Nipple not firing cap on first shot

[hortonstn]

Shooting a underhammer action, cap fires on second drop "11 cap new nipple, tried several brands of
Caps if I file down nipple diameter cap fires but won't stay on nipple  is there a problem with nipples or caps  quality?? Ideas please
Paul

[smokinbuck]

Sounds like you may have #10 caps and a #11
Nipple.
Mark

[smylee grouch]

Make sure you squeeze cap just enough to allow it to stay on nipple.

[Gun_Nut_73]

Just a WAG on my part:  The cap may not be seating fully on the nipple.  The first hammer strike seats the nipple, and the second hammer strike sets it off.

I have a couple of UH, and I need to squeeze the skirts a little to get the caps to stay in place.  If I leave the caps loose, they either fall off, or fail to ignite the first time, like yours.

[hortonstn]

I'm using new 11 caps (Cci and Remington) also new 11 nipples??

[rich pierce]

Common situation.  Dang things are not sized right.  One can use the hammer to press the cap into place, understanding the possibility of the gun firing.  It understandably makes range officers nervous, so be pointing downrange.

[frizzen3]

On my wife's mule ear , the hammer was stopped by the fence  .   A few strokes of  a file  backside of the cup provided enough clearance, fires every time, now. ( a spot of bluing , 44-40 )  and then a drop of oil    CJS

[smylee grouch]

Also make sure the hammer is hitting the cap in the center of the cup. If it hits the cap towards the side it will not transfer all it's energy to the right place. If it is hitting off center you might be able to open up the cup a couple of thousands to fix it or rotate the barrel just a tad to get a center strike.

[Bob Roller]

I would think IF the cap stayed in place and didn't fire then the cap is a dud or the mainspring
hasn't got the wallop needed to fire the thing.I made up an UH for a friend and it went off like a cannon every time
but it had a fast mainspring driving the hammer.

Bob Roller

[rich pierce]

Some nipples are so tapered (flared) they do not allow the cap to seat all the way down. Then the first strike seats it and the second fires it. Solution is to file or grind it but then if overdone caps are loose. Hence the bending of the cap suggestions. I am not sure caplocks are an improvement. I’m not that good with those little doobers.

[Semisane]

Try this. Put the cap on the nipple. Then use a small piece of wood or the ball of your short starter to push the cap tightly down on the nipple. Then, if the cap fires on the first strike every time you know the problem is cap/nipple fit. If it still does not fire first strike you know the problem is elsewhere, either weak spring or misalignment of hammer strike.

If the nipple taper is the problem you should be able to dress the nipple down a small bit at a time so you get first strike ignition without the nipple being so loose it won't stay put. Also, sometimes, a shorter or longer nipple will cure a problem like this.

[Marcruger]

My mental rule is that if it doesn't fire on the first snap, but does on the second, you were simply seating the cap with the first snap.  I'd turn down that nipple a bit with a drill and sandpaper.  God Bless,   Marc