Mis-fires

[Hoot-3rd Ga]

Gentlemen:  I've encountered a new issue with my Armisport Spencer carbine. After running thousands of rounds through it (I love to shoot it), it has started misfiring on average one out of every 15 or 20 rounds. At first I thought it was just a bad batch of primers (I use federal #215 large rifle magnum primers and black powder). Upon closer examination. I discovered that the firing pin hole in the upper block was slowly but surely closing up. I have one of the older color case hardened block assemblies. Apparently the metal around the firing pin hole was starting to compress inward.  I ordered a new one ($50+). It showed up as one of the blued steel upper blocks. I am told that they can be hardened better than one that is only casehardened. If that is true, this new replacement should last a lot longer than the first one. It may help explain why Armisport changed over from the colorcased to blued steel.  I will be testing this theory this weekend at a N-SSA skirmish.    Hoot - 3rd Ga

[Fox Creek Kid]

Hoot, I have one of the early ones & it peened a little, BUT what caused my misfires was the fact that the firing pin slide screws were working loose causing light hits. Two drops of Loctite and cured! If mine peens to the point of non-function I'll have a buddy machine in a recoil plate on the breech block face.

[Injun Ryder]

Expanding upon FCK's reply, I had a similar problem with the screws but that also caused the slot in the percussion plate to be peened a little so that it did not fit tightly in the tab in the firing pin pusher (which was also peened, though to a lesser degree). I ordered a new percussion plate, smoothed out the pusher and loctited the screws after assembly. This has solved the problem thus far but I have not shot it extensively since I performed this repair.

[Dakota Widowmaker]

Well, I am only getting about 1 out of 3 hits on a Winchester Large Rifle Magnum primer to work.

Here is a crappy pic.


I buffed and cleaned up the striker plate and tightened the screws. Thats not it.

The top of the mainspring is untouched... I only thinned out the bottom. (for the trigger)

My misfires started BEFORE the spring was touched.

Suggestions???

How would peening the face of the breach block help??? What tools does one need?

I have a new firing pin on order as well, but, I was hoping to have this fixed up before this weekend.

When my spencer was new, I didn't have this problem. (some 500 rounds ago)

[Fox Creek Kid]

Do you clean the primer pockets & if so how? If you have not used a primer pocket uniformer then maybe the little spring behind the firing pin has gone bad. Replace it.

How would peening the face of the breach block help??? What tools does one need?

You misunderstood this. Peening is a BAD thing. Is there peening on the breech block face around the firing pin hole? You do NOT want this to happen. Primers should seat approx. 0.003 below the level of the cartridge head face.

Eliminating that your firing pin hasn't shrank (I hear that happens with fellas your age  ) the problem is IMO either:

A. Primer pockets have been uniformed too deep.

B. Seating primers too deep, i.e. "crushing" primers when seating.

C. Firing pin spring gone bad.

D. Firing pin slide loose & causing light hits.

E. You're "limp wristing" it. 


P.S. Answer E is a joke. 

[Dakota Widowmaker]

Well, I solved the problem...

The firing pin block (the block that the slide attaches to) was peening.

I measures that I was off at least 0.025" at the breech face with the firing pin hitting light.

I trued up the block, took a thin piece of steel that was 0.025" thick and trimmed it to fit the face of it. Then, I used JB Quick to glue it in place.

I reassembled it all, cap'd 10 pieces of brass and fired them all one by one.

SOLID IGNITION EACH TIME!!!

Tore it all down, the shim was still held in place as I had expected, and then used loctite on the screws when I reassembled the firing block.

So, my trigger is now under 10lbs of pull (about 8lbs from what I can see) and the action is smooth and the firing pin issue is all fixed.

One last time to sight in this weekend and then off to hunt deer.