An almost new Uberti 1866 in 44-40 with Light Hammer Strikes Finally FIXED

[Frontier Lone Rider]

I got another new Main/Hammer Spring and re-shaped the claw end curvature.  I increased the end curve to lift the Hammer more aggressively when falling.  The Hammer now snaps when one pulls the trigger to fire the rifle.

 

An almost new Uberti 1866 in 44-40 with Light Hammer Strikes

 

I bought a NIB A. Uberti/Cimarron Short Rifle “Yellowboy” 1866 in 44-40 with a 20-inch full octagon barrel in SEP 2021.

I installed a Stainless Steel Mag Tube Spring, SS Follower, and a Brass Mag Tube Plug.   Later I installed a Pioneer Works Third Generation Super Short Stroke Kit and Light Action Springs 12 DEC 2024.

 

I cleaned the rifle with Ballistol and put it away.  This week I pulled it out of the safe and shot one round.  It appears to be having light hammer strikes.  I replaced the; Firing Pin, Firing Pin Spring, Firing Pin Extension, Firing Pin Extension Stop Wedge, Uberti Hammer, Blued Hammer Screw, Hardened Lever –Spring Screw, and Uberti Mainspring, and the Main Spring Screw. I purchased the Hardened Screws from VTI and replaced the Uberti Hardened Trigger Spring Screw, Chrome Plated Loading Gate, and Blue Side Plate Screws,     May 2026.  It is still experiencing Light Hammer Strikes.  What do I need to do next?

 

Frontier Lone Rider

[Colorado Coffinmaker]

 

Lone Rider:

 

After reviewing your laundry list of replaceable, there is an appropriate receptacle for the Rifle.  Appears you have replaced everything that moves.  Also, appears you have replaced the "light action springs" with an OEM Uberti Main Spring??  With lighter action springs, you Las need the firing pin return spring to be lighter than stock.

 

If you have returned to an OEM Uberti Main Spring and are still experiencing light hammer strikes, you may well have a serious Head Space issue.  Optimum head space is .004.  Anything over .008 is flirting with light primer strikes.  You didn't mention whether you had replaced the Firing Pin with an Extended Firing Pin.  Pioneer sells an extended Firing Pin,

 

The Head Space problem can relate to the Short Stroke links.  Without serious machine work, a head space issue can be resolved with extended length links.  Pioneer can provide those.  Check the head space between the cartridge head and the bolt face with tapered automotive feeler gauges.  Most likely, you would need a set of links about .005 or .006 over nominal length.

[WymoreWrangler SASS 46187L]

Change primers...

 

[Griff]

You put the rifle away in the safe a year and a half ago, took it out, fired one round and determined it suffers from light primer strikes?  How many strikes did it take for that one round to fire?  Did you clean the rifle before firing it?  When I work on my own guns (the only ones I'll work on), I test after changing each thing.  I've only changed one Uberti mainspring in a rifle, and that was after it broke, maybe 5-6 years ago.  In a 1986 production 1873.  And I put a stock replacement back in.  My suppository cowboy revolvers get lightened mainsprings;  rifles & C&B revolvers, nope.  

[Garrison Joe, SASS #60708]

First = Clean it all with a standard bore cleaner,  including the firing pin, the bore it rides in, and the firing pin extension.  Then clean the trigger/sear area.   Kinda sounds like you could have congealed Ballistol in the action parts.

 

If after that cleanup, you still have problems, then check headspace.  And check with a Winchester factory 44-40 round.  

 

"Firing the Parts Cannon" at a toggle link is rarely necessary - especially with an almost NIB gun.  If you cannot find the problem, then let a gunsmith who can find the problem take a look and fix the (probably) one thing needing fixing.

 

good luck, GJ

[Frontier Lone Rider]

2 hours ago, Griff said:

You put the rifle away in the safe a year and a half ago, took it out, fired one round and determined it suffers from light primer strikes?  How many strikes did it take for that one round to fire?  Did you clean the rifle before firing it?  When I work on my own guns (the only ones I'll work on), I test after changing each thing.  I've only changed one Uberti mainspring in a rifle, and that was after it broke, maybe 5-6 years ago.  In a 1986 production 1873.  And I put a stock replacement back in.  My suppository cowboy revolvers get lightened mainsprings;  rifles & C&B revolvers, nope.  

