RMR 124 MPR JHP oal

[RMH]

I just received a great care package as a PIF from Dudedog. It has a variety of bullets from RMR for me to try out. One of which is the new 124 MPR JHP. In doing a plunk test, the bullet just cleared the lands at a length of 1.038. Thinking this was very short and I was doing something wrong, I tried 4 more cases and bullets. The results were 1.037 to 1.039. From my limited knowledge, that would make my max working length around 1.030. That would make the bullet seating depth of .282 into the case. That doesn't seem to leave much wiggle room for powder. In reading another thread on this bullet it seem that a lot of you were getting working lengths from 1.080 to 1.125.

Does any one else have to load this bullet that short? If so, could you share what powder you used and the results. Right now the only powder I have is W231. I will have the opportunity to pick up something else next weekend if I need to.

I forgot to mention this is for a Taurus pt809 9mm

 

[Doublehelix]

Sorry, I am one of those guys loading at 1.125". But I do have to say that I am loving these bullets. Don't give up, find a good load for them, you are going to love them!

 

[Walkalong]

The results were 1.037 to 1.039.

That's pretty short, and yes, it will affect pressures. Start low and work up very carefully in .1 increments. I had to go short at 1.070 for my Shield, but that's even shorter.

W-231 should work just fine.

They can shoot very well with the right charge. The BE-86 load was a little warm.

 

[LiveLife]

RMR ... 124 MPR JHP. In doing a plunk test, the bullet just cleared the lands at a length of 1.038. Thinking this was very short and I was doing something wrong, I tried 4 more cases and bullets. The results were 1.037 to 1.039.

Does any one else have to load this bullet that short? If so, could you share what powder you used and the results. Right now the only powder I have is W231

RMR 124 gr MPR JHP averages 0.558" in length and I need to seat them to 1.040" OAL (see round on the right of picture) to fully chamber in my Lone Wolf barrel with almost no leade.

- 1.125" fully chambered in older Lone Wolf barrels (with longer leade)
- 1.120" fully chambered in KKM barrel
- 1.040" fully chambered in newer Lone Wolf barrel (with almost no leade)


At 1.030" OAL, 4.2 gr charge of W231/HP-38 is max powder fill for 0.558" length bullet:

1.030" - 0.558" = .472" Max case fill

My resized cases averaged .750" so I measured .278" (.750" - .472" = .278") down from case mouth and marked the inside of case.

When I filled the case with W231/HP-38 to the mark and weighed the charge, it was 4.2 gr.


Since Max Case Fill is 4.2 gr and Hodgdon's published max charge is 3.3 gr at 1.069" OAL/COL, I don't believe powder compression will be your concern. Here's Hodgdon's load data for 125 gr Hornady HAP (Since most jacketed bullet weight varies around 1 grain, I interchange load data for 124/125 bullets) - http://www.hodgdonreloading.com/data/pistol

125 gr Hornady JHP W231/HP-38 COL 1.069" Start 2.8 gr (753 fps) 25,300 PSI - Max 3.3 gr (876 fps) 33,600 PSI

Since you are using shorter 1.030" OAL than published 1.069", you could reduce the start/max charges by .3 gr and start at 2.5 gr and work up to 3.0 gr.

That's pretty short, and yes, it will affect pressures. Start low and work up very carefully in .1 increments. I had to go short at 1.070 for my Shield, but that's even shorter.

W-231 should work just fine

+1. Perhaps you can load 2.4, 2.6, 2.8 and 3.0 gr test rounds to see how they cycle the slide and which load produces best accuracy.

 

[Walkalong]

Perhaps you can load 2.4, 2.6, 2.8 and 3.0 gr test rounds to see how they cycle the slide and which load produces best accuracy.

Sounds like a plan, but I would not pass over 2.9.

 

[LiveLife]

Then how about 2.3, 2.5, 2.7 and 2.9 gr test loads?

