In the past two months, I have had two Uberti revolvers (an 1860 and 1851 Navy) both develop miss-fire issues due to weak mainsprings. A weak mainspring may make for a light, smooth action, but it does nothing for reliability when the cap needs a good WHACK! There are reduced power spring kits all over the place for the CAS crowd. Does anyone make a full-power or heavy duty mainspring? If worse comes to worse, I will buy Colt factory SAA mainsprings and call it a day.
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November 1, 2010, 12:18 PM
Are you sure that the nipples aren't too short? I've had that problem on two of my 1860 Colt types.
November 1, 2010, 02:04 PM
Missfires with both factory and Treso nipples...but not all of the time. if it was all of the time, it would be much easire to diagnose.
November 2, 2010, 01:45 AM
One thing you can do to increase the psi on the striking surface of the nipple is to slightly bevel the top opening of the nipple. I.E. you end up with about 50% less surface area on the top of the nipple and the psi delivered to the surface of the nipple is doubled. That is one way you can still have a light hammer fall and still pop the caps. The positive effect is greater if the nipples have flat faces on the top like the old Uncle Mikes/Butler Creek or TOW SS replacement nipples. I used an 1/8" drill bit and it made a difference. On another gun I chucked the nipples in a drill and stoned or filed the outer edge down.
Be sure the hammer face just barely touches or is only a thou or two from the top of the nipple when all the way down. Sometimes you need to shim a nipple or two out a bit to be sure it is getting struck fully.
November 2, 2010, 11:33 AM
Would you happen to have a picture of this procedure? I am having a difficult time visualizing it...
November 2, 2010, 11:55 AM
Photography is my weak point. No can do. Maybe a rewording is in order.
Basically I BARELY drill the hole in the top of the nipple a little bigger. This bevels the inside edge of the hole which reduces the surface area causing the blow of the hammer to strike a smaller surface area and therefore you get more PSI onto the contact area. Also more of the cap power is directed down the flash hole.
On hard nipples that dull the drill, I bevel the outer rim of the nipple a bit to reduce surface area.
The first thing I'd do is be sure the hammer face just touches the nipple before modifying anything. I hold the gun and push with my thumb on the cylinder face and with my other thumb I push on the hammer (in the down position) and see if the hammer and cylinder move in tandem a smidge. If so, the hammer is contacting the nipple and I can ever so slightly push the cylinder back and forth. If the light strikes don't reliably detonate the cap then I modify the top of the nipples.
November 2, 2010, 01:37 PM
Look at the photos in Posts #6 & #12 of the following thread for a simple common fix that doesn't require permanent modification and is reversible.