I don,t think RL22 and MRP are the same. If I make to loads just the same RL2 will be faster, but I will have to stop adding powder to
the RL22 load as it gets over pressure. With the MRP after I get about one more grain of powder it starts to exceed velocity of RL22,
and I can keep going a little. Also I get more velocity from heavy bullets in the 270 win. Have started to use a lot of RL23 in the 270 with 140gr
bullets, also works good in 270 WSM. But not so good in small case, you can not get enough in.
This has been true for me as well and some burn rate charts show MRP as slightly slower. than R22 What I have read is that the powder starts out the same R22 & MRP but different flame retardents are used on MRP. If you look at the color of both, MRP appears darker to me. I have also heard that R22 is bulk grade which can have +/- 10% lot to lot variation and that MRP is canister grade with a maximum allowable variation of 5%. So R22 can vary as much as twice the burn rate compared to MRP.. This seems true to what I have seen in lot to lot variation, almost none with MRP but some lots of R22 can vary between burn rates from the 4831 range to 7828 or even close to H1000.
I won't stop using R22 but I do want to explore alternate loads with R23 & R16 for the same applications. R16 is very promising being close to H4350 but usually with higher velocities. R16 & R26 are denser so may suit the Roberts well as they have with the 6mm Rem, 243 and the 25-06.
