Slam fire woes

[Clint]

So I went to range today to test my the Checkmate mags I just received. The seven rounders I had from the group buy had out a spec feed lips so I sent them back to Checkmate. They came back a few days ago with the lips fixed and with two new, shiny eight round hybrid mags. Off I go to the range with my mags and 100 bullets.

Everything was going so well. Then, I load up my second to last mag full of ammo and press the trigger. The recoil felt bad. Sounded bad too. Then the fear sunk in that I just slam fired my gun. I cleared the gun. I waited a few minutes, maybe I just bump fired it, then shot again. All's fine. Shot again. The hammer followed. The gun is now in conditions two for the first time ever. Things are not looking good. So of course I clear the gun and decide to try again(!). The last four rounds in the mag all come out at once. Three of them (apparently) going into the big hole in the target the previous 40 shots made.

I asked the Gun Store/Range Guy “C” to look at it. He loads one round in the magazine and the gun functions fine. Two rounds in the mag and the gun slam fires again. C comments that the good news is the firearm is durable to take such stress. A new Ed Brown disconnecter later, he shoots it again, by the numbers. One round in the mag, then two, then three. I watch and can see the slide “stutter” in the rear position. It pauses briefly, just long enough to see. Then I shoot it by the numbers and I can feel the slide “stutter” a little but that feeling disappeared with the second three-round-loaded magazine. By now I had bought a new box of ammo. The stutter showed up maybe once or twice more and once the hammer fell to half-cock.

After I clean the gun and check out the parts I am taking the firearm to the gunsmith to have the disconnecter fitted. I bought a STI trigger recently so I'll get that fitted too.

Anyone have any ideas on what else I should be doing. A new sear perhaps?

I used to think MIM was ok, but now... My mag release (MIM) broke a few months ago and now this.


On the bright side, the mags worked fine.

[Hill]

I'd buy a good sear and hammer whether it needs it or not. If your original parts are breaking why wait for the rest to break, even if it proves out that they aren't broken yet.

If you've had recent trigger lightening work done, or overdone, I think a new sear and possibly a hammer is in order also. Sometimes trying to correct a poorly done job just makes it worse. Better to start over.

Several things associated with lightening pull and/or shortening takeup can be done incorrectly and cause going full auto. Especially the case when the sear face and full cock notch are stoned to an altered angle.

[Clint]

No trigger work was done...yet.

[robot1911]

That 'stutter' may be the slide striking the disconnector crown as it tries to return to battery. IF that's the case, you can polish the angled areas on the crown to allow the slide to pass easier, and you can also polish the leading edge of the disconnector rail in the slide(where it contacts the disconnector) and if there's no bevel there, stone one in...just a little, and polish it.
If it is the disconnector causing the stutter, there are other areas that can be causing it as well...like too much leaf spring pressure on the disconnector's paddle.

Bob

[Hill]

No trigger work was done...yet.

What model pistol are you talking about - what brand?

No spring changes either?

Describe what you mean by "stutter".

With: "The last four rounds in the mag all come out at once"
you mean that your pistol fired four rounds in quick successtion for your single pull of it's trigger?

[twin oaks]

If the "stutter" wasn't present before you used the new mags, I suggest comparing function with the old mags. It could be a dimensional conflict with the new mags and the magwell. Check to see where the follower is contacting the slidestop, and whether or not you're getting a little lifting of the SS with the bullet nose (use a dummy round for this, of course).
Anyone know if some tolerance stacking in the magwell could affect the trigger group?
After the kinds of failure you've described, I'd definitly say the hammer and sear need to be inspected WELL if not completely replaced. It kinda sounds like you've sheared off a portion of the hammer hooks.
[pull pin...comment...count to three...] And stay away from MIM parts.

