Just picked the pistol up from Gunrunners this morning After reading the MkIV thread on red dots I decided to go with the venom. Going to be shooting steel with it so I figured the six MOA would be faster. First time with a red dot on my pistol and my question is where on the rail should I mount the optic? Front, middle or back? I've tried all here on my workbench and it doesn't seem that different to me. Is there a difference?