Major 2,
The backstrap is yours ... but PM me a good address to send it to
That being said, there are a number of factors going on ...
First, the gun is only used for reenactment, and will probably never see anything but blanks fired through it ... (in fact, that is the weapon in my profile. Most of the time (About 95%) it just sits in my holster.
On over a year doing reenactments, I have never had ONE question about the pistol except wether it was real or not .... *S*
Secondly, I think my pistol was possibly assembled at the factory from spare parts left over at the end of a run ... and they put bored-out-to-.44-cal. '51 cylinders on an 1860 Colt and called it a '51 Colt because of the engravings on the cylinder ... I believe the 1860s had a bigger grip, which would account for the square back grip not fitting.
The squareback frame could also be from a Model '47, again explaining why it is too small.
I dunno, and don't have a local BP gunsmith I trust enough to find out ... 'cause if I do own an oddity, I don't want to change it in any way ... so I have this conundrum of my own making ...
I keep erasing this paragraph, so I hope that this can get out ...
Major 2, you are welcome to the squareback trigger guard ...send me a PM with a good address ... althought I just looked where I though it was and could not find it ... so it may take a while to send ....