The Light Hammer Strikes are observed when pulling the trigger.  The Hammer does not move the firing Pin Extension when struck.  

This issue has nothing to do with primers.

 

I had cleaned the rifle thoroughly prior to replacing the parts, including the space where the Hammer moves against the Main Spring.

[Colorado Coffinmaker]

 

Other than Head Space, the firing Extension Rod is either dragging in its bore thru the frame, or most likely, dragging in the bore of the Breach Block (bolt).  Be sure to check the head space as well.  I hope you didn't install the extension rod stop wedge backwards.  You may also wish to polish the contact side of the wedge and insure there are no burrs in it's channel to restrict its movement. 

[Abilene, SASS # 27489]

9 hours ago, Frontier Lone Rider said:

The Light Hammer Strikes are observed when pulling the trigger.  The Hammer does not move the firing Pin Extension when struck. ...

With the hammer cocked, push on the end of the firing pin extension with your thumb.  Does it move forward smoothly and spring back when released? 

 

One nice thing about working on light primer strikes is that you can test by using empty primed brass - no need to live fire at a range.

[Colorado Coffinmaker]

 

Frequently, a Toggle Link will seem to bind when the action is closed without a cartridge, and function just fine when a cartridge corrects the alignment.  Full Firing Pin and extension rod travel should be tested with an unprimed case for full travel. 

[Frontier Lone Rider]

10 hours ago, Abilene, SASS # 27489 said:

With the hammer cocked, push on the end of the firing pin extension with your thumb.  Does it move forward smoothly and spring back when released? 

 

One nice thing about working on light primer strikes is that you can test by using empty primed brass - no need to live fire at a range.

Yes, everything seems to move smoothly.  Especially when working the action.

 

I am going to tear it completely down again and check for rough spots or burrs.  Just clutching for straws here.

 

I have three other identical rifles except two are 24-inch and the other is 20-inch.  I had installed the Pioneer Super Short stroke Kits in each rifle, and they seem to work without a flaw.  It just bugs me that his latest one is not working as I had hoped.

[Griff]

FWIW, I installed the PGW kits in 2 1873s w/o an issue, but when I installed the 3rd kit in my steel framed Henry (also Uberti), I had a fitment issue.  I.e. lever didn't come back to the lower tang, let along disengage a trigger block safety had one been there.  A call to PGW yielded the reminder to read the instructions, and had me fitting the carrier arm properly.  BTW, how I check headspace is to load a cartridge with a piece of "Plasti-gage" on the back and close the action.  size ranges are:

Green (SPG-1): 0.001--0.003 in. (0.025--0.076 mm)

Red (SPR-1): 0.002--0.006 in. (0.051--0.152 mm)

Blue (SPB-1): 0.004--0.009 in. (0.102--0.229 mm)

Probably not the "gunsmith approved" method, but I had it around when I wanted to check a rifle... and if it's good enough for my 427... it's gooder'n enough for a Uberti!

[The Original Lumpy Gritz]

Put the old hammer spring in and try it.

Clean with a modern solution like Breakfree CLP. 

[Dusty Devil Dale]

Remove the firing pin and make sure it isn't bent.  Then take a drill bit of appropriate size and CAREFULLY, with fingers only, spin it in the Firing pin recess very lightly to remove any encrusted lubricant and cellulose.  Encrusted material will prevent the FP from advancing far enough forward.  

[Frontier Lone Rider]

There are no burrs or any dragging of any of the parts.  The action all works very smoothly.  The issue is; the hammer does not strike the Firing Pin Extension with any force.  I have installed a new Main Spring, but the Hammer barely strikes the Extension, definitely not with any force.  The Hammer moves freely when moved with my thumb.

[Abilene, SASS # 27489]

When you cock the hammer with your thumb, how does the tension feel compared to your other rifles?

[Timothy]

My 66 gave light strikes suddenly after years of perfect function. I tightened the screw under the lever that contacts the mainspring and back to 100 percent. I did loose its previous excellent trigger pull but its an old gun i rarely shoot maybe someday i'll send it to a professional.

[Lucky R. K.]

On 6/20/2026 at 10:33 AM, Frontier Lone Rider said:

An almost new Uberti 1866 in 44-40 with Light Hammer Strikes

 

I bought a NIB A. Uberti/Cimarron Short Rifle “Yellowboy” 1866 in 44-40 with a 20-inch full octagon barrel in SEP 2021.

