Old Pedersoli KY rifle vent size.

[Paul from KY]

I have converted a Pedersoli Kentucky rifle made back in 1974 (date code XXX) from percussion to flint but I can't find a vent liner with the correct thread.  Supposedly it is 8-1.25 but the thread is much more fine, like 5/16 32 thread. Has anyone else encountered this problem? 

[TDM]

You could talk to Dixie Gun Works or Muzzleloader Supply House to find a match if you can determine the actual thread pattern. If not, drill it out to the next size up and retap.

[taterbug]

if you don't have access to a thread pitch gage, you can take the drum into a local hardware store.  Maybe not a big box store, a local mom and pop type would be best. 

You can compare the old drum threads with some of the selection of bolts they have.  Lay a bolt that you think is close, on top of the drum with the threads trying to mesh with each other.  I have to hold it up to the lights to see.  If you see light somewhere between the bolt threads and drum threads, or if the threads don't mesh perfectly, try another bolt.

Once you find something that you think fits, verify it with the nut that fits the bolt you picked out, and try the drum in that nut.  They usually have all common SAE and metric sizes.  You might not buy a single bolt, but I usually try to find something I can buy just for the convenience of using the store. 

[Grischi]

Maybe it's M8 x 1,0
At least available in Germany, but the prices are high.

https://www.artax-vorderlader.de/vorderlader-zubehoer/zuendlochschraube-berylliumkupfer-gehaertet-m8-x-1-feingewinde-fuer-steinschloss-vorderlader.html

https://www.stifters-gunflints.de/product_info.php?info=p1165_zuendlocheinsatz-m8x1-0mm-aus-edelstahl-mit-konischem--9-6-mm-rand.html

Christian

[Seth Isaacson]

if you don't have access to a thread pitch gage, you can take the drum into a local hardware store.  Maybe not a big box store, a local mom and pop type would be best. 

You can compare the old drum threads with some of the selection of bolts they have.  Lay a bolt that you think is close, on top of the drum with the threads trying to mesh with each other.  I have to hold it up to the lights to see.  If you see light somewhere between the bolt threads and drum threads, or if the threads don't mesh perfectly, try another bolt.

Once you find something that you think fits, verify it with the nut that fits the bolt you picked out, and try the drum in that nut.  They usually have all common SAE and metric sizes.  You might not buy a single bolt, but I usually try to find something I can buy just for the convenience of using the store.

A lot of stores have a display with nuts and bolts mounted on them that you can check threads on like this which make it even easier:

[Paul from KY]

Seth, I have a thread index board almost exactly like that.  Evidently the Italian bp gun makers used some machine screw sizes and thread pitches that are unique. Recently manufactured Pedersoli KY rifles use a different size, readily available vent liner/percussion drum from those built in the 1970s.  Anyhow, I drilled and threaded the vent hole up to 3/8-24 and made a vent liner out of an old bolt I had laying around.

[Leatherbark]

From Dixie Gun Works Catalog

NPO835   5/16 x 20 vent. Squared shoulders. Works on many Pedersoli made firearms. (equiv. to 8mm x 1.25).....$4.95
NP0706    5/16 x 24 vent. Dixie Cub/Pennsylvania rifles....$4.95

My Blue Ridge I had around 2002 used the 5/16 x 20 vent.  Still have one IIRC.  But its too late now