RMR 124gn Matchwinners data

[Sequins]

Howdy folks,

I just ordered a thousand RMR 124gn truncated cone FMJ rounds and I'm looking for some advice on this bullet. To date I've only ever reloaded normal FMJ RN in 9mm so I'm curious on seating depth and load data.

For 124gn FMJ RN I like using CFE Pistol so that's what I'm gonna try here too to start. My RN data likes 1.150" but these TC bullets fail the plunk test at this depth and want to go deeper- but how deep? I'm liking 1.100" for passing plunk on all my barrels but curious about your thoughts.

As for charge weight the bearing surface "looks about the same to me" but the shorter OAL will add pressure, and that's not very scientific nevertheless at 0.050" shorter I'm thinking I want to consider my max only a bit lower, so if my data says 4.9gn - 5.5gn of CFE Pistol @ 1.150" I would be good to try 5.0, 5.1, and 5.2 to start hunting for a medium-hot load I like?

Thanks for your thoughts and Merry Christmas

 

[Jim Watson]

Sounds like a reasonable approach. Got a chronograph? I would adjust for velocity.

 

[AVirginian]

I shoot a lot of plated 124gr FP with CFE Pistol. 5.0, 5.1gr yield over 1100fps.

YMMV

 

[greentick]

1.080 is what I used. Works in the EGW chamber checker and and for sure in a Glock plunk test. They like the Lee FCD and groups were tighter.

ETA: RMR Matchwinners 9mm FP in 115 and 124gr

 

[Bottom Gun]

I've been loading the 124 gr Matchwinners to an OAL of 1.090. That has worked well in everything I've used it in. I've had good luck with Bullseye and Win 231 powders.

 

[Sequins]

Thanks guys.

 

[Unclenick]

If your load data starts at 4.9 grains, start at 4.9 grains. Three times in my life I have run into situations where that lowest listed charge was already maximum for the gun I tried it in. It's uncommon, just not impossible and all you need is one test load each at 2% increments of maximum. Also, Western Powders, unlike the others, recommends a 15% reduction from maximum for pistol load starting loads, and I suspect seating depth variation plays a role in that suggestion.

As to the seating situation, you can do better for an estimate. You want to determine how much empty powder space is under the RN FMJ and then what percent of that space is occupied by the powder charge. For the more deeply seated bullet, recalculate the space under the bullet and divide it by the space under the other bullet and multiply the powder charge by the result. This will give you lower pressure than the original, but not a lot lower and is within reason for the range you will be working in. Do not try this when the powder space is larger, as that will raise the pressure a bit.

 

[jetinteriorguy]

I just start seated long and then keep plunking and seating until it plunks. Then I seat .020 deeper and leave it. This allows for variations in bullets, powder fill, brass volume, and equipment when seating. Then I start with a recommended starting load and work my way up, but always be careful to avoid a compressed load regardless of a recommended max load. I do this with my CZ since it has the shortest lead of all my pistols.

 

[Sequins]

I got some advice elsewhere that these bullets like seating to 1.065" COAL and that's almost a tenth of an inch shorter than my 1.150 data. I'm going to buy Quickload I think for a better start, as 4.9 is above max for other truncated cone bullets at that length. 4.7 or 4.8 might be closer to my max at such a short depth.

 

[Unclenick]

If you have the bullet length correct and your actual case capacity correct, QuickLOAD automatically shows the space under the bullet and it gives you the option to enter your load either as a percent fill of the powder space or as the charge weight in grains, then automatically calculates whichever one you did not dictate. So, if I enter the case water overflow capacity and the bullet length and shape and the COL and 4.9 grains of powder with one bullet, it will show the % fill (i.e., load density) automatically. I can write that and the peak pressure down, then change the COL or the bullet seating depth directly, and it will show the change. I can then re-enter the % case fill and it will calculate the new charge weight automatically and show the peak pressure. I can then tweak the powder charge to match the peak pressure for a final number.

Keep in mind that QuickLOAD's powder data has come from measuring samples, and those can sometimes be higher or lower than average, so the pressures may not match what Hodgdon puts up. But if you ignore the exact pressure and use the ratio of change in pressure, you get very good charge adjustment numbers.