Agree, would help at least to upright the photo - my tablet's gyro kept quickly correcting it back it to its wrong position! But, from what I could tell, 1900-1920ish given the rounded triggerguard--unless I mis-saw, entirely possible--that's tell-tale for that period, and if that's the case it's (as a general rule) that would be before they got rid of the rounded cylinder/flute chamfer which this appears not to have...so, replacement very late 1st Gen (late 1920s-1930s?) or 2nd Gen (1956-1975) cylinder--and, if so, which looks then to be "aged" to match the rest....or the whole gun antiqued along with the "new" cylinder....which was very popular and fine unless the seller/trader is claiming "originality." My guess. If some or all of the above done and completely operational, $1,000-1,200. If I've missed on these aspects and all original, at least $ 1,800- 2,200...or more, and a letter of provenance should be ordered from Colt. The letter not worth it if significant mods done.