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Measuring the Thread Form and Diameter of Antique Nipple Seats

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Just got a nice, old German half stock with a .52 caliber barrel. No nipple. Tried .250 and .255 diameter nipples but could not pick up the thread pitch. Without damaging the old nipple seat, how can you best determine what the thread pitch and diameter of the original nipple is?
 
Its likely a metric thread. Get a tap set and see which one threads in correctly. Dont force them or you may ruin the threads.
 
We tend to think of metric threads as being the "other" thread form and that they are standardized around the globe (they aren't). The metric threads were developing and changing through the percussion era. Whitworth was introducing his thread system and a lot of the US threads used then are long since obsolete. It is possible you may never find a nipple to fit and the options are to have a nipple made or to adapt the gun to take one that is readily available today. I would opt for the last choice. Follow Phil Coffins advise and do not attempt to identify threads using a tap unless you have years of experience cutting threads.
 
We tend to think of metric threads as being the "other" thread form and that they are standardized around the globe (they aren't). The metric threads were developing and changing through the percussion era. Whitworth was introducing his thread system and a lot of the US threads used then are long since obsolete. It is possible you may never find a nipple to fit and the options are to have a nipple made or to adapt the gun to take one that is readily available today. I would opt for the last choice. Follow Phil Coffins advise and do not attempt to identify threads using a tap unless you have years of experience cutting threads.
Good answer but how does one "Adapt" the gun to an available nipple?
 
Drill and tap to the next largest size of available nipple. Drill and install a Heli-Coil that has the desired thread. Drill, tap and install a bolt to plug the hole. Pin it so it won't unscrew then drill & tap that. As an absolute last resort weld it closed then drill & tap.
 
If you re-tap be sure you use the same thread pitch. IF you do not you will have only messed up partial threads. The only way around this is to drill to a larger size and re thread, removing the old threads. This is probably not possible.

The wood plug is a good idea to get an impression. Make it tapered. Cut it off a bit at a time and run it in several times to get a good impression to measure.

To properly drill and tap for a nipple you should not eyeball it. Use a drill press or a milling machine to drill straight and to correct size. After drilling do not break the set up. Tap in the same set up using a spud to guide the tap in straight. Drilling and tapping short blind holes requires better technique than other tapping jobs. You need as close to 100% good threads as possible for safety's sake.

I would not use a helicoil. Catching nipple in the face is a very bad day.

Welding up the hole will probably make a big mess. I might bush it with a machined liner and silver solder it in place. I would thread the OD of the bushing and partial thread the ID for the nipple. Then finish the ID threads after silver soldering so they are fresh and clean. Silver solder is the high temp stuff jewelers use, not the silver bearing tin solder plumber use.

Jobs like this are all individual and there is no univeral answer. Hopefully it is a 6mm x .75 or someting else that is common.
 
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If it is German it's more than likely it is 6mm which is the same as 0BA(British Association). .236" O/D X 1mm-.0394",471/2 degrees inc angle. BA was a development of Metric threads according to my early Machinery's Handbook..1914 Edition. Don't re-tap it. Find a good local Model Engineer and Cross his palm with an amount of Silver.. Nipples are not difficult to turn & screw cut. Getting the Hole right is the most important bit.. Small hole at the top for shot guns, Small hole at the bottom for Pistols and Rifles.. Full Dimensions by PM if required.. OLD DOG..
 
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Just got a nice, old German half stock with a .52 caliber barrel. No nipple. Tried .250 and .255 diameter nipples but could not pick up the thread pitch. Without damaging the old nipple seat, how can you best determine what the thread pitch and diameter of the original nipple is?
You might want to try metric thread, however the threads were most likely hand cut. If you are real serious about shooting the gun you will most likely have to drill it out and retread and install a threaded bushing to accommodate the new nipple. I have been there and done that. Worked out fine the nipple comes out and the bushing stays in place. Good luck.
 
Thanks a million for all your "fixing" techniques and ideas. One or another will put this fine, little piece back on the firing line.

This is what makes our forum so invaluable.
 
Flintlock LLC out of Indiana, they come to Friendship. They have lots of different odd nipple sizes. I have taken a gun to him, he rummages around to find a nipple that fits it. I have a english sporting rifle and it is an odd sized nipple. I was going to see what he had at Friendship in June, but it was canceled.

The other option is to send him the barrel and have him fit one for you and send it back.

Fleener
 
Flintlock LLC out of Indiana, they come to Friendship. They have lots of different odd nipple sizes. I have taken a gun to him, he rummages around to find a nipple that fits it. I have a english sporting rifle and it is an odd sized nipple. I was going to see what he had at Friendship in June, but it was canceled.

The other option is to send him the barrel and have him fit one for you and send it back.

Fleener
 
Just went through this process. Fortunately old nipple was small, threads clobbered. Drilled it out and rethreaded for larger size. Not standard but larger size available and worked fine.
 
Here's the end report.

I ordered and tried a number of 6mm and 7mm nipples. None captured the thread form.

Then, because many of the antique European percussion firearms I have handled, exhibited a thread form that was close to our 1/4"-28 nipple, I tried a Treso AMPCO 1/4"-28 nipple which is a bit "softer" than steel and greased it with Hornady's anti-seize. The AMPCO nipple picked up the thread form and "adjusted" slightly (wee deformed) to the difference between the thread pitches.

Went out immediately and shot that piece today.

Everything working perfectly.

Thank you all. What an adventure. But keep the AMPCO nipples in mind for an "adjusted fit."
 
Thanks a million for all your "fixing" techniques and ideas. One or another will put this fine, little piece back on the firing line.

This is what makes our forum so invaluable.
If u can find someone with a metric tap and die set try threading the nipple into a die. If you find the fit u are in luck if not and u can't find the thread in American size u are going to have to install a thread insert to accommodate the nipple of chose
 
15 or so years ago I blew the nipple out of my rifle. Threads were weakened when I once cross threaded it starting out 25 years prior to that. CVA Mt. Rifle, so metric nipple. A friend had a huge collection of nipples, and I recut the threads using a progression from .250x28 to a final .265x28. I have not cross threaded it since, and the threads still look just great.
 
Its likely a metric thread. Get a tap set and see which one threads in correctly. Dont force them or you may ruin the threads.
If it is German it's more than likely it is 6mm which is the same as 0BA(British Association). .236" O/D X 1mm-.0394",471/2 degrees inc angle. BA was a development of Metric threads according to my early Machinery's Handbook..1914 Edition. Don't re-tap it. Find a good local Model Engineer and Cross his palm with an amount of Silver.. Nipples are not difficult to turn & screw cut. Getting the Hole right is the most important bit.. Small hole at the top for shot guns, Small hole at the bottom for Pistols and Rifles.. Full Dimensions by PM if required.. OLD DOG..
Not that likely to find ‘metric’ threads on an old German gun like the OP has. The Swiss STARTED to develop metric threads in the late 1800s, and it took years before any standardization.
 
There were dozens of gun makers around Liege from the 1700's to today.. Several Liege cap guns I have handled have had 6 x 1mm nipple so there must have been some sort of standardisation in that area fairly early in the gun trade as there was in B'rum,Bilston,Tipton and Wolverhampton, England. The equivalent of 6BA was pretty standard in the Wolverhampton lock trade in late Flint to modern bridle screws.It must be remembered that the European gun trade was much more concentrated into specialised areas than the greater diversity of an other part of the world.. OLD DOG..
 
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