My Gen II #18833 MPX firing pin tip broke off at round #2396 today.  In reading the online MPX manual to get SIG's phone number, I noticed they show a firing pin spring.  My MPX did not have that part.  Was it left out of my MPX and should have been there or did SIG not always have a firing pin spring in the earlier MPX's and thus I may need a new BCG that can use the firing pin spring?

Thanks for the help.

I'll call SIG in the morning.

Edited to add:  Found via search that some Gen II's did not come with a firing pin spring.  Apparently to use a firing pin spring I'll probably need a new bolt carrier.

My MPX is an early Gen 2 and does not have a firing pin spring.

My Gen 2 firing pin w/o the spring broke around 12k rounds, and so did my friend's.  When we called Sig, they sent us a new firing pin w/spring and an updated bolt to install for free.

My gen 2 came with the firing pin spring and backup irons. Pretty sure the new ones don’t come with iron sights or as Sig calls it “optics ready”.

Mine came with spring and no irons. Sig can't really seem to stick to anything. If you get sick of chasing down Sig for parts in lead we trust makes some replacements.

My gen 2 MPX also did not come with a firing pin spring.
The tip of the firing pin broke off around round 300, I called Sig and it took them a almost 2 months but they sent me a new bolt carrier, firing pin and firing pin spring.

Was told I have an early Gen II without FP spring.  Said I had to return the whole MPX.  Was told they'd go over it and install new bolt carrier, FP, and FP spring and pay the shipping.  Pistol shipped back yesterday.  Pain in butt to return, as I had to remove my optic, after market brace, take out my LaRue MBT, and reinstall factory trigger group.  Oh well.

I have a Gen 2 MPX and my firing pin just broke too! Mine is between 3k-4k rounds. Why the hell are all of our firing pins breaking?! This issue seems very common with this platform. Luckily, I noticed a while ago during disassembly that the firing pin had no spring, so I called Sig and they ended up sending me the updated hardware preemptively. I was really hoping I wouldn't have to drop in the updated carrier or "carriage," not sure what they were calling it. If I have another failure at a similar or lower round count once the new hardware is installed I will be very disappointed. Until then, I'll give Sig the benefit of the doubt.

Anyone and everyone who is having this issue or similar issues please post here so we can compile some data and figure out how pervasive this issue is.

Mine had the tip broke off.  I had a local guy look at it.  He felt maybe improper heat treating as where it broke it appeared to be brittle, as opposed to a clean break or cut or bend.

An after market company is making replacement firing pins, but for Gen II they only fit guns that were designed for the firing pin spring style, but then per SIG I'll now have that style when mine is repaired.  After market MPX firing pins

MPX shipped Monday of this last week and received by SIG Wednesday.  Tracking info sent this morning indicates it will arrive this coming Tuesday.  Fast turn around, but then the fix was easy if they had the parts in stock.

MPX shipped to SIG last Monday.  MPX delivered back to me today (Monday).  Just test fired it in the yard, and it functioned fine.  Put back in/on my aftermarket brace, optic, and LaRue trigger group.

Paperwork says, "Inspected the pistol, replaced the bolt carrier, firing pin and spring, extractor spring and gas valve, test fired with no malfunctions."

No idea why extractor spring and gas valve were replaced, but new parts are fine with me.  Will probably re-sight it in this afternoon.  I'll also be ordering an aftermarket firing pin and spring to keep on hand.