Nipple thread sizes..

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Acker

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I'm working on the metal parts on the shotgun I posted that I'm rebuilding..Everything in good shape other than the nipples..Tops are terrible deformed..Thread is almost dead on 1/4-28,but a 1/4 -28 bolt drops right in,hole a little big..Now,I can fix the nipples and put them back in,but is there a common weird thread I can just buy to replace them? A kit with a tap?
 

bang

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1/4 28 can be mistaken for 8mm if my memory is correct. A 1/4 28 will thread but be loose. Try an 8 x 1.25mm
 

SDSmlf

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Thread is almost dead on 1/4-28,but a 1/4 -28 bolt drops right in,hole a little big.
Doesn’t sound very ‘dead on’. What makes you say it is ‘almost dead on 1/4-28’? How did you measure it? Could be metric, possibly 8mm.

Edit: Bang, didn’t see your post as I was typing.
 

Grenadier1758

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Both Track of the Wolf and Dixie Gun Works have nipples with over sized threads to install when the original threads wear out. Measure the diameter of the hole and buy a nipple large enough to fit the new threads.
 

Zonie

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8 mm is equal to .3150 inches. That's just a shade over 5/16" but no where close to a 1/4".

1/4" is equal to 6.350 mm. 6.5mm is equal to .2559" but there is no standard 6.5 mm thread.

6.0 mm is equal to .236 inches so it would be undersize in a 1/4-28 hole.

Dixie gunworks offers some nipples with oversize threads for the 1/4-28 (.250-28) thread. Among them is a .255, .260, .265 and .270 diameter thread. These are basically oversize threads to be used in damaged or worn out threads.

You might want to get a few in .255 and .260 diameter for this loose fitting shotgun nipple replacement. Here's a link to the Dixie page.

 

SDSmlf

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8 mm is equal to .3150 inches. That's just a shade over 5/16" but no where close to a 1/4".
Agree, but rereading the OP, sounds like thread may not be close to a 1/4-28.
Thread is almost dead on 1/4-28,but a 1/4 -28 bolt drops right in,hole a little big.
If a 1/4-28 bolt ‘drops right in’, an over oversized 1/4-28 nipple is not going to work. An 8x1mm thread uses a 7.1 mm tap drill. A 7.1 mm drill will result in a .279” hole, plenty of room for a 1/4-28 bolt to ‘drop right in’. The tapped hole needs to be measured and a proper fitting nipple needs to be installed. Guessing and trying various sizes until one seems to fit is silly at best, dangerous if things go wrong. If the threads are damaged, time to drill out and tap for the next larger size nipple.

If you have a machinist friend or know a gunsmith, let them measure it for you. ‘Almost dead on’ is not a unit of measurement.
 

bang

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Do yourself a favor and take it to your local LGS and get it measured.
I have a chart the list the external diameter of
6x.75mm, 0.23-0.24
8mm at 0.3-0.31
#12x28 0.2085-0.215
1/4x28, 0.2425-0.249
 

Acker

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Guys..i am a machinist..I'm just stupid about muzzleloader nipples..I was wondering what's out there as far as oversize nipples,ETC..The thread isn't worn,the nipple is just bigger than 1/4-28..I checked it with a thread gauge,it's definitely a 28 TPI thread..Guess I'll check out some metric sizes,see what I can put in there,or I'll just make a set,or fix these..
Thanks guys..
 

bang

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Track of the Wolf has some oversized nipples. Didn't see any less than 0.440 cone. Guess could be reworked. There is also the hielicoil fix.
 
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SDSmlf

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Guys..i am a machinist..I'm just stupid about muzzleloader nipples..I was wondering what's out there as far as oversize nipples,ETC..The thread isn't worn,the nipple is just bigger than 1/4-28..I checked it with a thread gauge,it's definitely a 28 TPI thread..Guess I'll check out some metric sizes,see what I can put in there,or I'll just make a set,or fix these..
Thanks guys..
Took your ‘drops right in’ to mean it didn’t engage any threads. Likely a badly worn 1/4-28. It doesn’t sound like it’s a 12-28 as some suggested, as a 12-28 has an even smaller major diameter (.216”). What size pin fits in the threaded hole now? A 1/4-28 tap drill is either a #3 (.213” diameter) or possibly a 7/32 (.218”). Once you know just how oversized the hole seems to be you can use an oversized tap to clean it up the threads (TOW for example has + .005”, .010”, ..... up to + .025” taps) and get the appropriate sized nipple.
 

Acker

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Zonie,I think you solved my problem..I've been doing a lot of crazy stuff,I JUST found my digital caliper and my SAE thread gauge,and got the time to look at it..
The thread is .360-28..It's OK,but oversize..I'm going to buy a set of .260+ .265 nipples,see which works better..Thanks guys!!
 

SDSmlf

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Zonie,I think you solved my problem..I've been doing a lot of crazy stuff,I JUST found my digital caliper and my SAE thread gauge,and got the time to look at it..
The thread is .360-28..It's OK,but oversize..I'm going to buy a set of .260+ .265 nipples,see which works better..Thanks guys!!
Guessing you mean .260-28, not .360-28? For best possible fit I would get the 1/4-28 +.015 (.265) TAP and nipple. The tap will clean up the threads for a perfect fit. This assumes that the current hole is less than .228” diameter, which is the appropriate tap drill size for the oversized thread.
 

Acker

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Guessing you mean .260-28, not .360-28? For best possible fit I would get the 1/4-28 +.015 (.265) TAP and nipple. The tap will clean up the threads for a perfect fit. This assumes that the current hole is less than .228” diameter, which is the appropriate tap drill size for the oversized thread.
Yes..Duh...Going through some nonsense,brain is oatmeal..Actually,the threads are decent,only changing them because the nipples are deformed badly..
 

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