 

[ray15]

It takes ~1.03" OAL with this bullet to fit in a SAAMI-minimum 9mm Luger chamber. Most guns will have some leade and therefore tolerate longer OALs. I was fully expecting seating them this deep to increase pressures, but I've found no issue when I do.

I'm using CFE Pistol, and expected to stop well short of the 5.1gr. max Hodgdon lists - but ended up at just that. This surprised me because when I seat the RMR in-house FMJs to where they clear a minimum chamber it definitely does increase pressures compared to the published data. I run 5.4gr max with the RMR IH 115gr. FMJ versus the book max of 5.9. I was expecting the MPR JHP to be a similar situation, but in my gun the book max of 5.1 produced safe velocities and pressure with it.

 

[NR53]

It takes ~1.03" OAL with this bullet to fit in a SAAMI-minimum 9mm Luger chamber. Most guns will have some leade and therefore tolerate longer OALs. I was fully expecting seating them this deep to increase pressures, but I've found no issue when I do.

I'm using CFE Pistol, and expected to stop well short of the 5.1gr. max Hodgdon lists - but ended up at just that. This surprised me because when I seat the RMR in-house FMJs to where they clear a minimum chamber it definitely does increase pressures compared to the published data. I run 5.4gr max with the RMR IH 115gr. FMJ versus the book max of 5.9. I was expecting the MPR JHP to be a similar situation, but in my gun the book max of 5.1 produced safe velocities and pressure with it.

Thanks for the info. I'm pretty much in the same boat. The only powder I've got is True Blue. It shoots well with 115 grain Hornady HAP, but with the RMR in- house 124 JHP loaded to 1.03 OAL accuracy pretty much sucks. I can't find BE86 or even Unique locally, so the 124's are on the shelf until I can find something different. If the accuracy is good with CFE Pistol, I'll give it a try.

 

[LeftyTSGC]

FWIW,

Went out and shot with a Sig P320 and a JRC 9mm Carbine. Loaded both OAL to 1.08.
Bullet/Powder/Powder weight/OAL/no. of rounds and FPS/SD/ES

124gn RMR MPR BE-86 5.1gn 1.08 10/1037 13 43 P320
124gn RMR MPR BE-86 5.1gn 1.08 10/1284 15 37 JRC 9mm

dont have a picture of the shots but very tight groups. Loaded short to accommodate the JRC 9mm. I still had a little more room to up the powder if needed.
but these shot fine.

LeftyTSGC

 

[Walkalong]

124gn RMR MPR BE-86 5.1gn 1.08 10/1037 13 43 P320

That is a great plinking load velocity with 124/5 Gr bullets. Mine is a touch faster at 1050ish from 5" barrels.

 

[RMH]

RMR 124 gr MPR JHP averages 0.558" in length and I need to seat them to 1.040" OAL (see round on the right of picture) to fully chamber in my Lone Wolf barrel with almost no leade.

- 1.125" fully chambered in older Lone Wolf barrels (with longer leade)
- 1.120" fully chambered in KKM barrel
- 1.040" fully chambered in newer Lone Wolf barrel (with almost no leade)


At 1.030" OAL, 4.2 gr charge of W231/HP-38 is max powder fill for 0.558" length bullet:

1.030" - 0.558" = .472" Max case fill

My resized cases averaged .750" so I measured .278" (.750" - .472" = .278") down from case mouth and marked the inside of case.

When I filled the case with W231/HP-38 to the mark and weighed the charge, it was 4.2 gr.


Since Max Case Fill is 4.2 gr and Hodgdon's published max charge is 3.3 gr at 1.069" OAL/COL, I don't believe powder compression will be your concern. Here's Hodgdon's load data for 125 gr Hornady HAP (Since most jacketed bullet weight varies around 1 grain, I interchange load data for 124/125 bullets) - http://www.hodgdonreloading.com/data/pistol

Since you are using shorter 1.030" OAL than published 1.069", you could reduce the start/max charges by .3 gr and start at 2.5 gr and work up to 3.0 gr.

