I reloaded some and trimmed my cases to standard max length. The rounds cycled fine through my '57 336 and my new 336SDG. The shot very accurately in the SDG but only so so in the older gun. Both are Micro-Groove rifling, but the older 336 has more/smaller lands and grooves. I am a fan of the FTX bullets. My handloads with them have also been accurate in my Marlin 35 Rem., Custom barrelled .357 Mag T/C Contender Carbine and my Ruger 77/44 Carbine.