[Clint]

What model pistol are you talking about - what brand?SW1911PD, 5” with the rail.
No spring changes either?Added a 23 lb mainspring and 16 lb recoil spring, but those were a few range sessions ago.
Describe what you mean by "stutter".When the slide does its back-and-forth routine, it stops briefly somewhere in the back position(but I doubt when fully to the rear.)
you mean that your pistol fired four rounds in quick successtion for your single pull of it's trigger? That is the definition of a slam fire.
If the "stutter" wasn't present before you used the new mags, I suggest comparing function with the old mags. Doubtful. The new mags worked when the disconnecter was replaced
After the kinds of failure you've described, I'd definitly say the hammer and sear need to be inspected WELL if not completely replaced. It kinda sounds like you've sheared off a portion of the hammer hooks.The hammer looks fine and (so far) engages well when function tested, but the gunsmith will definitely need to look.

[pull pin...comment...count to three...] And stay away from MIM parts. I don't really have the money right now to be switching all the parts right now.

[John]

Mags have nothing to do with the pistol going full auto.

[David Rose]

Clint, just for clarification... a bullet is the projectile. It cannot "fire" or be fired. A slam fire occurs when the action closes, not when the trigger is pulled. However, I do think that I understand your problem as you describe it.

If you are trying to deal with the problem yourself, look for anything that could cause the sear not to reset before the hammer can fall. This could be many things. The sear spring left and middle finger positions could cause this. Anything that could cause those fingers to not do their job, such as "misplacement" or improper tension could cause it. A bad sear nose or hammer notches could be a problem also. Bad here could simply mean damaged or improperly cut to start with. Another thing that could cause this is a heavy trigger under certain circumstances. In an S.A.M. I just found a trigger which had too long a bow that contributed to this.

If you do not want to deal with any or all of these problems, I think S&W still has a lifetime warranty. I believe that in your position, I would take advantage of it. The shop where you bought it might even ship it back at no cost to you! Or Smith might send a call tag.

At any rate, I would not shoot it until the problem is resolved! This is not a good thing for you or the gun!

David

[Hill]

A slam fire is one where a chambered cartridge is fired by inertia to the firing pin when the bolt/slide "slams" closed. It has nothing to do with a trigger or disconnector malfunction.

[Pappy]

As a side note, you have an illegal machine gun.

Probably not a serious concern if you are trying to rectify it...

[kcshooter]

A slam fire is one where a chambered cartridge is fired by inertia to the firing pin when the bolt/slide "slams" closed. It has nothing to do with a trigger or disconnector malfunction.Right, you had an unintentional full-auto episode. Slam fire is different. This does sound like a sear/hammer engagement problem. One or both parts will most likely need replaced.

It could be a few things so I agree with sending it into S&W, call them and they'll even pay the shipping.

Also, you had a MIM magazine release break? Where on the part did the break happen?

[Clint]

OK, I thought a slam fire was when the gun fired a round as soon as the action closed, regardless of trigger involvement.

The good news is I had a smith look at the gun today. Yesterday, I had a new disconnector put in. Today it was fitted. The hammer appeared fine to everyone who looked at it. The sear's contact surface was cleaned up (polished) and coupled with the new STI trigger (also fitted today) the gun has a nice clean trigger pull of about four pounds. A little more take up than before but with NO creep. :D

I shot 25 bullets today with the new setup. I'll see if I can do more tomorrow, but so far she's better than new.

And IF anything else goes wrong I'll be sending it S&W to have several of the internals replaced. My brother said if he spent $800-$900 on a gun that did this stuff he would be "mad". I guess I should be, but I'm just glad my gun is working again.

[Clint]

Also, you had a MIM magazine release break? Where on the part did the break happen?Specifically, it was the “Magazine Catch Lock” that broke.

#21 on this Schematic:
http://www.brownells.com/aspx/ns/schematics/schemmfg.aspx?schemid=141&m=3&mn=Colt%c2%ae&model=1911+Government+Models+#20

The little tab that locks it in place sheared off during a rare use of an outdoor range. The whole Magazine Catch Assembly was replaced as I didn't like the extended mag release on a carry gun anyway.