I just bought a used SW4566 from a local shop. The exterior is in perfect shape - not a scratch on it. It is set up like a LE issue with decock only lever. I fired a box of 50 and it misfired on 6! I took it back to the shop and they told me to clean it well and try again. I told them to keep it and have the gunsmith check it out before I fire it again. Should I be concerned over this malfunction or is it soimething the gunsmith should be able to correct? The pin marks on the misfires were slightly off center. Also, the barrel is slightly loose with the slide back.

By misfired it chambered the round just fine but went click? Was the slide fully forward? No failures to feed or extract (except for the ones that went click)?

Any time I purchase a new (to me) firearm I strip, inspect, clean as neccesary, and check for function before I put any live round in it.

Where the firing pin marks on the others dead center?

Yes, it chambered the round and went click. No other feed or extraction issues and unfortunately I did not save any of the casings from the fired rounds. The gun shop cleaned and inspected the pistol before they sold it.

A gunsmith should definately be able to correct the problem. If this were a carry weapon, I'd worry about the malfunction. I wouldn't want it going click instead of bang.

The gun shop may not have cleaned it thoroughly if they suggested you clean it well.

Do you have a few magazines? Happen with all of them? It could be as simple as a worn out recoil spring or a bunch of gunk in the firing pin channel.

I ordered a new magazine and a new recoil spring. After the gunsmith works on it I will give it another cleaning and try again. Thanks for the info.

You might consider a new hammer spring, if you are getting light primer strikes.

But first, if it was my pistol, I would clean it thoroughly. I would buy a can of nonchlorinated automotive brake cleaner, and spray the firing pin channel thoroughly. Then oil the area lightly with a good quality gun oil.

If it's dirty in there, that would cause the light primer strikes.

I had that happen tome once with my old Model 59. I was firing cast lead slug reloads, and the bullet lube gummed up the firing pin.

Odds are, given that the pistol is in such good condition, it's something simple.

Good luck with your new S&W pistol!

Do you trust the gun shop? The 4566 is one of the most reliable handguns around and it should hit the primers hard. I would also vote for a good cleaning, and inspection by a gunsmith. It is probably just in need of a good cleaning and lube job. I have run across a few guns over the years that wouldn't fire properly and upon disassembly found them clogged with goo-probable suspect WD40. Could be that a shady tree gunsmith might have fooled around with the hammer spring causing light primer strikes. It should be leaving a respectable dent in those primers. You did the right thing taking it back to the shop-make sure you talk to the gunsmith who looks at it to get the straight story on what was going on with the gun. If somebody was fooling around with the innards you want it made right before you think about using it for defense.

Sounds like it did not go into full battery,out just enough to cause a light strike. If you have this problem again take a quick look after each shot and make sure the slide goes forward all the way. (new recoil spring should help here).

Try different ammo as well.

The barrell should have a little wiggle room with the slide to the rear.

__________________
SC Army National Guard

I'd also remove the firing pin and spring and clean the firing pin channel. Alot of gunk can build up in there. Good luck. Regards 18DAI.

At what point in the magazine did the misfire occur and was that consistant through-out the 50 rounds?

I was only loading 5 rounds at a time in the magazine and at least half misfired as the first round fed

This sounds more like you're riding the slide forward instead of dropping it from being locked back or pulling it all the way to the rear and letting it go, under full force. That will definately cause a mis-fire

+1 never ride the slide. Unless your at the water park

__________________
SC Army National Guard

I just picked up the pistol from the gunsmith. He felt the misfires (I brought them in with the pistol) were light strikes and he replaced the hammer spring along with a thorough cleaning of the firing pin area. He said it test fired OK with a assortment of ammo. I will probably still replace the recoil spring. Thanks for all the suggestions. I was able to intelligently talk about the repair as a result and am confident the gun was a good buy.

What type of ammo were you using?

Fiocchi FMJ

Well, I was going to say that if it had been brought to me by one of our folks, being an older model 4566 I would've first looked at the condition of the firing pin channel (for cleanliness).

I've seen any number of light-strike conditions result from an accumulation of excessive solvent/CLP getting inside that area and congealing into gunk. Once it became heavy enough it could start to interfere with the freedom of movement of the firing pin, including becoming lodged between the coils of the firing pin spring and slowing compression of the spring. This area ought to remain dry and free of solvent/oils, but when some folks apply an excessive amount to their slides during cleaning it seeps inside that channel it can't easily run back out.

Checking for damage to the firing pin tip, or firing pin spring (damaged/broken coils), would've been something to check, too.

I would've also considered the potential for hard primers (especially with foreign ammunition), a damaged main (hammer) spring (or stirrup), as well as checking to see if someone had removed the grip pin (which supports the mainspring cup).

I'd have also checked for a weakened (shortened) recoil spring. Being a used gun, it wouldn't be a bad idea to replace the recoil & magazine springs just for preventive maintenance. Probably the black mag followers, too, especially if the raised spot on the top of the followers has been worn through. This raised dimple helps keep the last round from being displaced under recoil when the mag spring is at its least amount of tension, you know.

Glad the gunsmith got your gun up and running.

__________________
Ret LE Firearms inst & armorer