Percussion problem

[Gametracker]

I have a .54 GPR percussion that I haven't had five months and have only shot a half dozen sessions with. For whatever reason, today it began exploding the caps only on every other cock of the hammer, as if the hammer isn't falling far enough to strike the cap. It does this whether I use the set trigger or not. I've tried pulling the hammer back pretty firmly, but still the same, only every other cap goes off. I hope this can be fixed permanantly instead of happening again just whenever. How can I fix this?

 

[roundball]

I have a .54 GPR percussion that I haven't had five months and have only shot a half dozen sessions with. For whatever reason, today it began exploding the caps only on every other cock of the hammer, as if the hammer isn't falling far enough to strike the cap. It does this whether I use the set trigger or not. I've tried pulling the hammer back pretty firmly, but still the same, only every other cap goes off. I hope this can be fixed permanantly instead of happening again just whenever. How can I fix this?

A couple things come to mind, assuming you're using the same brand of caps and the caps themselves haven't gotten damp, etc:

1) Enough have hammer drops on the nipple have now occurred that the end of the nipple is beginning to get ever so slightly enlarged, and to seat a cap fully, requires more finger pressure now than you've gotten used to using; The first hammer drop finishes seating it, then the next hammer drop fires it off;

2) A used cap has been perfectly expanded up inside the hammer cup and it's still caught up in there, deadening the blows of the hammer on the caps;

Probably a dozen possibilities but these are two that I've personally experienced

 

[crockett]

You could have a damaged nipple, try a new, top of the line nipple. If that doesn't work, did you fool around with the lock( i.e. how fast and hard is the hammer falling. If the inner parts are rough, out of line, etc- could be the problem. Short hammer? Ink up the inside, drop the hammer and wipe the nipple- any ink( fast test)

 

[Zonie]

I just went down this road with my New, Used, GPR.
The other posts all may be right, but here's something else to try:

Pull the hammer to full cock.

Put your thumb on the hammer spur to keep it from falling fast and pull the front trigger just enough to release the hammer.

Just as soon as the hammer starts to move down, release the trigger and slowly let the hammer fall, using your thumb to control it.

It should fall all the way down until it is resting on the nipple.

There is a chanch that it will stop at the Half Cock position. If this is the case, read on. If the hammer falls smoothly all the way down to the nipple, your gun passed my test.

If the hammer stops in the half cock notch, the culprit may be the fly. It may have broken or it may have been left out of the lock by someone.

After using the trigger to release the hammer to the down position, remove the lock and follow this link:
ZONIES FLY FIX

 

[Rebel]

"ZONIES FLY FIX"

Naw, i ain't even goin' there. :crackup:

 

[The Baron]

Did you switch caps? Once upon a time I had the same problem, then found out I had bought #10 caps instead of #11 caps.

 

[BrownBear]

Another possibility: Pull the side plate and make sure all the visible screws are sinched down tight. There's a little black "plate" in there held down by two screws- don't know what else to call it. Anyway, the screws backed out on mine a couple of turns and all heck broke loose, mostly misfires such as yours.

 

[roundball]

Another possibility: Pull the side plate and make sure all the visible screws are sinched down tight. There's a little black "plate" in there held down by two screws- don't know what else to call it. Anyway, the screws backed out on mine a couple of turns and all heck broke loose, mostly misfires such as yours.

Good point...the "Bridle Plate"...I've had that happen too...(put the screws back with a half drop of loctite)...the fly can float out and not operate properly, etc...

 

[hobbles]

I was havin the same problem, When the misfired happened I recocked the weapon and it went off the 2nd time,, bought different brand caps and no more miss fires, ,,
I Have 5 boxs of caps for sale, The old ones,,,,

 

[Runner]

The first and most common problem that causes this is TV shooting. The end of the nipple gets bent out of shape and a cap doesn't seat properly. Sanding the nipple back down will cure that. The second is used cap material building up in the hammer nose. Clean the hammer nose. The third is hammer nipple alignment. If the hammer is not hitting center on the cap, the skirt may be hitting the side of the cap before it comes down on the nipple. This can slow the hammer strike enough to make ignition less than reliable. If the hammer face is not striking flush on the nipple, only part of the cap is being struck. The fourth is the wrong size cap. There are some 10.5's out there being sold as #11's. The first strike drives the caps on and the second ignites them. The fifth is a weak lock spring not dropping the hammer hard enough. The lock mortise being too shallow and the spring dragging on the wood can act the same way.

About a year back there was a batch of caps that came thru thru that could not be depended on at all on the line. They messed up in mulitiple guns everytime they were used at a shoot. If you got some of them, throw them away.

 

[Old40Rod]

Assuming everything is lining up ok... the nipple is probably the easiest variable to fix/check. I had to take a file to my .50 GPR factory nipple as I found that the caps just weren't seating very well. If it is the nipple they will usually go off on the second hammer drop... I shortened and beveled the outside lip of the nipple a bit and haven't had a problem since.

Oh, another thing... make sure you are using #11s. I borrowed a can of caps from a friend, had a heck of a time with them until I looked and did a big "DOH!"... they were #10s.

:crackup:

 

[mowolf]

I believe that rifle has a coil spring similar to the TC Hawken and Investarms. I had the same issue last year with my Investarms Hawken, got a new coil spring and replaced the old one, no more problems. I tried the new nipple, sanded nipple, alignment all the other suggestions. All helped for a while, but the problem would come back. So I replaced the coil and Eureka! Problem fixed and an 8 pointer on the ground in November.

Waya :m2c:

 

[Smokin6Gun]

How old and what kind of caps are you using?
And I am presuming you removed cleaned and lubed the Lock assy. If not try it.

 

[peter]

Gametracker, I had the same problem with my GPR , I looked into the hammer nose and it looked clean,. Then I took an old pocket sized screwdriver and scraped the recess in the hammer nose and was amazed at the amount of residue that came out. I dont remember what brand of caps I was using, but I now scrape the inside of hammer nose every time I clean the gun, and have not had that problem again.

 

[Walker357]

Usta know this gal was scared to death of flys. Til she
opened one up. :nono:

 

[Gametracker]

Now that I dug this thread from its grave, here's an update.
I finally got a chance to shoot today, now that I've got a cleaning ramrod to replace the one I broke. I filed around the nipple, which solved the problem for a while, then it happened again after several unhindered shots. So I filed some more, and, no problem the rest of the shoot. I always clean the junk from under the hammer, so I knew that wasn't the trouble. I guess I should expect the nipple expansion to reoccur now and then? I sure hope I got it fixed once and for ever.

 

[Spring]

I bought a GPR NIB. I had a heck of a time with misfires. It soon became clear that the nipple was oversize and so the caps did not seat properly. Instead of machining it down I found properly sized Thompson Center nipples that work just fine.

Cheers!

 

[strongarm]

Nope, I replace my nipples about once a year. Just like changing batteries in the smoke alarm.