Question about nipple and bolster thread weakness

[Mcat]

I’ve just been working on an original Daniel Risher half stock back action percussion rifle from the 1840s. I have put in a new tumbler with fly. The old one would not hold on half cock. Now it does. Since the wood stock has shrunk a bit you have to set the trigger before cocking to get the sear out of the way of the set trigger released. When I first got the rifle about a year ago I removed the nipple and bolster and found them jammed with crud which I was able to clean out. The bore looked pretty good. 36 caliber. After making the tumbler repair, I wanted another look at the barrel so removed the bolster and nipple and shone a bore light up the barrel from the bottom. All pretty good. However after replacing the bolster with a bit of anti seize I found when screwing in the nipple that it was a bit loose going in and in fact would not seat, just spin at the bottom. I found a new nipple of similar size which seemed to thread in, but it too spins (more tightly) at the bottom. I assume the problem is with deteriorated threads in the bolster. I am also guessing that it would be dangerous to shoot in this condition. I don’t think I have the skills to repair the bolster. Any thoughts? Thanks.

 

[2 shots]

yeah.. dont shoot it in that condition. measure the nipple and see if there is enough room to rethread bolster to the next size up. nice lookin rifle.

 

[64Springer]

Your nipple threads have to be WAY undersized to have the nipple spin when screwed all the way in.

That, or the threads in the bolster are non-existent.

Before trying to drill and tap the existing bolster threads, determine the exact thread that's currently there and find a nipple to match those threads.

 

[Dusty_Traveler]

What that guy said. Oversize nipples are a thing. I am working on an O/U combination gun, the rifle barrel has a .250-28 nipple, and the shotgun barrel a .285-28. Use a set of calipers and measure the exact diameter of the female nipple threads in the drum. A thread pitch gauge is needed to find an exact match of the pitch, if they aren't already too boogered up from spinning nipples.

 

[Mcat]

I’m thinking they are too corroded. I just screwed in another nipple and it went in quite tight but likely making its own threads. Not safe.

 

[64Springer]

Those threads are roasted.

Drill and tap to the next size up.

Maintaining the original angle so the new nipple lines up with the hammer.

 

[Sam squanch]

You may be better off with a new drum.

 

[64Springer]

That drum has plenty of meat left in it.

 

[Dusty_Traveler]

I would not drill and tap the next size up. There's just not enough meat there for me consider it safe.

I would remove that drum, get the dimensions of it and get one from track of the wolf. One that has not been drilled. They also sell a drum drilling jig. I have one of these and it works great. Just double check all your alignment, no, triple check it before drilling. and take care to keep the tap straight.

 

[Dusty_Traveler]

Upon further examination, if there are threads there but they're just full of anti-seize, I would clean them out fully and still try to get a diameter/pitch measurement. It's hard to tell just by the photo.

I would do this before replacing the drum. You still might get away with it being an oversized nipple.

 

[Mcat]

Thanks everyone. Advice is greatly appreciated. I’ll have another good look at the bolster threads tomorrow and move on from there. FYI here is another auction of a Daniel Risher half stock with some bio info I found after making my purchase.

 

[Dusty_Traveler]

That’s a beautiful rifle.

 

[Mcat]

Yeah. I have a fondness for backaction percussions. But there is sure nothing to complain about such a rifle as the front action above.

 

[Dusty_Traveler]

Where'd you get the tumbler/fly? What did that repair entail? Did everything clock correctly?

 

[Flint62Smoothie]

I myself see plenty of meat there to go an over-sized nipple, of which Whitaker Machine Shop sells some.

 

[Mcat]

Where'd you get the tumbler/fly? What did that repair entail? Did everything clock correctly?

Trackofthewolf. Had to file down the post through the bridle to fit. Put the tumbler square in my drill press and held a small diamond file against it to keep it round. Slight difference in the length of the stirrup, but got it to fit by strong compression of the main spring when reinstalling. The fly fit under the bridle and seems to be working fine. The tumbler square was in alignment with the original. So all was well.

 

[Dusty_Traveler]

Trackofthewolf. Had to file down the post through the bridle to fit. Put the tumbler square in my drill press and held a small diamond file against it to keep it round. Slight difference in the length of the stirrup, but got it to fit by strong compression of the main spring when reinstalling. The fly fit under the bridle and seems to be working fine. The tumbler square was in alignment with the original. So all was well.

Awesome! Well done.

 

[The Crisco Kid]

A good machinist can make a duplicate drum that can be aged to match the original. I'd be a little suspicious of the threads on the drum if the nipple threads are that bad. At least remove the drum and check the condition. I think I would just replace it with one you know would be safe. It's a simple repair and the drums you buy won't look like the original.

 

[appalichian hunter]

I am with The Crisco Kid on this one, it's always nice to be able to repair an original part but I believe safer just to re-place the part. Would be embarrassing to need to go to the emergency room and have a vent fished out of yer skull. Or a drum out the guy's head next to you.

 

[SDSmlf]

I have been present during a few spontaneous disassembles. A couple of nipples and one drum, luckily no injuries. After investigation, loose or suspect threads were the common denominator. Usually with a statement like ‘I thought I could get by’ or ‘thought I could make it work’. Our ‘toys’ have a rather energetic energy source and can be dangerous if threads or other mechanical components are compromised.