain bullets.
Last weekend, out of curiosity I also tested the Sierra 80 grain MK, and worked up from 55.0 to 59.0 grains H870. The 58.0 grain load produced a massive black comet tail on the target, but surprisingly all the other loads produced round holes on the target.
The other positive to come out of last weekends testing was with my 257W. (Krieger 7 twist). After the previous success with the 156 grain WC and the failure of the 142 grain WC ULD, I tested the 125 grain Wildcat ULD, and the Nosler 100 and 115 grain BT's.
I worked up from 72.0 to 76.0 grains AR 2218 (H50BMG in US) with the 125 WC. Excellent accuracy (.265 & .335 moa) was achieved with the 73.0 and 74 grain loads, and maximum pressure appeared to be reached with the 75.0 grain load. I subsequently decided to fire the 76.0 grain load and the 3rd shot keyholed into the target. (maybe caused by barrel fouling, as 18th shot after cleaning)
I worked up from 75.0 to 79.0 grains AR 2218 with the Nosler 115 BT and had no failures, with 2 groups producing sub 0.5 accuracy. The 78.0 grain load may be the maximum, as the 79.0 grain load produced slightly stiffer extraction.
I worked up from 76.0 to 81.0 grains H870 in the Nosler 100 BT and again had no failures, which surprised me as at an estimated 3,600+ fps, this bullet is producing 370,000 rpm in my 7 twist barrel. The real positive from this, is that the flexibility of the rifle has increased substantially, with a bullet range of 100 - 156 grains.
Hope I haven't bored you and that the above is of some interest. Brian.