I just got my 2012 Hornady LE & Military catalog and they've included the 55gr GMX loading in their catalog. It looks the same as the superformance GMX loading. http://www.cheaperthandirt.com/72020-1.html Here are the specifics: Product # = 81255 (5.56mm pressure) 55gr GMX (no polymer tip that's typical with other GMX bullets. It resembles a non-boattail TSX but with a larger internal HP cavity) B.C. = .245 S.D. = .157 Advertised Velocity out of a 16" test barrel): Mz = 3130, 100yd = 2739, 200yd = 2380, 300yd = 2049 Gel Test: 16" 1:9 weapon Measured Velocity = 3193 21" Penetration (pretty amazing for a fully-expanded 55gr .22 cal bullet) Max Cav = 4" (not nearly as dramatic as the 75gr TAP) Depth to Max Cav = 5" Entry = 1" Retained weight = 55gr The bullet looked like a perfect mushroom. I suspect that the guilding metal construction will retain its petals through intermediate barriers better than a pure copper design . The profile of the mushroom looks more similar to a conventional bullet versus the TSX that has substantial gap between the petals. I bet this would make a good hunting round as well. By the way, the gel shot with the 75gr 5.56mm TAp 8126N still looked the most impressive of any .223/5.56mm round. It obviously remains a top pick for unobstructed shots.