Am still guessing MRP and 22 are the same powder, due both to my results and published data. A good example is comparing Norma's data for the .270 Winchester for MRP and 130- and 150-grain Nosler Partitions, with Nosler's data using RL-22. (Alliant's on-line data doesn't list RL-22 with 130 Partitions in the .270.) The maximum powder charges are both within .2 grains, and the velocities are very similar too, certainly within lot-to-lot variations and differences in test barrels.
Yeah, whatever physical & appearance differences I've seen have not seemed to matter & like you, I just used them interchangeably over the years, mainly in 270's & 280's of which I have multiples in each caliber, & also in several 7 Mags & 338 Mags.
I always end up with the virtually same velocities from both & the same max loads in a given gun.
So, I dunno if they are different or not, & it really doesn't matter anymore, but as I said in the earlier post, the performance is the same & I've tested them both enough to feel OK using the same charges of either so I treat them as if they are the same. I've never seen any real spikes in the lots I've used either. I've always bought quite a bit at one time, so my number of lots vs the amount used is probably lower than many others.
And that encompasses RL-22 from when it 1st came out & MRP for the same rough time period up until now.....so for me, that time period would have started in the late 88-'89 until now. I have both powders in their old packaging, & both powders in their new packaging. I cannot recall what year MRP was introduced but I think it was in the mid-70's; RL-22 & 19 were introduced in 1988 & I stared using them all around that time.
MM
