MRP temperature sensitivity??

[MAinAR]

Has any one checked different upper and lower temperature velocities with MRP in belted magnum loads, 7RM or 300WM?

Just wondering what to expect on velocity stability when temps change, I see about 1 to 1.5fps per degree with RL22 and wondered how MRP compares since it seems to be available to buy more regularly nowadays.

 

[skidmark]

I could be wrong but I believe RL22 is repackaged
MRP. Others may disagree. I also believe Norma uses MRP in
factory 340 ammo. And we know 22 is temp sensitive.
Just my 2 cents.

 

[rodell]

Some would say Rl22 is the second run of MRP. My data supports that with temperature sensitivity on RL22 but less so on MRP.

 

[Ridgerunner665]

Between the two...the average grain size is identical...I am of the opinion that it is the same powder, made on the same equipment...but is finished (coated) differently, and will behave similar n some cases, and not so similar in others.

MRP is black...similar in color to Reloder 15 or IMR 4895




Reloder 22 is grey...similar in color to H4350...

 

[Ridgerunner665]

Below is copied from one of my older posts here on this subject...I'm referring to RL22.

It's one of the most temp sensitive powders I've ever used...only Accurate 2230 is worse, among the powders I've used.

I tested it in 300 Win Mag...and got over 150 fps difference from 75 degrees to 90 degrees....and over 100 fps difference from 75 degrees down to 35 degrees, that's over 2 fps per degree...I'll accept 1.3-1.5 fps per degree (on the cooler side)...but any more than that and I'm looking for another powder...may have just been a bad lot, but it pretty much ruined RL22 for me.

Powder temp sensitivity does vary with cartridge dynamics....it probably works great in some rounds...and not so great in others.

I'm anxious to test MRP...and to be honest, I should retest RL22 in the Ackley...it's easier to get.

Those tests will be done soon (within a couple months)...side by side comparison, in detail.


Along these lines...I'm wondering if Reloder 23 is rebranded MRP...is 23 black and shiny?

 

[MAinAR]

Below is copied from one of my older posts here on this subject...I'm referring to RL22.

It's one of the most temp sensitive powders I've ever used...only Accurate 2230 is worse, among the powders I've used.

I tested it in 300 Win Mag...and got over 150 fps difference from 75 degrees to 90 degrees....and over 100 fps difference from 75 degrees down to 35 degrees, that's over 2 fps per degree...I'll accept 1.3-1.5 fps per degree (on the cooler side)...but any more than that and I'm looking for another powder...may have just been a bad lot, but it pretty much ruined RL22 for me.

Powder temp sensitivity does vary with cartridge dynamics....it probably works great in some rounds...and not so great in others.

I'm anxious to test MRP...and to be honest, I should retest RL22 in the Ackley...it's easier to get.

Those tests will be done soon (within a couple months)...side by side comparison, in detail.


Along these lines...I'm wondering if Reloder 23 is rebranded MRP...is 23 black and shiny?

Keep us up to date, I have been testing MRP at 70.2gr in 7mm Rem Mag with 140AB, I am seeing about 2fps/degree as well and this was just from 50 to 70 degrees so it concerned meas to how much effort to put into load development!

 

[SJB358]

Great info. I have ran a little MRP and liked it alot in my 7mm Rem Mag, but I have no real data about temp sensitivity.

 

[MAinAR]

With MRP I got 100fps swing from 40 to 80degrees at 69gr with 140AB in 7RM .......TOOO much!
MRP = 2.5fps/degree


With RL26 at 71.5gr all else the same I am seeing about 43fps........ not great but much better.
RL26 = 0.93fps per grain (basically 1 to 1.4 fps per degree)

Got to test COLD now and see.

 

[boomer68]

Interesting. So, I am assuming RL23 is the replacement for RL22? Is it made by Norma?

 

[MAinAR]

Interesting. So, I am assuming RL23 is the replacement for RL22? Is it made by Norma?

Comes from the Bofors Plant same as Norma's.