MPX Throat Reamming

[IGOTTHEPOO]

I am having issues reloading for my MPX. I currently am trying to load lead bullets that i mold myself and size to .356 (both 125 and 147 gr). I was wondering if anyone has had their MPX 16" carbine barrel reamed? If so, could you suggest someone? I had read in another forum that someone tried but the barrel was chrome-lined (though i am unable to confirm this).  Any help would be appreciated.

Edited December 25, 2017 by IGOTTHEPOO

[Rolex]

I would not shoot lead bullets in the MPX- Colt style blowback- maybe-

HiTek yes- with the correct powder- JHP and FMJ are a go to for most.

Lead will melt to a point and clog up the gas system-

[IGOTTHEPOO]

I would not shoot lead bullets in the MPX- Colt style blowback- maybe-
HiTek yes- with the correct powder- JHP and FMJ are a go to for most.
Lead will melt to a point and clog up the gas system-

I forgot to add that they are powder coated.

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[Shadyscott999]

42 minutes ago, Rolex said:

I would not shoot lead bullets in the MPX- Colt style blowback- maybe-

HiTek yes- with the correct powder- JHP and FMJ are a go to for most.

Lead will melt to a point and clog up the gas system-

 

MPX isn't blowback.  But you are correct they do not like soft bullets.  

[Rolex]

I know that- is gas operated piston--Colt style maybe- 

[MHitchcock]

The MPX really isn't a short chamber...at least mine isn't...

[Aircooled6racer]

Hello: I load my MPX to 1.145" OAL with coated, plated and jacketed bullets. No feeding problems or lead buildup. Thanks,Eric

[IGOTTHEPOO]

Hello: I load my MPX to 1.145" OAL with coated, plated and jacketed bullets. No feeding problems or lead buildup. Thanks,Eric

What coated bullet and weight do you use?

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[Aircooled6racer]

Hello: I am using Acme coated bullets that are 115 grains. Thanks,Eric

 

[MemphisMechanic]

Look into changed to a truncated-cone mold for your 124s...

 

 

In the same short-chambered M&P an Acme 124gr RN coated needed to be under 1.110”.

(I was loading the bullet on the left)

 

 

 

I could load the Black Bullets 125 TC at 1.150” in the exact same barrel:

 

Profile matters. A lot. It’s all about the ogive in shorter chambers. And I’ll bet the MPX has a hardened barrel,  not chrome lined like an AR15. You cannot ream the chamber on an M&P or XD or Glock for this same reason: they’re hard enough to chew up reamers.

[Neomet]

^^^^^^^  This.  Ogive makes a huge difference in the OAL of the projectile (and you may well know this already).  The MPX is about as deep throated as I have seen in a 9mm and I would personally not be inclined to ream the chamber out but rather would work with the OAL.  But that is just me.  

[sitw]

Normally, on a pistol I would say get it reamed.  But for a PCC with what is most likely a nitrided barrel, I'm with Memphis and Neomet.  Nothing wrong with loading shorter if that is what the chamber and bullet require.  And at the pressures you will be at loading for PCC power factor, I wouldn't worry about that being an issue at all.