Caps not going off on first hammerfall

[rcbcm]

I'm having trouble with my Thompson 45 Hawkin setting off the cap on the first hammerfall. I was told I could have the Lock tightened down too much. Anyone else had a problem like this?

 

[Cowboy45j]

Yup, same thing was happening to me with my .45 kentucky rifle. I had the lock too tight. Did you try losening it up yet?

 

[Billnpatti]

There are several reasons why this could be happening. First, check to see that you haven't over tightened the lock screw(s) that hold the lock in the rifle. Next, are the caps in good condition and have they been properly stored? If the caps have been exposed to high humidity or allowed to get damp in a rain, they may not be any good. If you decide that the caps are not the problem, then, they are not getting a good strike from the hammer on the nipple. Check the nipple. Have you or someone else been dry firing your gun with no cap on the nipple? You can hammer the top of the nipple so that the cap does not fit on it properly and will not receive a propper strike from the hammer. If you determine that the nipple is in good condition, the hammer is your next concern. Is the hammer clean in the recess that strikes the cap? Use a toothbrush to get up in there and scrub out any dirt and gunk. Use a toothpick to scratch around up in there to see if an old spent cap is stuck in there in a bunch of crud that has collected in there. If the hammer is nice and clean, next check to see that it is falling freely and not binding somewhere along the side of the lockplate. An easy way to do this is to remove the lock from your gun, remove the hammer and use a candle to smoke the lockplate. Replace the hammer on the lock being careful not to smudge your soot coating. Carefully cock the hamer and use your finger to press on the trigger bar to release the hammer. Keep one finger on the hammer to ease it down to the "fired" position. Do not let if fly forward freely. Do this a couple of times and if it is rubbing on the lockplate, you will see it in the soot coating. If this is occurring, you can make a shim to put behind the hammer to keep it away from the lockplate or you can carefully file the back side of the hammer to give it enough room to operate without hitting the lockplate. If the hammer is not rubbing anywhere on the lockplate, the only thing left is to examine the inside of the lock to see if the tumbler is rubbing on the inside of the lockplate. This can be done initialy by simply carefully examining the lockplate in good light with some magnification. If you see any rubbing or can feel it, you can shim the tumbler so it doesn't rub. If you don't feel comfortable disassembling the lock to work on the inside, you may have to take it to a properly qualified gunsmith to have the work done. Last of all, reassemble your lock and replace it into your gun. Now look for any place that the hammer might be rubbing on the stock.

Once you have done all of this, the problem should be solved. I have never seen a bad spring on a T/C or a Lymon Hawken. Some of the less expensive Hawkens may have springs that go bad and have to be replaced. If you suspect that it is the main spring and it is a flat spring, as opposed to a coil spring, you will need a spring cramp to remove and replace the mainspring. Do not try to do it without a spring cramp or you will likely break the spring. BTW the correct word is CRAMP not clamp. I don't know why, it just is.

Good luck in solving your problem. If this hasn't been as helpful as I hope it is, another one of the folks who answer will have other ideas that could be better than mine.

 

[BenCoogle]

One thing that might do this is undersized caps. The first blow seats it and the next one sets it off. Never had much experience with caplocks though! If the lock bolt is too tight you must have a 'bearing' in the lock mortice. Ben

 

[bwhoffman]

dyr firing can mushroom the top of the nipple as well. you can dress it with a light file or stone while having the nipple chucked into a drill motor.

 

[Wink]

I had the same problem with caps fitting too tight on the nipple. First hammer would seat the nipple next time it would go off. A Rat-tail file to the sides of the nipple took care of the problem. Just a few strokes at a time and dont take off too much.

 

[renovato]

It's most likely from the caps fitting too tight on the nipple. This is a common problem as nipples aren't really standardized in size. Luckily, it's easy to correct though. You can take a file to the nipple to reduce its diameter so that the cap will fit better. You want to be able to seat the cap all the way down on the nipple with finger pressure, but not be so loose that it falls off. You can chuck it in a drill or drill press and lightly touch the file to it, but I just hold it in my fingers and rotate it as I file. It only takes a couple minutes.

 

[necchi]

Why not just check the screws that hold the tumbler in place? Inside the lock is a plate that's held in with two screws. Underneath that plate is a little floppy thing called the "fly detent" (it helps the trigger sear skip past the half-cock saftey position). If those two screws are the tinniest bit loose, that detent thingy will tip and stop the hammer short! It looks like it falls, and it sounds like it falls, but the hammer won't even strike the nipple!
T/C's and Lyman locks are notorious for that. Oh and don't forget to clean and oil the lock every once in awhile. just a single drop on all that "working stuff" under that plate goes a long way's.
good luck

 

[Jblk]

I had the same problem with one of my cap guns.I dressed the nipple, polished the interior of the lock, retempered the main spring all to no avail.The darn thing might fire several times in a row and then mis fire.The mis fire was always when you needed the the thing to go off.I finally heated the hammer and slightly bent it, and my problems ceased.The hammer appeared to be perfectly alligned before I took this action, but aparently it was not.

 

[Birddog6]

My first thought is "Are the caps the correct size?". Should be #11 caps. If they are #10's they will not fit the nipple correctly.

 

[bob308]

i have had this problem crop up on my underhammer. got to looking at it and found the new nipple was over size on the od where the wrench fits. the hammer was catiching on it. just a trip to the lathe and the problem was fixed.

 

[mloader40]

As the rifle is fired over a period of time the nipple will mushroom slightly. The cap will not not slide on completely, to cure this replace the nipple or remove the nipple chuck the threaded end carefully in an electric drille motor. Use the drill as a lathe and reduce and chamfer the nipple with a file until the cap can be easily installed. I have used this technique many times and it alwas solves the problem.

 

[R.M.]

Yup, a little work with a file, and I do mean little, will do wonders.
One thing I've never seen mentioned here is, you can put a nut on the threads and chuck the nut in the drill chuck. This will prevent any possible damage to the threads. Some may say not to chamfer the edge, but I've had good luck with a small radius.
Also as previously stated, a new nipple is a cheap alternative.

 

[THBailey]

Had the same problem with my Pedersoli 12ga. I was not getting the caps snug down on the nipples. Now after I cap I softly set the hammer down and push on the back of the hammer to snug down the caps. Have not had a problem since adopting this protocol, but needless to say be absolutly sure the gun is pointed in a safe direction when seating the caps. I have not had an unintentional discharge, but it sure could happen.