Norma MRP for 257 Roberts?

[choprzrul]

Thread title changed.....

Does anyone have experience using Alliant's ReLoder 26 Norma MRP in a 257 Roberts?

The latest Alliant printed data has it listed for a 120gr Partition.....so it must be a viable powder?

Some background info:

Ruger M77 that will be getting a Bartlein barrel one of these first days
New Winchester +P brass
Speer 120gr BTSP #1410 projectiles
2.900" OAL

I'm just curious if anyone else has used this powder? It looks like it could give me as much as 100fps advantage over Ramshot Hunter or H4350....so it's intriguing to me. I am concerned about lighter loads when doing my initial load ladder testing, so I'm thinking about a Federal #215M primer to light it?

All thoughts and opinions are welcome.

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[kevins750]

do you have some RL26 on hand?
my personal experience and many others is it seems almost
impossible to find, even before CV19.

I have moved away from those (popular) powders
and tried to develop loads with alt powders that
are more available.

wish I could have been more help, and good luck with the development.

BTW. I do like the hunter powder in the '06 case, maybe try searching some loads with RL17 RL19 RL23, hunter, magpro, magnum, MRP. usually easier to find(pre CV19)

[choprzrul]

do you have some RL26 on hand?
my personal experience and many others is it seems almost
impossible to find, even before CV19.

I have moved away from those (popular) powders
and tried to develop loads with alt powders that
are more available.

wish I could have been more help, and good luck with the development.

BTW. I do like the hunter powder in the '06 case, maybe try searching some loads with RL17 RL19 RL23, hunter, magpro, magnum, MRP. usually easier to find(pre CV19)

No, I do not. And now that you say something.....I can't find it either

I was able to find a couple pounds of MRP, so I put together an order and will try it out.

Thank you sir.

....now I'm wondering if anyone has tried MRP in a 257 Roberts??

.

[elk hunter]

If you were here I would trade you a pound of 26 for something I can use. I don't use 26 anymore so it will just have to sit and hope I get another caliber It will work well in. I never used MRP so no help there and I will have to look up what I did use in my 257 Bob and AI before I can speak about it.

[elk hunter]

No, I do not. And now that you say something.....I can't find it either

I was able to find a couple pounds of MRP, so I put together an order and will try it out.

Thank you sir.

....now I'm wondering if anyone has tried MRP in a 257 Roberts??

.

Powders that worked well in my .257 Roberts were IMR 4320, IMR 4350 and Win. 760. They all worked pretty much equally well, IMR 3031 to a lesser degree.

[Fjold]

MRP will probably work well with the heaviest bullets (115 -120) but in the regular hunting weight bullets you probably can't get enough of it in the case to maximize their velocities.

[Elgatodeacero]

https://www.norma-ammunition.com/en-gb/reloading-data/257-roberts

[FLIGHT762]

Norma MRP and Alliant RL-22 is supposed to be the very close to the same powder. There's a lot of cross referencing info on the net about Norma powders and Alliant powders.

Speer had some data using RE-22 with the heavier, 117 - 120 gr. bullets.

You can look for RE-22 data on the 257+P Roberts, start low and work up.

[Divernhunter]

H-450 works great with 120gr Swift A-Frames
Wish I could still find some

[pennstater]

Varget. That's what you want. IMR4064 if you want more velocity.

[choprzrul]

Varget. That's what you want. IMR4064 if you want more velocity.

From QuickLoad using 2.900" OAL and a Speer 120gr BTSP from a 20" barrel....staying just below 57,000psi....max powder charges listed below:

Varget................40.2gr == 2749fps
IMR4064............39.5gr == 2745fps

Norma MRP.........49.7gr == 2903fps
Ramshot Hunter...46.2gr == 2831fps
IMR4831............44.7gr == 2799fps
ReLoder 16.........43.6gr == 2859fps

It looks like a 'free' 50-150fps can be achieved over both Varget and IMR4064. The MRP and RL-16 both have de-coppering properties as a bonus.

Getting 2800fps out of that 20" barrel keeps it ballistic out past 1100 yards....

.

[Elgatodeacero]

Your Quickload data above for Norma MRP is 2.1 grains OVER Norma’s maximum charge for a 120 grain bullet. I strongly suggest OP uses Norma load data.

MRP is a very good rifle powder.

[pennstater]

Hmm. Haven't loaded for bottle neck cartridges for a while, mostly handgun rounds in lever rifles, so, I'm a little behind. But, I'd be more interested in accuracy than a bit more velocity. That's where I was going with this.

[choprzrul]

Your Quickload data above for Norma MRP is 2.1 grains OVER Norma’s maximum charge for a 120 grain bullet. I strongly suggest OP uses Norma load data.

MRP is a very good rifle powder.

What is Norma listing for OAL with that load?

At 2.900" OAL, internal ballistics is going to change I suspect....

.

[choprzrul]

Hmm. Haven't loaded for bottle neck cartridges for a while, mostly handgun rounds in lever rifles, so, I'm a little behind. But, I'd be more interested in accuracy than a bit more velocity. That's where I was going with this.

Tiny groups trumps all !!

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