Odd percussion nipple

[kelvinator]

So this is for my Allen FA Santa Fe Hawken... it has standard 1/4-28 threads, I have several nipples left over from a TC Renegade and they fit, well, they will thread in just fine anyway.
The nipple that came with the gun is what I'm trying to identify, and it is most likely not original.
It is longer than any rifle nipples I can find listed at TOW at .675" overall length, most are .635".
The thread journal is .205" long and the cone is .470" long.
Base diameter seems pretty standard at .310" ish.
Basically, it's a good .040" longer in the cone than anything I can find.
I did find some original Ithaca hawken nipples at Numrich and figured they would be correct but they did not list any dimensions, so I took a chance and ordered a few.
They thread in just fine but are about .050" shorter than what I'm hoping to find.
I'm sure the shorter nipples will work okay , but geometry with the hammer face is perfect with the longer nipple, and just a little off with the shorter ones.
The nipple that came with the gun is working fine, I would just like to have a couple back-up spares if I can find some.
Any ideas?

 

[kelvinator]

I also have a 12 gauge Navy Arms SxS percussion shotgun of mid 80's vintage, so for grins I took a close look at the nipples on it, which I believe to be original, and low and behold, they are the same as the one in my SF Hawken... well, closer than anything else Iv'e seen.
Must be an Italian thing.
Surely there is something available out there that matches these?
Do I need to search for shotgun nipples?
Are shotgun nipples typically any different from rifle nipples?

 

[kelvinator]

Here is a pic for comparison.
Left to right.
1.Navy Arms shotgun. 2.Allen FA S.F. Hawken. 3.Ithaca Hawken from Numrich. 4.Generic TC Renegade.