reloading for a MP9 (help with COL)

Avenida

Avenida

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I have been trying to reload for my mp9, which I do not have with me NOW (stays in the range until I get my ATT), but before I reload 1000 rounds for it to find that I have reloaded for the wrong COL I wanted to ask you guys.
Manual says that COL for 124 RN LEAD/FMJ should be 1.169, I have made a few rounds and brought them with me to the range today and used the barrel as a gauge, here are the results
1.169 fits but it seems to rub the rifling a bit
1.160 fit obviously better, still some minor rubbing.
I went all the way down to 1.140 in 0.005 increments and 1.145 seems to be prety good, with minimal, almost no rubbing but there is some.
1.140 seems to be ok.

I am hoping that someone with a mp9 can tell me what COL is working for you. I am using CAMPRO bullets, rounds nose, in 124 grain weight.

I have loaded 50 rounds at 1.169 that I have not shot yet, and I thinking to lower them down to 1.140. These loads have charged with 4.3 grains of WSF (max for 124 RN LEAD is 4.7) so my question is, is it safe to lower the bullet down to 1.145 with that charge? I assume it is, but before I blow the gun and my hand up I would like some feedback first.

CAMPRO website has no info about COL and manuals and other info says to use whatever COL works for your gun, just to make sure that you are starting out with me min load and work your way up while you look for pressure signs without going over the max load).

Thanks for any advice you can give me on this, hopefully I can get some loaded tonight.
Cheers.
 
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Ganderite said:
That seems long. I load mine around 1.125"

bring your mag and barrel home with you. Ammo has to fit both.
Click to expand...

Yep.

Round nosed bullet can be seated out further than flat nosed or JHP's. Somewhere between 1.100 and 1.150 is likely going to be the right OAL for your load.

Pistol reloading isn't like rifle. Seating the bullets out to nearly touch the rifling almost always will result in a load that doesn't feed properly.
 
Thanks! yes I did not try the mag, but I did measure Factory ammo and the MP9 can shoot Blazer Brass in 124 and 115, 1.145 and 1.15X respectively. So if I load to 1.140 I should be fine, or not, I will find out doing some more experimentation I assume.

What happens with powder charge while you adjust COL. I assume starting out at min load and working my way up, but I have some loaded at 4.3 grs (min is 4.0). Is it safe to adjust COL and shoot those? I am thinking it is, or am I being careless.
 
Ganderite said:
That seems long. I load mine around 1.125"

bring your mag and barrel home with you. Ammo has to fit both.
Click to expand...

+1. Don't even worry about measuring with calipers, just adjust your OAL until it fits.

Many people tend to over-think some of the numbers in the manual. The OAL that any given manual lists is only valid with the same bullet and in the same gun or test barrel that was used to develop the data. Load data is more of a guideline than an exact recipe.
 
mmattockx said:
Sound advice. A loaded round should drop into the chamber fully and fall out of the chamber under its own weight.Mark
Click to expand...
Excellent short summary.

I like to go one step further;
After the loaded round drops into the chamber, I press hard on it with my thumb and then make sure that it falls out under it's own weight.
Guarantees that I'm not contacting rifling.
 
Shorter increases pressure(a concern with 9mm and .40), and could be less accurate, changes balance of ctg, with occasional misfeed(ie chimney). Use the info from several books, ck your barrel gauge, and adjust as required. I would never load 1000 for a new handgun w/o testing. Be well
 
"...124 RN LEAD/FMJ..." Those will be two diffferent loads. Do not use jacketed bullet data for cast bullets.
Hodgon shows 1.169" for the cast bullet. 1.125" for a 125 grain jacketed. In any case, if the cartridge drops into the chamber(you can do this at home. No need to wait until you're at your club) and sits correctly, it'll do nicely. A few thou difference doesn't matter.
 
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