Here's another GURPS conundrum. The Anaconda and the 629 weigh almost the same. The ammo weighs the same.
.44 does more damage and goes farther, but needs a higher ST and has a stiffer recoil penalty. It might load slower, but I think that's an unresolved bit of errata in my tables. Price comes out in the wash and legality class is identical.
3d-2 pi+ on an unarmored body hit does 1-24 points of damage with an average of 12.
3d+2 pi+ on the same target does 7-30 points with an average of 18.
Let's assume a skill of 14 with Guns/TL7 (Pistol) and a ST 11.
The penalties for shooting at the 1/2D ranges are -11 for .45 and -13 for .44. This just isn't going to come up unless your GM hands out the points like Monte Hall. A skill 14 doesn't even get a roll to hit past 150 yards anyways!
At 10 yards, it's a -4 to hit. If you aim, +2. If you fire double action -1. Net 11.
With the Anaconda a roll of 11 hits one round, 8 hits two and a 5 hits three. 62.5%, 25.962% and 4.63% respectively.
With the Smith, a roll of 11 hits one round, 7 hits two and a 3 hits three. 62.5%, 16.204% and 0.436%.
Since the average to hit roll is going to be 10, both guns waste two rounds on average! However, the .45 is 50% more likely to land two shots and ten times as likely to land three.
Put another way... Out of 300 rounds fired, .45 will land 86 rounds and .44 will land 77. Using the average damage that means 1,032 points for .45 and 1,386 for .44.
If you have a ST 10 like most people (but not most adventurers) you've an additional -1 for being a point short. That changes your chances to hit a bit, needing a 10, 6 and 2 or 50%, 9.259% and 0%. That should land you 58 hits though for an average of 1,044! Still better than .45 huh?
What you do get with .45 Colt is the ability to use ammo all the way from 1873. .44 Magnum can chamber and fire .44 Special from 1907 (with reduced damage and range but also reduced recoil) or .44 Russian from 1870 (with even more reduction in range).