H.T. JIM 

Perhaps not "widely."  Perhaps "some" conversions were made by local smiths in 45 Henry Flat.  Not by Colt.  Colt only converted to .38 Colt and .44 colt (centerfire).  The first we see of Colt chambering (that I remember) other than 44 Colt was the Colt Open Top.  The Open Top Chambering was actually intended for Colt's proprietary cartridge, the 45 Stetson, which was basically a 44 Henry Flat with a different head stamp.  Colt did that because the original chambering for the 1866 was the 44 Henry Flat and with Colt and Winchester not being Bosom Buddies, yet the market place clamoring for a companion hand gun to the 1866, Colt responded with the Open Top, hence,  the Colt proprietary (but interchangeable) 44 Stetson.  Such a tangled web business weaves.

I could be all wet as I haven't plunged deeply into this history for a long long time.  But atz as I remember reading it.  And, since the 44 Henry Flat/44 Stetson were such short cartridges, I have always tried to give that historic impression using 44 Russian or C45S or 45 Squirt cartridges.  Fun Stuff.

O estimable crafter of pine boxes,

It's probably me who's all wet.  Now that I think about it, I don't have any knowledge of Colt factory conversions in the Henry cartridge.  I recall seeing an 1860 that I believe was converted to the Henry, but now that I think about it, I think it must have been a gunsmith special because I believe it required removing the barrel to reload.

Colt did, I understand, produce some SAAs in .44 Henry, but of course those aren't conversions.

Is the .45 Henry Flat different from the .44 Henry Flat?

Oh Krap 

Type 0.  Corrected it I did.  45 Henry Flat should have (now does) read 44 Henry Flat.

Mumble mumble mumble.

And I must chime in with a correction about the 45 Colt... It's "rim" diameter or thickness has not changed since introduction... what has changed is the addition of an extractor groove. 

Quote from: Professor Marvel on December 14, 2023, 10:15:42 PMAh My Dear Coffin....
As always, there are a few rare exceptions....

This one being my favorite: the Remington Revolving Rifle!

Snip...........
" The Remington Revolving Rifle was initially produced in percussion models in two basic sizes, related to caliber. Both of these sizes were later offered in rimfire cartridge models as well. These initial sizes were the .36 cal percussion cap & ball, and the .44 cal percussion cap & ball. The cartridge conversions later offered were the .38 long rimfire and the .46 rimfire."

There were also occasional field conversions, at least one of which was found in .45 colt.

Please see the excellent article from the Remington Society by Mike Strietbeck
https://www.remingtonsociety.org/a-study-of-remington-revolving-rifles/

The percussion rifles were available as early as Dec,1865, the .38 rimfire and .46 rimfire cartridge rifles were shown in the
1877 catalogue.

Please see the article for an interesting nickel version in .45 colt.

The advantage?
+ Low cost  (starting at ~ $25 ),
+ light weight , ~ 6 lbs ,
+ ability to shoot cartridges -or- and loose powder and ball
+ compatible with your remington revolver
+ simple to fix for any sixgun mechanic

Disadvantage?
Only 5 or 6 round
Oddball cartridge
Slow reload

Not that many were made or sold, and like the 1858 revolver it was based upon it slowly faded away except in the hands and minds
Of excentrics like myself....

Yhs
Prf mumbles

Thanks for finding that article.  The formatting of it kind of makes my eyes bleed but I did find the one in .45 colt that you mentioned.  Am I correct that it appears to be the two piece cylinder type?

Quote from: 9245 on Yesterday at 08:24:35 AM... The formatting of it kind of makes my eyes bleed ...

I don't know what that text looks like on a phone, but on my laptop I copied the text and pasted it into a text file (Notepad) and it made it super easy to read.

It's pretty painful on a phone.  A lot of it's in two columns only a few words wide.  Great idea about copy-pasting.  And very interesting article, as I recall.

If you are considering participating in NCOWS 9245, the .45 Cowboy Special is not on the approved list.

Quote from: River City John on Yesterday at 12:02:40 PMIf you are considering participating in NCOWS 9245, the .45 Cowboy Special is not on the approved list.

My current idea is straight 45 colt as I have found period examples of it now in both  the New Model Army and the Revolving Carbine (see above).  Both appear to be gunsmith examples rather than factory, but they are now confirmed to have existed in at least one example.  So it would seem that the revolving carbine in .45 Colt is my answer, sucks for capacity and reload but historically correct at least.  Plus light and zero chance of short stroking.

  9245

I, unfortunately, am unable to speak for NCOWS, but you will find, again, unfortunately, Revolving Carbines are NOT legal for SASS/CAS.  May be fun toys for plinking but not acceptable for SASS.

Quote from: Coffinmaker on Today at 08:34:47 AM 9245

I, unfortunately, am unable to speak for NCOWS, but you will find, again, unfortunately, Revolving Carbines are NOT legal for SASS/CAS.  May be fun toys for plinking but not acceptable for SASS.

Any idea what the justification for that is?

  SURE!!

First, you have to understand, SASS is a privately owned organization.  In the beginning, there was a group of guys who wanted to play a GAME.  They called themselves "The Wild Bunch."  "They" wrote the rules. Their initial rule for Rifles specified the GAME would be played with LEVER ACTION or PUMP ACTION rifles of the period with exposed hammers.  That lever/pump action has never changed.  Also, SASS is still a privately owned organization.  They DO NOT need JUSTIFICATION.  They (SASS) decide(d) the rules and we play by them.  And since we are talking about RULES > >

ARE YOU EVER GOING TO READ THE RULES??  It is fairly obvious, to date,  you haven't bothered.