Originally Posted by DWalt

A little off topic, but I once did some extensive testing of LRM vs. LR primers (CCI) using a slow propellant (I think it was Norma 205) in .270 Win with 130 gr bullets. Results were that both loads worked equally well, with near-identical average MVs. But grouping appeared slightly better using regular LR primers which may or may not be significant. Usual advice is that the .270 loaded with slow powders requires LRM primers. I did not find that to be the case, except maybe it might be true under some special circumstances, such as in very cold temperature environments.