OAL for MP9


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Quoheleth
March 17, 2008, 12:43 PM
Am reloading some Speer 125gr LRNs for my MP9 using 3.6gr Universal. Their minimum load is 3.8; I'm starting a little low deliberately. According to Hodgen's website, 3.8 should produce @990fps, so this will be a little less than that - I hope a nice target/plinking load that doesnt lead.

Question about OAL. My Lee manual lists OAL as 1.169 (I'll assume that's with a 115gr FMJ). Hodgen's website gave OAL as 1.125 with a LCN and 1.09 with a Sierra 125gr FMJ. I made a couple rounds and, remembering someone's post about cartridges not chambering, tested them [CAREFULLY] for chamber fit. At 1.169, they were too long, I guess engaging the rifling. Even at 1.130, the slide did not seem to completely close on my MP9. I've dropped OAL to 1.24 and they seem to chamber just fine.

Is this safe, or am I risking a pressure problem?

Oh, and yes - I checked case length of a random sample. Every one right on the money - .754.

Thanks,
Q

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rcmodel
March 17, 2008, 01:07 PM
If you are starting .2 grains under a starting load, seating depth is not going to have any impact on safety.

Do what you gotta do to get them to chamber.
Then in all likelyhood you will still need more powder to get the gun to cycle.

rcmodel

Quoheleth
March 17, 2008, 01:14 PM
So, go ahead and bump it up to a 3.8 load?

rcmodel
March 17, 2008, 01:23 PM
It's never a good idea to go below a listed starting load.

It's called a "starting load" for several very good reasons.

rcmodel

BattleChimp Potemkin
March 17, 2008, 01:48 PM
It may squib or fail to even cycle the gun. Get a little more aggressive :) Leading isnt that bad :D Just kidding. Go for the 3.8, dont mess around under a minimum load as rcmodel said. Had some .38 that stuck in the barrel b/c I under loaded. Girlfriend kept firing until 4 bullets were lodged in the gun (convieniently firing when I was on the other side of the range, should have been there to watch her).

Quoheleth
March 17, 2008, 02:25 PM
Ok...3.8 it is. I made 3 of the 3.6 grain load, and then decided to go ahead and kick it up to the minimum.

If I gotta scrub lead, well, what's time between three friends - me, Smith and Wesson?:p

Back to my original OAL question. So, with autos, the published OAL is sort of a guideline on the lower end of the power range? Some of it depends on the gun? I guess if I were loading top-end performance, OAL would be more critical? I've only loaded .38 and medium-level .357 prior to this, and there OAL length wasn't an issue - as long as it doesn't hang out of the front of the cylinder, it's OK.

Thanks, guys.

Q

JDGray
March 17, 2008, 09:52 PM
Starting loads are usually nothing more than 10% under the max load. I shoot lots of reduced loads, as long as you don't drop it too far your gonna be ok. I shoot alot of Power Pistol loads in 9mm & 40, most of them a bit under start data by a tenth or two, all run flawless in my stock sprung guns, and more accurate.:)

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