What rifle at what range? A M4 has the gas port closer to the chamber. A full power round will batter the gun.
For CQB, accuracy is not an issue, so use just enough to cycle the gun properly. Extra recoil does not help.
The Op said a keltec su16. He is probably asking because unlike most powders, there is hardly any reload data out there for wc735 other than "5% faster than h335".



























