Sig MPX Routine Care and Feeding

[sdrr72]

I've gotten back to shooting, matches are happening, and I'm coming up on roughly 3k rounds through a Gen2 MPX.  I've got a ton of experience with Glock maintenance but not much with MPX.  What are the parts and replacement intervals to consider for proactive maintenance? 

 

 

 

[Bdh821]

Clean the entire gas system/gun every 1k rounds. Mostly gas system. Don’t over oil the moving parts. 
 

don’t use coated bullets. 
 

don’t use titegroup

 

 

[cnote]

I just always shoot some jacketed  bullets through the gun after using coated if that is a concern.  Works with a 22 and those filthy rounds.

[Bdh821]

2 hours ago, cnote said:

I just always shoot some jacketed  bullets through the gun after using coated if that is a concern.  Works with a 22 and those filthy rounds.

That won’t clean out the gas system.  I’m not concerned about the internals of the barrel. Who cleans their barrels now a days?!  
 

 
on another note of things to check, clean the extractor real well from the bolt and maybe replace the extractor spring stuff every season depending on round count. Cheap maintenance tho. Maybe new recoil springs once a year also pending round count. 

Edited November 30, 2020 by Bdh821

[Dan Sierpina]

Brian, 

 No Titegroup? What powder have you been using? 

[sdrr72]

I'm using plated bullets only with N320 right now.  Titegroup is a backup, but like Dan said, I'm not sure why Titegroup would matter.  It's dirty, but I am cleaning the gun regularly.

 

I know I need to change my Glock's recoil spring around 2k or cycling suffers.  I'm really more interested in things like that for the MPX.  What are the "parts" that end up being consumable with this platform?  What are the intervals for replacement other people have noted?  When do issues crop up, and how much use was noted when they happened?  Real world experience is greatly appreciated.  I've had no real issues at all so far, but like everything mechanical, that only lasts so long.

 

Thank you BDH821, this is the type of info I am looking for.

[jzuel]

Also running plated bullets with N320, runs very clean. Learned the hard way about coated bullets. 

 

I have the spare parts kit from Inleadwetrust + a couple of spare pistons and gas plugs to swap and speed up cleaning time. Titanium firing pin.

 

I clean it every 1200 rounds or so.

I'll start seeing FTF when the gas system gets clogged.

 

I usually replace the recoil and ejector springs every year, ~5000 rounds

 

 

[Bdh821]

On 11/30/2020 at 7:00 PM, Dan Sierpina said:

Brian, 

 No Titegroup? What powder have you been using? 

Dan,

If I were using a blowback, I’d have no issues with TG. I’m using HP-38 currently. Once I’m out of that I’ll use Alliant sport pistol as I’ve heard those are the 2 common powders used for the MPX.  I’m basically trying to keep the gun as clean as possible. TG leaves a very hard carbon buildup on the piston. All powders do, but TG is harder to clean IMO
 

I’d use N320 but since I’m a southpaw it kinda gasses me in the face and N320 doesn’t smell good haha. 

Edited December 2, 2020 by Bdh821

[Dan Sierpina]

5 hours ago, Bdh821 said:

Dan,

If I were using a blowback, I’d have no issues with TG. I’m using HP-38 currently. Once I’m out of that I’ll use Alliant sport pistol as I’ve heard those are the 2 common powders used for the MPX.  I’m basically trying to keep the gun as clean as possible. TG leaves a very hard carbon buildup on the piston. All powders do, but TG is harder to clean IMO
 

I’d use N320 but since I’m a southpaw it kinda gasses me in the face and N320 doesn’t smell good haha. 

I haven't seen Sport Pistol available for a while. 231 and HP-38 are the same powder, if you can find only one.

 

[Archangelgt]

What plated bullet you guys using for your MPXs? 

[sdrr72]

Xtreme here, 124g and 147g, depending on my mood.  I have a bunch of both.  Haven't decided what I like best yet.

[Bdh821]

15 hours ago, Archangelgt said:

What plated bullet you guys using for your MPXs? 

at this point, anything I can get.  I have xtreme and everglades plated 115s.   I have a bunch of 115 and 124 FMJ and JHPs too for when the plated runs out.  Again at this point, if you can only get coated bullets than it is what it is... you'll just have a tough time scraping the piston and build up on the comp.  I run my ammo on the faster side, 138-141pf which is around 1215fps.  

[Archangelgt]

9 minutes ago, Bdh821 said:

at this point, anything I can get.  I have xtreme and everglades plated 115s.   I have a bunch of 115 and 124 FMJ and JHPs too for when the plated runs out.  Again at this point, if you can only get coated bullets than it is what it is... you'll just have a tough time scraping the piston and build up on the comp.  I run my ammo on the faster side, 138-141pf which is around 1215fps.  

 

Thanks I've always reloaded coated, didn't realize jacketed were sold out. 

 

Anyone notice any differences between .355 vs .356 in the MPX. 

 

I've only fed mine factory American Eagle 147s and 124s.

[sdrr72]

For Xtreme:  the 124's I have are .355, and the 147's are .356.  My experience is that I cannot tell a difference in groups between the two at 50 feet or less.  I have not tried to shoot for group further than that.

[Bdh821]

4 hours ago, sdrr72 said:

For Xtreme:  the 124's I have are .355, and the 147's are .356.  My experience is that I cannot tell a difference in groups between the two at 50 feet or less.  I have not tried to shoot for group further than that.