+1. Perhaps you can load 2.4, 2.6, 2.8 and 3.0 gr test rounds to see how they cycle the slide and which load produces best accuracy.

Thank you. That was a lot of work you put into this. I was very surprised to see such a low charge range. Very similar to the range I used to work up a 380 load.

I also want to thank everybody here on THR for all your years of wisdom and the willingness to pass it on to the ones that are just starting such an interesting and rewarding hobby.


Russell

 

[LiveLife]

You are very welcome, anything for a fellow THR member! '

As others posted, reloading 9mm can require additional consideration due to being a small volume case and small changes like shorter OAL/deeper bullet seating depth can have significant effect on chamber pressures.

 

[ray15]

Thanks for the info. I'm pretty much in the same boat. The only powder I've got is True Blue. It shoots well with 115 grain Hornady HAP, but with the RMR in- house 124 JHP loaded to 1.03 OAL accuracy pretty much sucks. I can't find BE86 or even Unique locally, so the 124's are on the shelf until I can find something different. If the accuracy is good with CFE Pistol, I'll give it a try.

CFE Pistol is a versatile powder that tends to produce outstanding accuracy at near to or max loadings. If you want 1080-1150fps with a 124gr. it's a great choice. If you want more plinking-level velocities I'd probably recommend W231/HP38.

I've only tested the accuracy in a superficial fashion. It's definitely minute-of-bad-guy, but I'm not sure it's much more. I will probably lengthen the OAL as much as my guns allow, but do initial load development at an OAL that clears a SAAMI-minimum chamber so I know what the worst-case pressures look like.

 

[Ruger 15151]

- 1.125" fully chambered in older Lone Wolf barrels (with longer leade)
- 1.120" fully chambered in KKM barrel
- 1.040" fully chambered in newer Lone Wolf barrel (with almost no leade)


At 1.030" OAL, 4.2 gr charge of W231/HP-38 is max powder fill for 0.558" length bullet:

bds

1. Have you reduced your BE-86 5.2gr loads because of this new longer bullet as well?

2. Have you seen any accuracy difference in your testing (Pistol) with this new shorter bullet?

 

[NR53]

CFE Pistol is a versatile powder that tends to produce outstanding accuracy at near to or max loadings. If you want 1080-1150fps with a 124gr. it's a great choice. If you want more plinking-level velocities I'd probably recommend W231/HP38.

I've only tested the accuracy in a superficial fashion. It's definitely minute-of-bad-guy, but I'm not sure it's much more. I will probably lengthen the OAL as much as my guns allow, but do initial load development at an OAL that clears a SAAMI-minimum chamber so I know what the worst-case pressures look like.

Thanks Ray. I'm looking for more of a plinking load...minute-of- fun. I've got 1K of these and I want to have some fun with them. I'll look into W231/HP38..or hopefully BE86 if it ever becomes available locally.

 

[Dudedog]

CFE-P has shot well for me in midrange loads in 9mm with 124/125gr and 147gr bullets.
I have had better results loading charges in the middle of the range with CFE-P than I have with BE86 when using 124/125s.
With mid range 147s BE86 and CFE-P are to close for me to call a winner.
Of course every gun has it's likes and dislikes.

 

[LiveLife]

1. Have you reduced your BE-86 5.2gr loads because of this new longer bullet as well?

2. Have you seen any accuracy difference in your testing (Pistol) with this new shorter bullet?

I haven't done load development with BE-86 and RMR's new "shorter" MPR JHP bullet but plan to reduce start charge.

I plan on doing comparison accuracy testing with both old and new bullets.

 

[Walkalong]

I've only tested the accuracy in a superficial fashion. It's definitely minute-of-bad-guy, but I'm not sure it's much more

The targets I posted were shot at 7 yards, well within minute of bad guy.