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MPX Maintenance Schedule

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Anyone else running the 13% reduced recoil springs by ILWT, and at what PF? What benefits, gains did you experience?

 

To the OP:

"Tappet and gas plug rings - as needed but no more than 5k (gas plug isn't as important but prob worth doing at the same time)" 

You "replace" the rings every 5k rounds?

 

 

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I’m curious on the reduced power springs as I’m going to be tuning my 4.5 barrel. 

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I was told on the MPX reloading data page that the .0625 port hole in the ILWT barrels is too much gas. 

jlo86cj

uses the .052 restricted gas plug and 20% increased power springs. He just ordered another ILWT barrel with .052 port so he can use the open gas plug.

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Too much gas as in it's unlocking too quickly and seeing accuracy issues? 

 

My Gen 1 has been great so far. I was trying to use power pistol since I had it laying around and it has a slower burn rate, but mine cycles TG and even Clays just fine and makes a soft gun even softer (3.4 Clays under a 124gr JHP)

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ILWT has a great spare parts kit, otherwise  call Sig 

 

anyone has anything else to add concerning reduced power recoil springs?!?!? 

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i have the -13% ones from ilwt. i bought the -20% but i am returning them for the +20% ones. robert advised me to do this to increase the dwell time of the bolt in battery to allow the small amount of gas i was making with 147's and fast powder have time to be used to maximum effect. also to very positively move the bolt forward and strip rounds off of very full mags under a lot of pressure. especially with how the low power hammer spring of my drop in trigger changes the timing of the bolt as it moves rearward.

 

my -13 springs have quite a few kinks in them that my stock springs never got. my stock extractor spring wore out in about 2k rounds.

 

i bought an ultra sonic cleaner for the gas plug/valve as nothing i did truly cleaned it. the tappet was easy to clean. i have a stock sig tappet and an ilwt tappet. i have a stock sig plug and an open gen 2 ilwt one.

 

(i run a timney trigger and had my gas port opened by zrt in a stock sig carbine barrel)

Edited by rowdyb

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After almost two years of tinkering with the MPX I've settled on running the +20 springs and tuning the gas to your load. I've seen improved accuracy as well as less abuse to the trigger. I did recently have the bolt carrier grenade, but I attribute that to running it over gassed for to long.

I have a 10.5 ILWT barrel with a .062 port, .052 gas plug and +20 springs. My load is Berry's 124 HBRN-TP and 4.0 grains on Alliant Sport Pistol. It's right at 132pf and runs perfect. It ejects at 2:00 about 10 feet.

I just ordered an 8" and Robert is leaving it .052. It should be just about perfect with an open gas plug. If not, I plan on opening it up in .001 increments until it's where I want it.

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