I installed a Stainless Steel Mag Tube Spring, SS Follower, and a Brass Mag Tube Plug.   Later I installed a Pioneer Works Third Generation Super Short Stroke Kit and Light Action Springs 12 DEC 2024.

 I cleaned the rifle with Ballistol and put it away. 

Your post does not say that you test fired the rifle after installing all those parts. If that is the case, I suggest that you loosened the tension on the mainspring and failed to re-tighten when finished, thus giving the light strikes. I actually did the same thing once when working on my rifle. At my next match I was having light hammer strikes for a while before I remembered the work and tightened the tension on the spring.

Lucky 😁

[Frontier Lone Rider]

1 hour ago, Lucky R. K. said:

Your post does not say that you test fired the rifle after installing all those parts. If that is the case, I suggest that you loosened the tension on the mainspring and failed to re-tighten when finished, thus giving the light strikes. I actually did the same thing once when working on my rifle. At my next match I was having light hammer strikes for a while before I remembered the work and tightened the tension on the spring.

Lucky 😁

I have tightened the screw as tight as it will go.  Yes, when it is loosened, the strikes get even weaker.

[Sedalia Dave]

@Frontier Lone Rider what was the fix???

[The Original Lumpy Gritz]

21 minutes ago, Sedalia Dave said:

@Frontier Lone Rider what was the fix???

We gots ta'know! 🤠👍

[Colorado Coffinmaker]

 

Ya!!  What was the FIX??

 

DITTO Lump Lump!!

[Frontier Lone Rider]

20 hours ago, Sedalia Dave said:

@Frontier Lone Rider what was the fix???

I had modified the original listing to include the fix.

 

Posted Saturday at 10:33 AM (edited)

I got another new Main/Hammer Spring and re-shaped the claw end curvature.  I increased the end curve to lift the Hammer more aggressively when falling.  The Hammer now snaps when one pulls the trigger to fire the rifle.

[Colorado Coffinmaker]

 

Ah So!!

 

Duh!!  I could have re-read the whole initial post 🧐 🙃

[Cemetery]

On 6/20/2026 at 10:33 AM, Frontier Lone Rider said:

I got another new Main/Hammer Spring and re-shaped the claw end curvature.  I increased the end curve to lift the Hammer more aggressively when falling.  The Hammer now snaps when one pulls the trigger to fire the rifle.

 

My '66 was been giving my similar issues like this randomly, will look at my main spring.

[Trailrider #896]

If not properly heat treated they may, over time lose their temper. It doesn't happen in most cases, but it does happen.

[Garrison Joe, SASS #60708]

Flat springs fail to hold their original tension very often.   (It's one reason that Uberti puts a heavier spring in guns than is needed.)  It's also a reason that modern designs predominantly use coil springs rather than flat springs.

 

If you have problems related to a soft hammer fall, one of the very first things to look at is that the spring in the gun has lost tension.  And if you are not the original owner of the gun, so that you know the history of parts replacement on the gun, it pays to suspect the most common cause of the problem.

 

A lot of parts were thrown at this gun (called "firing the parts cannon") that  were unnecessary.  They may have improved some part of the operation of the gun, but none of them solved the initial problem until the hammer fall speed was carefully investigated and a new hammer spring fitted.  

 

good luck, GJ

[Frontier Lone Rider]

52 minutes ago, Garrison Joe, SASS #60708 said:

  They may have improved some part of the operation of the gun, but none of them solved the initial problem until the hammer fall speed was carefully investigated and a new hammer spring fitted.  

 

good luck, GJ

I had initially replaced the Main/Hammer Spring, but it did not resolve the issue.  So, I purchased another Main/Hammer Spring to re-shape.  If it had not worked, I still had the 1st new spring to put back into the rifle.

[Garrison Joe, SASS #60708]

Any part installation has to be checked to verify that it has resolved the problem.  Not all new parts will fit properly.  I take it you have found this out the hard way.

 

good luck, GJ

[Dusty Devil Dale]

Hopefully, you do realize that there are TWO screws that contribute to leaf hammer spring tension.   I've seen instructions that say to completely tighten either one or the other.   I use them in combination, but they do need to be readjusted periodically.  

The springs will not lose as much power in storage, if you can remember to loosen them for long storage, and retighten them for shooting.  For reference, I back my front spring screw off one full turn.  It works for me.