New loads for RMR 124?s, RN & MPR, OALS?...

[Red Dog Leader]

Today did ?push/plunk & spin on the 124 Gr. RMR Full Metal Jacket Round Nose, 124 Gr. RMR Jacketed Hollow Point (Multi Purpose Round) for my SP-01.

Just curious what measurements others are getting.

 In my barrel the MPR'S are now at 1.060, the RN?s avg 1.133 with push so going with 1.125.

Thanks, Red

[IDescribe]

I don't load these, so I'm not giving you my numbers, but...

With the MPR, we have had people coming up with anything between 1.04 and 1.06, so that number makes sense.

I believe the RMR FMJ-RN has push-tested longer than 1.169 (which is the max for a standard 9mm magazine), so people have loaded 1.16 or shorter.  I am surprised to see it push-testing down to 1.133.

I would recommend giving the FMJ-RN another go.  Maybe even load a dummy -- size, bell, seat, crimp (no powder, no primer) -- and see if that 1.160 will plunk and spin in the barrel.  That 1.133 seems short.

Does the FMJ bullet have an exposed lead base?

[Red Dog Leader]

Thanks, IDescribe

Yes, exposed lead base.

It does seem short, hence my post.
I load PD RN ~1.140 ish with good results.

I would recommend giving the FMJ-RN another go.  Maybe even load a dummy -- size, bell, seat, crimp (no powder, no primer) -- and see if that 1.160 will plunk and spin in the barrel.  That 1.133 seems short.

Just did your above suggestion. No go at 1.160.

Revisited this thread  https://czfirearms.us/index.php?topic=57666.0 and reread Wobblys push test instructions

Redid test just now: 15 Win cases, 3 different bullets with 5 different cases.
Hi was 1.149
Low was 1.140
AVG was 1.143
SO, do you go with low, hi or avg...

1.143 - 0.015 = 1.128....


Thanks a lot, Red

[Mods added quote]

[IDescribe]

You have a dummy now.  Just keep shortening it a few thousandths at a time until it plunks and spins.  That will tell you the max with certainty.

[Red Dog Leader]

Will do...

[George16]

You mean to say,

1.143 - 0.015 = 1.128

[Mods: You are correct. A "1" was left out of the original result, which has now been corrected. However, a telescoping bullet-in-case cannot be measured to 4 decimal places, therefore we'll simply work with 3 decimals.]

[Wobbly]

Redid test just now: 15 Win cases, 3 different bullets with 5 different cases.
Hi was 1.149
Low was 1.140
AVG was 1.143
SO, do you go with low, hi or avg...

1.143 - 0.015 = 1.128....

Thanks a lot, Red

One of the objects of subtracting the 0.015" is to make sure all your reloads work every time in your barrel. Another is to make up for wide variations in your OALs.

If your seater fits the bullet's ogive and you're lubing your cases, and your resulting OALs vary very little, then you can use the Average result (which is closer to the Low number anyway) allowing you to go with 1.130" as your OAL. (If your Average had been much closer to the Hi of 1.149", then my answer would have been different.)

If you are new to reloading and your OALs are still seeing wide variations, then use 1.125" as your OAL. That extra 0.005" will give you some safety padding to insure that every round fits and fires safely.

So to answer your question, there's not one, single, definitive way it's always done. Part of reloading is science and part is good judgement. You simply want to err toward safety.

 

[Red Dog Leader]

If your seater fits the bullet's ogive and you're lubing your cases, and your resulting OALs vary very little, then you can use the Average result (which is closer to the Low number anyway) allowing you to go with 1.130" as your OAL.

Thank you sir, have 10 loaded up and will check them out latter today.

[George16]

I load the 124 FMJ RN with 4.1 Gr of Winchester 231 @ 1.125-1.128 for my shadow 2 and TSO. I also use the for my czechmate a 1.150-1.152 using 6.41 Gr of CFE pistol for open major.

RMR?s FMJ RN has a nice ogive that allows me to seat it longer for major PF loading compared to their jhp.

[Red Dog Leader]

Well all went well with the 10 test rnds...

I load the 124 FMJ RN with 4.1 Gr of Winchester 231 @ 1.125-1.128 for my shadow 2 and TSO. I also use the for my czechmate a 1.150-1.152 using 6.41 Gr of CFE pistol for open major.

RMR?s FMJ RN has a nice ogive that allows me to seat it longer for major PF loading compared to their jhp.

good to know Geo16.

Have a wee bit left of N320, planed on trying out W231 next in 9mm, since a lot use it here. Love it for my .45 200SWC....

[Dan_69GTX]

I do not use the RMR 124 JHP Multipurpose stuff in the pistol.  Loads WAY tooo short!

I'm using them up in other guns.

For reference I am loading their 124 RN jacketed in the 1.130 range

[Wobbly]

Thank you sir, have 10 loaded up and will check them out latter today.

Well all went well with the 10 test rnds...

The best "test" is NOT to see if they fire. Of course they'll fire, you've gone through a lot of trouble to produce live ammunition. The test is to see if any of the 10 were long enough in OAL to bury the ogive of the bullet into the lands of the barrel. Because having the ammunition presented that way to the rifling would create an unsafe condition in that it would raise the chamber pressure and/or possibly make it where the pistol would fire out of battery.

So the "test" is to take the naked barrel and chamber all your "test rounds". All of them should freely spin in the chamber, thereby indicating the bullet is not touching the rifling.

We do the mathematical "push test" method first becasue we want to know by how much the bullet misses the rifling. The "spin test" merely tells us they miss, but not by how much, thereby making it hard to predict that ALL rounds will have the needed clearance.

In this way we always err toward safety.

Hope that makes sense. 

[Red Dog Leader]

So the "test" is to take the naked barrel and chamber all your "test rounds". All of them should freely spin in the chamber, thereby indicating the bullet is not touching the rifling.

Sorry, should have elaborated...yes, they where all checked with barrel out, then fired.

[Wobbly]

Sorry, should have elaborated...yes, they where all checked with barrel out, then fired.

Excellent ! You're on your way.