This is the 170 grain MiHec 359 Hammer bullet, which is basically a wide flat nose design with a big grease groove and a gas check. Bullet is also in hollow point. This test is with the flat nose pin inserted.
Alloy is 91pb-6sn-3sb, an alloy I prefer. I suspect the high tin/low antimony content is key to the excellent weight retention.
Gel is 9:2 water to unflavored gelatin (by VOLUME) calibrated bare with a 17 caliber steel bb shot at 580 FPS which penetrated 3.5" This is within FBI spec (which is based on pork). 4 layers of lightweight denim was used in front of gelatin (if somebody can give me some hair-on buckskin I will use that instead).
Rifle is Remlin 1894c 357 Magnum Carbine with 18" barrel. Velocity is 1800 FPS with 17 grains of 300MP using this bullet with no pressure signs. This should be just under 35kPSI MAP. Lubricant is Carnuba Blue. Gas check Hornady.
Penetration 16". Expansion 0.68" Weight retention 99%+.
This to me proves my theory that if the velocity is adequate, and the alloy appropriate, hollowpoint bullets are not necessary for excellent expansion.