Thought I would add my experience with some of these bullets mentioned in 10mm.
Not all FMJ bullets are created equal. I tested some boutique commercial 180 gr fmj's a couple of years ago against some 200 fn hardcast that I had loaded myself. The 180's are advertised as "woods defense rounds" including for black bear.
The test medium I used was freshly killed cow elk skulls lined up. The 180 gr "woods defense" load was determined to have a thin brittle jacket, and brittle lead core, with the bullet breaking up on the first skull and shallow penetration. The 200 grain hard cast was vastly superior in penetration through the hard bone of the skulls. Absolutely no contest. Mackay's 10mm loads are similar in appearance and fps as mine and should work about the same.
The 10mm 200 grain xtp has a lower velocity range listed by Hornady than its 10mm 180 grain. This indicates to me the 200 gr is built softer than the 180, perhaps to compensate for the difference in velocity? I dunno. I do have some 200 xtp's loaded up but no 180 xtp's to test.
I hope this helps a bit.
Manny
