Mpx, post 700 round mark, looking for handload info that works please

[Venti30]

Just picked up a sig mpx, 8” barrel pistol that I’ll SBR after my trust runs its course and as many have reported, wouldn’t run medium book loads. Had tried running 115 and 124 grain over 4.5 grains of hp38 (Hodgdon range is 4.3 to 4.8), but no go, wouldn’t cycle, fte, ftf. Had to run about 300 factory rounds through it to get it loosened up first. 

After the 30p rounds of factory blazer 115 Grn, (what my home range had on hand) it would run 115 grain over 4.8 grains of hp38 at 1.100 coal hand loads, 99% of the time. 

I brought it home after a blistering range run of 500 rounds of the 115 plated lead round nose /4,8grn/1.100 handloads and was amazed at how dirty the gun was, particularly around the gas valve and tappet. The tapped and valve were stuck nearly solid, carbon seemingly permanently infused to the parts. 

Upon later reading, seems that some advise against plated bullets in the mpx, so my question to my esteemed associates is, given the mpx platform mentioned, does anyone have successful post 700 round count handload recipe for an mpx that they’d like to share?

Many thanks in advance,
JR

[MemphisMechanic]

Take the gun apart and take a good look at your gas port before possibly designing loads around a gun with a partially clogged one.

 

 

Edited April 25, 2018 by MemphisMechanic

[edwin garcia]

My load is 115 FMJ Precision Delta, with 4.3 gr of VV N320. OAL is 1.13". My MPX is a gen 2, 16" carbine. 

I have pushed it to around 1K without cleaning the valve. I however, I cleaned and oiled the bolt midway.

I currently clean the valve/tappet around 500, give or take. No issues so far.

Best of luck

 

[Dutchman195]

My Gen 1 MPX shoots a 135gr Bayou with 3.2gr of TG at 1.130 OAL

 

Never had a problem in probably 2k rounds. Maybe 500 suppressed. And I barely clean it. Have also shot 115 and 124 bayous through it that probably hovered around 1000FPS. No issues.