Pre-Mk III guns are on the Colt E/I frame, which is the Python frame/internals.

About the E/I frame in general. There are early and late variations with some changes (same can be said about most any S&W). The change from the Army Special to Official Police is where you see the most up to date version of that action that includes a hammer block internal safety. Pre-War double actions are pretty darned stiff as Colt put a premium on single action shooting, and fast lock time. Prior to WW2 the focus was on ultimate accuracy rather than speed shooting. The old saying in motor racing "Win on Sunday, sell on Monday" held true for revolvers back then. Since Colt held most of the bullseye records, the single action accuracy was highly emphasized. Eventually, the market woudl change and Colt reacted a bit slow, allowing S&W to just zip right past them and never look back.

E/I frames are VERY stout, VERY strong medium frame revolvers, more akin to a S&W L frame than a S&W K frame. Ergonomics are very different from S&W's and that's a deal breaker for people who grew up on S&W's. The reach to the trigger is noticeably longer, which works well for me personally, but not everyone. In fact, it was a bit of an adjustment at first for me, but after I got used to it, I found I actually shoot my Colts better than I shoot my S&W's; which was a BIG surprise to me.

Official Police is a VERY heavy duty .38 Special and quite capable of handling even .38-44 High Speed level pressures. In short, good luck trying to wear one out. They are a fixed sight service type revolver. Pre-war versions are most often found with a 6" barrel, with 4.5" as the next most common. But they were made in most any barrel length the customer wanted. Post-War guns are typically 4" & 5".

Officers is Colt's premier target revolver, and let me tell you, they are freaking wicked accurate. These were hand assembled, and if one ever came back to the factory for repair, the man who assembled the revolver has to fix it on his own time after hours...so they tend to be really good. The Officers has set more bullseye records than most any other DA revolver made, with the .38 Special New Service a close second. Pre-War guns are very sexy to my eye, but many find the adjustable sights (rear adjustable for windage, front for elevation) a little annoying. Mine is a target gun, not a field gun. Personally I think the Pre-War Officers have a much nicer sight picture than the Post-War. Post-War Colt added heavy barrels and a fully adjustable rear sight. They are easier to work with, but the really heavy barrel guns are Gawd-Awful ugly...but they shoot like nothing else.

Trooper (pre-Mk III) is the "deluxe" version of the Official Police, most often found in .357 magnum, but can also be found in .38 special. These are just fantastic .357's, extremely durable, very accurate, but DA's are still a touch stiff. Most often it just takes spring adjustments to bring the DA pull down, as you rarely need to actually take a stone to the inside of a E/I frame Colt.

Python of course is Colt's flagship revolver. The new ones are better than the old ones, but the old ones are very good, and aesthetically much better finished.

ALL of Colt's E/I frames are absolute tack drivers, and its the rare shooter who can actually out-shoot his Colt DA revolver.

I currently own a 1979 Python, and 1937 Officers Model Target. I also have an Official Police/Commando that I'm building from a box of parts I picked up at a gun show, so I'll have 3 E/I frame Colts soon.

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