I used to have a 1917 Enfield in .335 B/W with an 18" barrel on it. I got 2450 out of 250 gr. bullets, and nearly lost my eyebrows from muzzle flash with each shot (I used H380). It was accurate. I loaded some 225s and got about 2600 from it, with slightly less accuracy. I'd stick with the standard whelen if you have a 'normal' length barrel.