I also did not notice any difference between .355 and .356 with my MPXs

[ck1]

I don't think coated bullets + MPX is necessarily always a disaster. I've shot ~10k of blue bullets out of a couple MPX's, ~8k through one gun (that now belongs to a buddy and is still going strong, think he shoots BBI or Galant's, coated something), and another ~2k on one I still own, no issues. Maybe I've been lucky, but the MPX gas system hasn't given me any grief from the coated bullets.

 

That said, some MPX's seem to be finickier than others, as I think I'm an outlier in the world of MPX maintenance and haven't really cleaned mine any more than anything else that gets shot a lot. I've just run them fairly wet and added lube pretty much before every outing, wiped down the bolt and got the easy to get to crud out every 1000rds or so, but no real soup-to-nuts cleanings until at least ~2000rds or whenever the comp has told me it's time lol. I loathe cleaning out the comp, when it gets terrible is when I'll take it on and strip/clean the whole gun. I just keep the bolt wet and the gas end dry and mine have run great.

I leave a box of factory FMJ in my bag and usually crack off 2-3 after an outing or every few hundred rounds as I do think it does blow out some of the crap the coated bullets leave behind. But, I do that more for the barrel than the gas system.

 

FWIW, I think one of the main reasons I've seen MPX's get temperamental due to grime is when guys are running them close to minimum power factor; that, plus dirty gun, no bueno.

[NOSHMJ]

Ive ran thousands of coated bullets thru my MPX, without a single hiccup, or failure.  I run 147 Blues under 4.0 grn of power pistol.  I clean the gun after about 1000 rds.  Scrub the piston and piston chamber clean with a brass brush.  I run my bolt sloppy wet against peoples recommendations, but it has yet to fail.  I do carry spare extractor springs and the little rubber washers with me because they are going to fail.  The thing feels like a shooting a rimfire. 

Edited December 8, 2020 by NOSHMJ

[jnr88]

The MPX needs to run wet.Do not lubricate the gas block!

[Bdh821]

I did a complete tear down of my primary MPX. I think I had maybe 600rds thru it as I haven't been shooting much lately due to winter when shooting essentially comes to a hard stop.  I'm heading to Florida tomorrow for the sectional match.  The gas system even from that amount of rounds still takes a vice to turn the gas plug and a brass hammer to smash the piston out.  Overall, cleaning it was quite simple again with such low round count.  It's just time consuming. I again only lube the metal on metal rubby parts.  I don't run mine what some would call wet anymore.  Especially being a lefty, running it wet would spray oil on my face for the first 50-60 rounds or so.  I make sure to clean behind the extractor during this tear down. 

 

On 12/6/2020 at 1:42 AM, ck1 said:

FWIW, I think one of the main reasons I've seen MPX's get temperamental due to grime is when guys are running them close to minimum power factor; that, plus dirty gun, no bueno.

 

^ I agree with this.  The last match I shot, which it was 38 degrees outside, a fellow MPXer was using 147gr mouse fart ammo at like 128pf... yeah his gun didnt run.. and when it did, the brass was dribbling out of the ejection port.  My brass gets sent like 20'.   He also had to do 2 reshoots as the RO didnt get his last shots.  All of which is another reason I run 115s at 140pf

Edited December 9, 2020 by Bdh821

[NOSHMJ]

I find the MPX, well at least mine, loves the 150+ power factor. 

[Chutist]

I have 5 or 6 hundred though my new MPX and just (like I just washed my hands and sat down...) finished cleaning it for the first time.  Hit it with some gun scrubber, cleaned the bore and and wiped down the bolt assembly.  Sort of interesting the way the spring assembly cam's into the bolt group.  Lubed it all down with one of the Sig "Ketchup packets" of oil.  I was surprised how easy it was to deal with and how smooth the bolt worked after a good clean and lube!  It was "cleaning day" did my AR, Sig 365, Sig P320 CO gun and the MPX.  The one packet of oil was enough for all! 

 

So far it's run everything without a hiccup - Coated reloads, cheap steel cased stuff and regular factory 9mm.  Giggle every time I shoot it... 

 

I do plan to get a Lula to load mags with! 

[Nolan]

21 hours ago, Chutist said:

I have 5 or 6 hundred though my new MPX and just (like I just washed my hands and sat down...) finished cleaning it for the first time.  Hit it with some gun scrubber, cleaned the bore and and wiped down the bolt assembly.  Sort of interesting the way the spring assembly cam's into the bolt group.  Lubed it all down with one of the Sig "Ketchup packets" of oil.  I was surprised how easy it was to deal with and how smooth the bolt worked after a good clean and lube!  It was "cleaning day" did my AR, Sig 365, Sig P320 CO gun and the MPX.  The one packet of oil was enough for all! 

 

So far it's run everything without a hiccup - Coated reloads, cheap steel cased stuff and regular factory 9mm.  Giggle every time I shoot it... 

 

I do plan to get a Lula to load mags with! 

 

Wait until you discover all the hidden gunk after you think you've gotten it spotless!  For a gas piston gun, it's a dirty critter with lots of hard black crusty build up that really hides in plain sight in the corners and crevices.  I was surprised at the amount of crud on the front of the bolt carrier spring guide where the gas piston pushes, there really is a dished area there under all that hard carbon crud.  The first couple of times I cleaned the gun I thought that area was flat.

 

I've been thinking about 3D printing some block off parts to put into the open spaces at the front of the upper receiver to prevent some of the port gasses from blowing back into the receiver.  That area is always filthy in mine.  Pop the upper off the lower, remove the handguard and look at the open areas around the sides of the gas block and the charging handle slot above that are open back into the upper receiver.

 

Nolan

Edited December 19, 2020 by Nolan