FTFs

[jambie]

My MarkIII is experiencing an abnormal number of FTFs
I have changed the firing pin but that did not help.
Looking at the spent shells, the show very light firing pin strikes.

I now suspect that the hammer spring or hammer spring plunger may be damaged.

I have not attempted to take the spring or plunger out for examination.

Any words of wisdom on how to do this?

Thanks

[toyfj40]

My MarkIII is experiencing an abnormal number of FtFs
I have changed the firing pin but that did not help.
Looking at the spent shells, the show very light firing pin strikes.

I now suspect that the hammer spring or hammer spring plunger may be damaged.

I have not attempted to take the spring or plunger out for examination.

... from your description, your FtF is 'Fail to Fire', right? (not Fail-to-Feed)
Which model(mk3 -or- 22/45), barrel?
How many is Abnormal?
What brand(s) of ammo?
How long have you had the pistol(time/shots)? Did it usta-work, now failing?
Did you get it at a GunShop, with a GunSmith that might be able to help?
Do you have other MKs (to compare to)?

Does the Hammer-Strut appear to be rubbed, such that it might be
mis-aligned/forced down into the mainspring-housing... ?
(can you compare to another for burrs or indications?)
(I don't think you want to consider opening the MainSpring,
just press down with a small pin-punch to get a "feel") is it lubed?

Could anything (crud?) be holding the bolt-face back from the chamber?
that could increase the HeadSpace and result in Strike-Lites.

Does your firingPin easily run Fwd/back in its groove?
Is it clean underneath it, is the little underneath return-spring/guide
aligned/seated properly?

Does a cartridge easily "drop-in" and "fall-out" of the chamber?
indicating no restriction to an easy/full chambering?

Check the ScopeRail-screws that they do NOT penetrate into the receiver
and drag on the Bolt. (or the filler-screws, if no rail used).

This should be enough "first aid", there will be other ideas coming soon.

[Bullseye]

Does your firingPin easily run Fwd/back in its groove?
Is it clean underneath it, is the little underneath return-spring/guide
aligned/seated properly?

I'll second this as the next step. Typically when I start seeing light strikes there's a build-up of crud in the firing pin track. About every 2000-3000 rounds I have to clean mine out to prevent light strikes. It is also wise to check the firing pin return spring and ensure it isn't bent or broken. Sometimes if this spring is damaged it can interfere with the firing pin's travel.

Make sure the chamber is clean or that there's no peening at the top of the chamber mouth where the firing pin strikes. If the cartridge isn't seating fully some of the firing pin's impact will be absorbed by the case rim as the cartridge is being pushed forward agains the chamber mouth. A fully seated cartridge will utilize the firing pin and the chamber mouth to pinch the case rim and detonate the round, like a hammer and anvil.

There is little chance that your mainsping components are damaged and causing this problem. Unless your mainspring housing is warped or extremely dirty, everything should function properly in that mechanism. This would be a last resort. Mainsprings are notoriously challenging to reassemble.

I'd check my hammer to ensure that its travel is unhindered. The front could be dragging on the sear, slowing down the hammer's movement. Or, there could be dragging inside on each side of the hammer which would again slow down the hammer's speed and energy.

Hope this helps.

R,
Bullseye

[jambie]

Thanks for the suggestions as the causes of the fail to fire.
I will take the gun appart later today and, based on your ideas, determine where the cause may lie.
I'll post my findings then.

Again, thanks for all the help.

[jambie]

Thanks guys for all the great suggestions.
Took the gun apart, gave it a good cleaning but nothing seemed out of the ordinary.
The only thing I noticed was a loose barrel. I normally put a couple of aluminum shims along with a trigger guard to afix the barrel (I have a very loose barrel) It is possible that the loose barrel may have changed the geometry of the hammer/pin interface. I added another shim and the barrel is now more solidly affixed. By the way it takes 6 aluminum shims plus the trigger guard to make the set up solid.
I will test the markIII this afternoon and let you know how it worked out.

Thanks again.

[jambie]

Took three kinds of ammo for testing.
American Eagle, red box
PMC sidewinders
CC Green Tag

With the American Eagles, many failure to fire. On one occassion all 10 rounds in the magazine failed to fire.
Examination of the dud rounds showed a very light strike on the rim. Sometimes the dent on the rim was even hard to see!
All total, about 80% failure to fire

The PMC rounds faired better. About 10% duds. Those that failed to fire had very light strikes.

The CCI green tag, all went bang Looking at the spent cartriges showed a nice dent on the rim.

I am still puzzled by the very light strikes with the American Eagles.

Thanks

[bearandoldman]

Took three kinds of ammo for testing.


I am still puzzled by the very light strikes with the American Eagles.

Thanks

Must be veryhard or just thicker brass, also may be a little larger in the case diameter and notseating fully in the chamber.

[Bullseye]

Jambie,

Try giving your LCI a good look. Make sure that it isn't a crudded up and causing the new rounds to fail to seat. If the new cartridges aren't seated fully in the chamber when the firing pin hits the rim instead of denting it, the firing pin's energy will be wasted on seating the case the rest of the way in the chamber. This will leave a very slight dent like you've described.

From your descriptions it sure sounds like seating is the problem, but isolating the source can be tedious.

R,
Bullseye