After 15-20 rounds consecutively with my 338 and my groups aren't as tight as they used to be either. 308 for plinking, 338 for 15 rounds at my leisure, giving my shoulder a rest. Eliminate the flinching by putting that beast in a gun vise like the lead sled or something. At least eliminate the flinch. I've shot my 338LM a bunch and it's still hard not anticipating that mule raring back to kick you in the shoulder when you squeeze that trigger.