Hey gents, I was hoping to get some assistant from you Sig rifle gurus since this is my first Sig rifle and I know nothing about it.

Back in 2015-2016 (I think), I bought an 8” MPX Pistol.  I bought a bunch of mags, put a tri-lug on it, threw it in the safe and sent off a form one to SBR it, and it’s been in the safe ever since.

Last week went to pull it out, started looking online and realize I have a Gen 1 which seems to be unsupported.  Well I don’t like having an unsupported rifle and would like to update it.

So my question is, how does a Gen 1 become a Gen 2?  Do I need a whole new upper?  Do I just change the current 9mm barrel with a gen 2 barrel?  Is it even possible to upgrade generations without buying a new entire rifle?

Pretty much everything I can find on this is dated information, back when Sig said they would continue to support Gen One which seems to not be the case.  Any help would be appreciated.

Thanks.

Hi Op,

I'm in the same boat. I spoke with a Sig rep a couple of years ago at the NRAAM. Per that rep (and their website) they will put you into a Gen 2 upper on your Gen 1 lower.

I just cut and pasted this from the Sig website:

Are MPX Gen I and Gen II magazines interchangeable?
SIG SAUER does not recommend using Gen I MPX mags in a Gen 2 MPX or vice versa as you may run into functional issues. Please see our explanation and answers to generational differences in the MPX. (The link goes to a dead YouTube page).

I have a Gen I MPX. Will I be able to convert it to other calibers?
Yes, we will offer customers with a Gen I MPX the opportunity to buy a different caliber Gen II upper for the same price as a caliber exchange kit once they are available. We will need to verify your serial number first. You can do so by contacting Customer Service at (603) 610-3000, option 1.

Your best bet would be to call Sig and ask them. I think they will want your serial number, so have that ready. I want to say a Gen 2 upper was around $400 or $600 back when I asked about it. I didn't bite then. My Gen 1 is fine as is.

Please post up what you find out.

Good luck.

I have a gen2 mpx and run gen 1 mpx mags all day long. Don't listen to sigs crap about gen 1 mags not working properly in gen 2 mpx. Never had a malfunction.

Now I could be wrong but I believe SIG gen2 propaganda SCHEME on gen 2 mpx to offer multiple caliber conversions was just that propaganda to sell a gen2 model.

Because I've never seen any conversion kits to 357 SIG or 40 cal

I know some guys bought kits for their gen1 mpx so they could use conversion 357 SIG or 40 cal kits. I'd be really ticked off if I were them.

Have you looked for an 8 inch conversion barrel lately. Just courious.

WHAT I'd do is go to ILWT and see what kind of gen1 barrels they offer. I have one of the 4.5 in barrels from them with a threaded barrel and tri lug milled right on the barrel plus they have all kinds of mpx parts also.

But if I were you. I'd stick with the gen1 they had some issues with the gen2 models in the beginning. People spoke highly of the gen1 mpx.

I ended up buying a gen 2 K upper on gunbroker to also use on my general 1 gun.  Down the road, I'm hoping to buy spare parts kits for both uppers from In Lead We Trust.

Sell your Gen 1 uppers to those of us still running the platform

Also IMO going to Gen 2 is not an upgrade.

2x Gen 1 sbr owner here (bought after Gen 2's were released). Should save your money and buy the new PCC model. Lots of actual upgrades.

Nothing wrong with Gen I guns. mine runs both gen 1 and 2 mags. If it ever breaks I’m sure SIG will fix it and if they can’t I’ll expect them to upgrade it to current revision parts at their expense. Lifetime warranties be like that.

I’m kinda like OP. I bought my Gen 1 pistol right when they came out. Form 1ed it and cut the barrel down to 4” or 4.5” with a 3 lug mount. Eventually bought a ton of Gen 1 mags and added a 4.5” Midwest Industries hand guard.  Just learned they stopped supporting it. I probably only have 200 rounds through it so I’m not worried about wearing it out anytime soon but it kinda made me want to take it off the registry and sell it as a pistol again. I have a lot money in this thing so it makes me kinda sad they stopped supporting it. It’s been flawless but the last thing I want to do is spend a ton of money on a Gen 2 upper and mags.

Anybody with any insight on what one of these are worth anymore?

What would be the first thing to break, firing pin or extractor? Are they the same in Gen 1 and 2?

again, people keep saying "stop supporting it" it has a lifetime warranty, they work with both generations of magazines, what do you mean it isn't supported?

when gen 1 mags dried up I bought a couple of Gen 2, they worked perfectly, I have like 8 gen 2 mags now and they all work. If it breaks, I'm 100% certain SIG would fix it. If they don't have the Gen 1 parts to fix it, I'm also 100% certain, they would slap a Gen 2 upper on it and call it a day.

That makes me happy to know then.