Cimarron/Uberti Light Primer Strikes

[W.T.]

Before I go off to a gunsmith with checkbook in hand, thought it wise to check on other folks' experiences with light strikes.

My new 45lc Bisley frame Cim/Ubertis came with an extremely light yet clean trigger-pull and let-off.  On wringing them out for the first time, I got FTFs on all five economy-brand "service" rounds loaded.  After reloading with cowboy loads, two of five failed to fire  - working the trigger over and over again, they eventually came to fire more and more reliably and mostly ate both cowboy and service rounds fine.  At the end of the day, there were only two service rounds (out of two boxes) that wouldn't light up.

The pin is obviously hitting them a little light - working the trigger group in over a long range session apparently freed things up enough to get cleaner hits, but that spring's action is still too light for reliable performance, especially as I shop around at shows for cheapo 45lc fodder to burn while I learn this game and expect to be finding primers of varying hardness.

Don't want to mess up the light and crisp pull and let-off that I was fortunate enough to get "out of the box", so rather than just getting online and ordering any old replacement spring, thought I'd ask for suggestions.  Thanks for your thoughts and obeservations.

[Driftwood Johnson]

Howdy

A couple of things come to mind. I'm assuming these guns are brand new and have not been 'monkeyed' with by anyone?

A light trigger pull can be partially the result of a light hammer spring. The lighter the hammer spring is, the less force it applies vertically to the tip of the trigger that slides out of the full cock notch when you pull the trigger. If the full cock notch bears against the tip of the trigger (it's called the sear) with less force, then the trigger has less friction to overcome when tripping the hammer. I have often replaced a hammer spring with a lighter one in order to help achieve a lighter trigger pull. A light hammer spring, that may not be quite enough to light off primers, may be part of the reason you have a light trigger pull. Not the whole reason, but part. You may need to go the opposite direction, and add a little bit of force to your hammer spring. If you do this, you will probably increase your trigger pull slightly.

The reason many shooters can get away with light hammer pulls and light trigger pulls is they have reduced the friction in the system to an absolute minimum. So the hammer spring has less work to do to fire a primer, because not as much of its energy is wasted overcoming friction. You are apparantly seeing some of this right now. As you continue to work the action, you are probably polishing some rubbing parts and reducing the friction in the system.

If it wuz me, first thing I would do is take a look at the hammer spring, where it is screwed into the grip frame. Remove the grips, and see if the hammer spring is screwed down tight against the grip frame. It might for some reason be not screwed down all the way. There is an old gunsmith's trick of putting some sort of spacer between the hammer spring and the grip frame to lighten the effort of the spring. If the spring is not hard against the grip frame, make it so. Your problems will go away, but you will have slightly increased the effort to cock the hammer and probably slightly increased the trigger spring.

If the spring is screwed down all the way, I would look for signs of rubbing. Is the hammer moving freely when it falls? is it rubbing on one side of the frame, or the other side? If the hammer is rubbing on the frame, try loosening the hammer pivot spring, just a quarter turn or so. The frame may be pinching the hammer as it falls.

Take a look at how far the firing pin pokes through the frame when the hammer is all the way down. It is supposed to protrude .045-.056 when the hammer is all the way down. You can get a rough idea of how far the pin protrudes through the pin by laying a drill bit of known diameter next to it. If the pin does not protrude enough, you might be getting light hits. That is probably a job for a smith.

Next I would completely strip the gun, looking for signs of rubbing, rough surfaces, or burrs. You may or may not be comfortable doing this. If I found an offending rough surface, or burr, I would smooth it a bit. But be careful, some surfaces should not be touched, like the full cock notch/sear engagement, unless you know exactly what you are doing.

Hope this is of some help.

You may find you have to accept a slightly heavier trigger pull to get the reliability you need. It's hard to know from here just how light your trigger pull is. I have a digital fishing scale I use to measure mine. I like a trigger pull right around 2 1/2 pounds. Aything lighter than that and I am uncomfortable with the gun. I have one Colt that had a trigger pull only around 1 1/2 pounds. I put in a new trigger pull to boost it a bit to where I wanted it. However, this gun still had a pretty light hammer fall. Rather than monkey with the springs anymore, I only shoot loads in it with Federal primers, because those have the lightest, easiest to fire primers.

[W.T.]

Thanks, Driftwood.  These are indeed brand new, unfooled-with pistols.  In an earlier post about the light pull, several responders mentioned that Cimarron had apparently shipped at least a few with very light pulls, and that some folks had sent them back for re-working.

Just spent a good while cleaning them up after yesterday's session and saw no evidence of the hammer rubbing against the frame, the spring is well fastened to the grip frame, and pin protrusion is correct.  As noted in the first few spins around the cylinder, the primers were all well-dimpled by the pin, but apparently just not hard enough to set the primer off.  Weird that the strikes were just shy enough of full force to do the job, yet left a good impression.  That(mostly) resolved itself with use: perhaps there had been a little bit of binding at the base of the hammer where it can't be easily seen that eventually began to loosen up.

Looks like the only thing to do is to install a "standard" spring if the problem doesn't go away completely.

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