Happy Birthday America     

I believe Track used to carry a repro of the Hawsley flask head, or something kinda like it.
I did like that one as it had a screw off base that really simplified the installation process.
I found that with the ones from Pedersoli, one had to do some careful grinding to make a spot in the nose of the horn for the gate to be able to function.  One little slip and you were through the horn.  I forger the size of the hole saw I used for that but you could cut out horn material to the point where the base of the valve would just fit onto the horn with only a tiny bit of file work.  I would epoxy the valve onto the horn then drill and tap two holes for little brass screws to make sure the valve installation was permanent.
Gee, I used to have a lot of fun messing around with silly little projects like that in between my regular production work.  If I would have known that the Hawsley style flask head was discontinued, I would have kept the last one I made, it was really beautiful.
John

Aren't damaged flasks the usual source for flask heads for powder horns? 

The Hawksley brothers founded G&JW Hawksley LTD in 1840--which puts them post-dating the rendezvous era.  By ~1845-1850, they started showing up on horns (similar to KDubs above): some of this was folks blending the head from a damaged flask with the body of a powder horn, but some of it appears to have been original work.  Their father, John Hawksley, was a horn merchant. 

Most of the "blended" horns seem to date after 1850, judging by the makers' marks.  So while too late for the beaver trade, they fall right in to the middle buffalo hide trade (sometime we should have a good discussion here on the actual buff hide trade, rather than just the "Glory Days of the Sharps Rifle").  Even as late horns, I've always thought they were incredibly cool.  I used to have one, and it was a joy to use. 

I've got a (repro) flask with a Hawksley-pattern head on it, adjustable from 2 1/2, 2 3/4, 3, 3 1/4 drams.  I got it with the intent of robbing the head, but kept having people tell me it was "worth more as a flask" and that I'd stumble across a head eventually.  Well, I haven't seen a bare flask head (or damaged flask) in the 5 years I've been looking, and the flask has been for sale for 2 years with nary a nibble.  Sometime this summer, I'll get one made.

Of course then I'll have to get a .54 caliber Mississippi and sporterize it, but sacrifices must be made at times. 

Got the dinky little horn done (seems I'd also forgot to pin the butt plug in place--oops!), replaced the staple on the b uff horn and got it done, even carved spout plugs. 

Removing a properly-installed staple is a bit hairy.  On that horn there was 3/8" of each leg protruding inside the horn, and I bent them over while the horn was still open on both ends.  I wound up cutting the staples flush with the outside of the horn, then  punching them through.  A little shaking and they were out.  Replacement was a different matter. . . I made a new staple from a brass cotter pin I had laying around (half-round wire), filed the ends to fit the holes, and heated the staple red hot to anneal it.  While it was hot (but not red hot) I pressed it into place.  As the pins began protruding through the horn, I started bending them over.  Had to make a tool for that.  I took a #2 Phillips screwdriver and extended one of the cuts at the tip back about 1/2" using a file.  Lined up with the legs of the staple when inserted into the spout, it caught them and bent them the direction I wanted. 

I'm not happy with the spout plugs, but I never am.  I've examined (and have notes on) >3,000 horns with a history of use in the trans-Mississippi west.  More than half were missing the spout plug, and who knows when the remaining plugs were added to the horn?  Some might be original, but how could you tell?  I saw some horns in Europe that seem to have been curated close to the time of use and probably had the original--or at least, contemporary--plugs in them, but that is about it. 

The little horn now has a poplar spout plug carved kinda like a fiddle peg.  The buffalo horn has a plug--also poplar--carved as a section of a cone.  I may trash one or both, and start over. 

The third horn I was working on is officially completely and totally dead.  Nice horn, but while shaping the spout I noticed a "crack".  After another hour it was clear it was a de-lamination: too large to salvage as a powder horn.  It is otherwise a nice horn and may wind up becoming a cup or run horn.  It is probably too thin to get chopped up and turned into rings for a banded horn. 

Started work earlier this week on horn #4.  This one is a copy (based on my notes) of a bison horn I saw in a collection in the UK.