Chaparral 1876 45-75 Mis-Fire question

[OKDEE]

I have the above rifle.  I have been twiking it and learning about gunsmithing!  Just a side note, my grandfather was a practising gunsmith in Kansas City back in the 20 an 30's!  So I may be following in his footsteps. 

I have sent it back to be worked on by Charter Arms and an at that point where I have just (Currently) one problem.  They resolved one of my problems and attempted to correct this one, but did not.  I prefer at this point in time, to work on it myself or have my (Real) gunsmith work with me.

Misfires!   Sometimes it misfires 4-6 in row, sometimes it fires 4-6 in a row with no problems.    The misfires occur with both types of brass, 348Win and Jamison 45-75.

I use mainly 348 reformed brass.  headspace for these run about .003

I also use some Jamison 45-75 brass and the headspace is about .005 +

I would like to add about .002 to the tip of my firing pin, to see if that would help.  I have a great gunsmith here in Houston, Texas that can do the job.  I do not want to puncture the primer, merely extend the firing pin and properly harden it.  To see if this would get rid of the misfires.

Has anyone done this?

Has anyone else looked at the hardness factor of the firing pins?  I know that on my Uberti's, both rifles and pistols, the firing pins were always way too soft.  Over time of shooting, there is a mushrrom effect that occurs on the front of the firing pin that strikes the primer and in due course shortens the firing pin to the point of misfires.  My gunsmith would properly harden the firing pins on the pistols and  I would purchace new machined steel firing pins for the rifles.

I also wonder if it is possilbe that my chamber is not cut correctly for the brass I am using.

Your thoughts and experiences are appreciated for this Journey of mine!   

Sincerely
Oklahoma Dee

Now in Houston, TX

[Harve Curry]

That's a tuff question without being able to handle the firearm or see the cartridges.
Somethings you didn't mention are:
What the mis-fired primers look like.
Hammer spring heavy enough.
Hammer dragging on something, slowing it down.
I have seen very light triggers cause interference, when pressed light enough to trip the sear, but not enough to get out of the way of the hammer's surface. Hence light primer indent.

[Grizzly Adams]

Morning, Okdee,

Just some ideas to explore.

What kind of primer are you using?  Are the strikes consistently light, or does it vary?  In other words when it fires 4-6 times in a row, are those hits deeper that when it misfires? 

The fact that iit does fire sometimes (4-6 times) makes me wonder if it is the length of the firing pin or some kind of obstruction. Have you had the firing pin out of the bolt yet just to make sure it is straight and that there are no burrs on the pin or inside the channel?   How much protrustion does the pin have?   One alternative to adding lengthto the tip might  be to reduce the shoulder just aft of the tip.  Follow me?

Keep us posted!

[Hoof Hearted]

Dee

You asked for help with this problem on the "production problems" thread earlier

You need to check your headspace as I explained to you there with and without a fired case and eliminate the extractor issue if it does exist (I also provided that I would walk you through how to check for the myriad of things that could be complicating your misffire issue if you contacted me via the phone). All of this is FREE

Yer pard,
HH

[john boy]

Dee, I wouldn't touch a thing until you tried putting a piece of leather under the main spring - near the screw.  Will put additional foot pounds on the hammer to impact the firing pin more

[OKDEE]

Thanks you all!  Here is some more information and results!

Headspace is okay.  For the 348 Winchester reformed brass, it is about .003 and the Jamison 45-75 brass it is about .005-.007

I am using Winchester Large Rifle and Remington 9.5 Large Rifle primers.  I have had a prior hammer problem, in which I had to stone the side of the receiver and the location of the hammer spring was adjusted.  I think it was a bit too light.  and there was some dragging going on.

After I had loaded my rounds,  I rechecked the depth of the primers and noticed a few were not seated flush with the bottom of the brass.  I ran the rounds back through the primer stage and seated them again, just to make sure.

I then headed to the range and something strange happened!  Out of 20 rounds fired, I only had two misfires!  Gosh  It was like Christmas all over again!

I noted the two misfires as very light hits on the primer.  The others were a good hit.  I am going to pull the firing pin out and see if there is some kind of obstruction and maybe grab Grizz's idea about sloping some shoulder off!  Also I will revisit the hammer area and look closer to any possible area's where the hammer may be slightly grazing something.

As a side note, I have a Marbles Peep Tang sight and now a Cabelas's Globe front site and I am really getting some nice groups now out 100 yards.

Thank you all for your input.  This is a good trip. FINALLY!

Continuing the journey!

Oklahoma Dee

[Hoof Hearted]

Dee

It appears that you have fixed all of your problems!
Sorry that you are now selling the rifle (here's a shameless plug for your ad over on the SASS wire)

[OKDEE]

Dee

It appears that you have fixed all of your problems!
Sorry that you are now selling the rifle (here's a shameless plug for your ad over on the SASS wire)

Not so, HH!    I am selling the carbine that has no problems.  I am keeping the one that I had all the trouble with, shes's a keeper!

[Grizzly Adams]

Not so, HH!    I am selling the carbine that has no problems.  I am keeping the one that I had all the trouble with, shes's a keeper!

Hmmmmm....Sells the one that works and keeps the PITA!   I tell ya fellas, I don't know about our boy, OkDee!