stripped niple threads in cylinder

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zcar75

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What size tap should I use to re-thread the cylinders in my Pietta 44 1858. Thanks.
 
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tap

Don't know off hand. What I would do is go to Track of the Wolf and check on what sizes are available; they frequently have oversized threads for particular nipples. That might make things easier for you.
Pete
 
Piettas use a metric thread, M6X0.75, for the nipple threads. Should be able to get a tap for that at most any decent hardware.

A Helicoil is not advised. They do not leave a flat surface at the top for the nipple flange to seal against. I believe they'll handle the pressure structurally but that poor seal at the top may result in significant blow-by.
 
Mykeal, what if you placed a hard fiber spacer under the nipple and trimmed it down accordingly so it didn't bind on the frame?
 
zcar75 -I'm not really being a traitor to this site so everyone please forgive me . . . :D go over to CasCity and get on the SCORRS site - this is a site that is strictly for Remington shooters and there are a lot of fellows who do their own work on their Remmies - customize, etc. I'm sure that this problem has popped up for some of them and they can probably give you some suggestions . . . . . possibly a very easy fix . . . . . as has been suggested here - check out Track and see about the oversize thread as that is usually what it necessary to go to regardless if it is a BP revolver or a percussion longarm (short of changing the drum on a long arm if it has a drum instead of a patented breech). Good luck . . . you'll get it taken care of . . . .
 
I think...

I think I'd go for the tap instead of the helicoils. You might even be able to chase the threads and use new nipples made for that pistol, rather than going to an oversize nipple. (I guess I'd be careful with this.)

I take the nipples out of my pistols quite often. Not sure why I do that but I do. The result is that they always come out rather easily. I don't ruin many nipple wrenches trying to get stuck nipples out. They still fit nice and tight when I put them back in. When I put the nipples in I don't tighten them with a lot of torque.

Perhaps I am a little extreme on this point but I am the guy who takes the pistols completely apart to clean them (including the nipples) and I do that every time I shoot them. I am also the guy who is horrified at the thought of not being able to get the breech plug out of a front stuffer. I know there are plenty of folks on the forum who don't agree with me but I have never read a definitive reason to think I am wrong.

I guess it just seems to me that if you have two pieces of metal screwed together you have to be able to get them apart.
 
I'd be getting a new cylinder. Would be a PITA to have to worry about which nipple goes in which hole after cleaning. Keep the old one as a backup.
 
Just FYI, I spoke to the folks at Treso a number of months ago about their nipple dimensions. As I was having a problem trying to replace new factory Uberti nipples with their Treso nipples on an 1858. I couldn't get the damn things to start threading. Per our conversation they indicated that Treso nipples are manufactured at the VERY highest diameter spec. They said the reason was because their nipples are typically purchased as replacements to old worn out factory nipples. They also indicated that Pietta and Uberti can sometimes be all over the place with regard to their tolerances. I just happened to have purchased an Uberti that was on the ultra low end of the allowable diameter and was trying to put in Treso nipples that fell on the ultra high end. My point here is that unless you've really destroyed your threads you may be able to retap at the high end specs and use Treso nipples. It could be that your original thread diameter was on the very low end like my 1858 and you just wore out the threads of the original nipples. Good luck and let us know the details.
 
You can certainly rebuild the mating surface to better seal the helicoil, but you're getting into a difficult area. To do it right so that it would withstand the combustion chamber pressure seems to me would cost more than a new cylinder by quite a bit. However, I've never tried it, so someone with the skills, tools and experience may be able to do a fine job for little cost.

This problem has certainly come up a number of times, and people have claimed to have successfully repaired the threads with thread inserts (like Helicoils), simply restored them with a tap or rebored and tapped them for oversize nipples. There are also examples of such repairs that didn't work out. It all depends on how much damage there is and the three wise men: tools, skills and experience.
 
A heli-coil kit for these small metric sizes run well over $50 at jobber price, it includes a drill, tap, insert tool and several inserts. It's a propitiatory tap. A heli-coil thread insert is used extensively in the performance industry as both a repair for steel threads and initial replacement of aluminum threads.

As ClemBert posted there are 'major' and minor' tolerances regarding threads and the Italians tend to be all over the place size wise.

A NEW CYLINDER from cabela's is $39.95 and comes with six nipples.
 
Yup!

I agree it would be problematic to do just one chamber. If you can't chase the threads and make a new nipple of the same size work, then go oversize on all of the chambers. No way should you have just one offsize nipple.

I do agree with those who are saying a new cylinder is a good way to go.

Tnx,
 
Even if you run a tap into the hole you will not have the full strength of the original threads. The tap only removes metal in the way of screwing your nipple in.

If the damage is limited to only the first thread you are probably OK. Much further and I'd be looking into a new cylinder. $39.95 is a very cheap fix compared to a gunsmith, machinist, helicoil, doctor visit or worse.
 
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