1851 Pietta timing help

Background:

Some years ago I got an 1851 Pietta and shot it now and then. The last time I shot it I had a terrible problem with it sucking caps and getting into the action, and to make things worse, I didn't clean the innards. More time passed, I got it out, cleaned everything out, the innards looked okay (though worn in some places), and it wouldn't go into half cock.

More time passed, and a couple of weeks ago I decided to see if I could fix it. I got one of the parts kits from Cabela's that contains a hammer, bolt, bolt spring, trigger, hand, and mainspring. I've just spent several frustrating hours with it. Disassemble, assemble, try it, iterate. Here's the best I've been able to do after trying various combinations of the old parts and new parts ...

The new trigger is simply too long and won't fit in the trigger guard!! I decided not to reshape it at this point. The new hand seems to be too long and with it the cylinder just doesn't lock up anywhere close to correctly. The new bolt fits okay, but the old one seems to fit the cylinder slots a bit better. So the parts I'm now using are:

New hammer
New bolt spring
New mainspring
Old hand
Old trigger
Old bolt

This has resulted in things ALMOST working:

BUT

What I've discovered is that if I SLOWLY bring it to full cock, I hear a click, and then when I release the hammer the cylinder is locked up correctly. But if I cock it by pulling it back all the way quickly, the cylinder is rotated too far and doesn't lock up. If I cock it by pulling back all the way SLOWLY, it clicks like it's full-cocking, and then if I release it the hammer moves forward just a hair and click fully into locking the cylinder in the proper position.

What are your thoughts on the best way to adjust this to get it right? Any insight will be appreciated. Just not sure what "minor" modifications to this setup I should try, or if I should put all the new parts into it and then mess with modifying those as necessary.

Yeah. That's what I was thinking -- but puzzled by the fact that this is the original hand that didn't used to be too long. Maybe it's "too long relative to the new hammer"? There's enough lever on lever action in these things that I wanted to be sure I wasn't missing something else.

I guess, then, that a few licks with a file and a little trial and error should yield the desired result.

I think I'm quite close and filing the hand should do it. I'll constrain my usual inclinations and approach it very carefully. It feels like the adjustment is only going to be in the thousandths of an inch. Then I can move on to some of the other common improvements -- primarily better nipples and addressing the issue of the caps coming off. It's a nice little gun and I plan to try to use it in local informal NMLRA matches on a monthly basis. Now that I have all this disassembly/assembly experience, I can clean it the way it should be, and that will avoid further problems.

Thanks for the detail. I've generally attempted to avoid revolvers in my life. All that angular motion, polar coordinates, etc. is a little intimidating.

The situation has improve noticeably simply with working the action (cocking repeatedly). So now failures are quite intermittent, and it otherwise locks up solidly. However, I can repeatedly induce a failure by pushing the hammer to the left with moderate pressure as I cock it. If the hammer is pulled straight back with no leftwise pressure, or is pulled back with pressure to the right, there are no failures to lock up.

I don't hear three distinct clicks. I hear the 1/2 cock click and the the simultaneous full cock and cylinder locking click. I can certainly SEE the bolt drop, but I don't hear a click. As the bolt drops out of sight into the frame under the cylinder, I hear the 1/2 cock click, and that's it.

Ah, yes ... I recall seeing something about that now. Thanks for pointer. The bolt arm is clearly worn, but I'll try spreading the left bolt arm out and see what the result is. I may end up substituting the new one for it and seeing what happens , although as you point out, that will require some fitting. At least this is progressing in the right direction and converging on a good (and safe) solution. There's something a little scary about your chamber randomly not aligning with your forcing cone when the hammer falls.

Interesting observation. It was my original intention to use all the new parts, but the trigger was too long to fit in the trigger guard and so I thought I'd just save some time and use the old one. But that's one example of a dimensional difference, and there are others.

The new hammer is case hardened, and the old one is not (it's just unblued steel). The new one is also obviously a tiny bit thicker. Both springs are slightly different from the old ones, the bolt seems to be slightly thicker (I haven't mic'd it yet) with a slightly different contour, and the new hand also has a slightly different contour as does its spring.

When I decided to punt on the new trigger, and then used the rest of the new parts with the old trigger, it just didn't work and I started to mix & match. It's worth grinding down the trigger and trying all new parts since I'll probably end up using the new bolt anyway and will need to work on fitting it.

Thanks, I'll take that into account. These triggers don't appear to be case hardened. The old one is standard gray/silver steel without any evidence of heat treating, though I suppose it may have been heat treated. The new one has some sort of black oxide (I presume) finish on it. It's not only too long for the trigger guard, but it's quite inelegant-looking compared to the original -- an obvious product of CNC machining. The front face of the trigger notch (for lack of a better term) also shows some unevenness and tooling marks

This is definitely a pre-2015 model -- in fact, quite a bit pre-2015 as I recall. It has the rounded (not squared off) trigger guard. The trigger shows no color case hardening, being just uniform light gray/silver in color, but I suppose may be case hardened nonetheless? Likewise the hammer is not color case hardened, but the frame, loading lever, and ram are. So it looks like the bottom gun here. The replacement trigger looks more like the one in the top picture -- which makes sense because that trigger guard is larger and will accommodate the longer trigger. That squared off trigger guard looks odd to me. I prefer the rounded one.

So at this point ... TOTAL SUCCESS. I spent what seemed like several hours with my Dremel shortening and contouring the new trigger. A careful side x side comparison of the old and new triggers shows a distinct difference in dimensions both in the trigger lever length and at the bearing surface. See the picture below. The old trigger is on the left and the new one on the right (prior to shortening it).

Once reassembled, the gun functioned flawlessly and I couldn't get it to fail in locking up or half-cocking. The only issue is that I ended up using the old bolt. This fits the cylinder perfectly, and using the new one would have meant more time in filing/stoning and fitting. I need to get on with my life if I can. The old bolt is not at all in compromised condition and seems to have only some scratches along one leg (probably from cap fragments). In addition, to the bolt itself needing fitting, the new one is also slightly different dimensionally i n terms of the length of the legs. This MAY not make a difference, but I don't want to face that prospect when I now have a gun that seems better than when it was new. Very tight, very crisp.

Thanks much to all of you. I really appreciate it.

Well, I just got 3 lbs that will be good for the pistol. However, I do plan on making some additional mods -- like to the grip and sight. And I need to make a reloading stand for it. But I'm on my way with it. Just ordered some Teso nipples for it and some more RB.