New Sig 220ST--did I already screw it up?

[SubSolar]

So picked up my brand new 220ST with external extractor yesterday and hit the range today. From the first target, I knew this was the most accurate gun I've ever fired. Here's the first target @ 7 yards.



Anyway, here's what happened. First 50 rounds, flawless. I decided to try my Federal HST 230 grain +P's that I plan to use as my defense load. First shot felt like a dud, puff of smoke but didn't see any hole on the paper. Recoil felt like a .22. Didn't eject properly so I cleared it and fired again. Same thing although this time there was a hole on the paper, albeit very low from point of aim. This is when I realized just how big of an idiot I had been. I had also brought my 226ST in .40 S&W because I hadn't tested it with the Federal HST's yet. I had accidentally loaded the 220 mag with .40 S&W's! Here's some pictures of one of the shells.





It looks like it bulged and ripped apart. I could not believe that I did this. I've taken multiples guns with multiple calibers to the range before and never been this dumb. Why couldn't I have done this to one of my Glocks instead of my brand new 220ST? Anyway, this is when some problems started happening. I loaded it with the proper .45 HST's and it failed to fire one of them in the magazine. For the next hundred or so rounds it would also fail to fire ocassionally even with regular Blazer Brass. When it did it was only once per magazine (always some round in the middle). I had about 3 failures to fire. The round before would fire fine and eject but then on the malfunction I'd pull the trigger and nothing would happen. Then I'd rack the slide and the round would come out looking like new. Then everything seemed okay for about 50-100 rounds (except my friend had some sort of malfunction on the first round, but I think he may have not loaded it properly or limp wristed). The range was closing so I went home.

At home I cleaned and inspected the gun. I didn't see any damage but I'm far from a gunsmith. Barrel looked fine. Not feeling satisfied, I packed up and headed to another range that closes later. During this session I fired about 200 rounds without a hitch (WWB and Blazer Brass). This restored my confidence, however I want a few more hundred rounds before I feel comfortable with it.

My questions are, did firing two .40 rounds through it damage it and cause the malfunctions? Will problems show up later because of this? The first 50 rounds were flawless before I did that incredibly stupid act. However, the last 250-300 rounds that I have put through it have also been flawless. Did the gun or magazines just need some break-in? It seems weird to me that if putting the wrong rounds through it would screw it up, it would somehow fix itself later. I'm leaning towards it needing break-in and it just a coincidence that it malfunctioned only after I put the .40's through it but I'm not sure and want some expert advice from the gun gurus here.

Here are some pics and targets.

 

[Thernlund]

It's unlikely that you hurt the gun by doing what you did. Although, it wasn't good to do that.

Here's my best guess...

Being that the rounds you fired were smaller than the chamber, obviously they don't seal the chamber and the gasses are allowed to go around the shell. This is common sense obviously. What may have happened is that, due to the gasses and gunk going everywhere in the chamber, that gunk mucked up the firing pin channel preventing the firing pin from moving freely in the channel. It took awhile for the muck to get pushed aside and partially cleaned out by subsequent firings.

Once the muck was gone and out of the way of the firing pin, reliability was restored.

That make sense?

Be sure to carefully inspect the chamber. If all looks good, I expect, assuming you always fire the right ammo, everything will be fine.


-T.

 

[SubSolar]

Being that the rounds you fired were smaller than the chamber, obviously they don't seal the chamber and allow gasses to go around the shell. This is common sense obviously. What may have happened is that, due to the gasses and gunk going everywhere in the chamber, that gunk mucked up the firing pin channel preventing the firing pin from moving freely in the channel. It took awhile for the muck to get pushed aside and partially cleaned out by subsequent firings.

Once the muck was gone and out of the way of the firing pin, reliability was restored.

Yeah, actually my friend's Dad who is very knowledgeable said it was blowback. He suggested a detail strip, do you think that's necessary if it continues to be reliable?

 

[Thernlund]

Can't hurt. Even if it happenes once in a 1000 rounds, that's once to many times, eh?


-T.

 

[Sylvan-Forge]

Good analysis, Thernlund.

Nice piece and nice shooting, SubSolar.
Detail stripping the P220 isn't very easy. You'll need cup tip punches and a very solid, non-springing surface to secure the slide to in order to remove the press-fit pin that retains the firing pin.

You could try blasting some cleaner or lube into the FP channel. Try from the rear, near the FP while pressing the FP in with something. Move fore, shooting into the FP block safety. Let it sit muzzle down.
After a spell, keep the muzzle pointed down and do some dry firing.
Finally, give a good blast into the FP breech hole. Repeat.

If you get a light strike/no-strike again, there is probably a piece of brass in there which will mean a detail strip or sending it off to SiG or a SiG Armorer.

Best o' luck.

PS. I wouldn't worry about the gun being damaged per se. Those are some solid hammer-forged barrels. Tougher than nails.

.

 

[Disaster]

Echo the call for a good cleaning. Don't think a full strip is necessary. First try flushing it out real well. Also, look for bits of brass that may have migrated to places where they could be causing the issue. Most likely it is just lots of gunky half burnt powder that is causing the problem.

 

[SubSolar]

I think Thernlund is right. Also, the field strip and cleaning between sessions probably cleared things out too. How exactly can I more thoroughly clean the firing pin channel without a full detail strip? Some sort of compressed air or spray some CLP out of a can? For cleaning I usually use WeaponShield and a toothbrush.

 

[RPCVYemen]

First shot felt like a dud, puff of smoke but didn't see any hole on the paper. Recoil felt like a .22. Didn't eject properly so I cleared it and fired again.

This strikes me as an extremely dangerous course of action. A squib that left a bullet lodged in the barrel would have had very low recoil, would have had trouble ejecting, and would have mad no hole in the paper. But the next round would have found an obstructed barrel. That might have been a tad more fun than you really wanted.

If a round doesn't go off at all, then I don't hesitate to pull the trigger again. But if the round does go off, and something's wrong with the recoil you don't see the bullet hit the paper, I wouldn't fire another round until I knew the bore was clear. But maybe I am just paranoid ...

Mike

 

[SubSolar]

No, you're right.

On the positive side, I didn't seem to have any extractor issues such as malfunctions on the last round of the magazine. And I even got complimented by the guy next to me who said "how do you get your groups that tight?" He was a former Marine headed to Louisiana to help in the relief effort. He had a Glock 17 rental, which he needed to qualify with in a few days. I told him it wasn't me, it's the gun.