A very common question amongst Hi Power aficionados is, "Which is the best model as well as, "Are old Hi Powers better than new ones?"
So, which is best?
In my opinion, it depends on what parameters you use to define "best."
If you are really into very nicely blued Hi Powers of the classic look, most agree that the T-Series sits at the pinnacle of fit and finish. These also had the traditional ring hammer associated with the Hi Power by purist. Commercial Hi Powers made in the '70's are also nicely finished, but came with spur hammers, something that some did not care for. Until the advent of the Mk II in the '80's, Hi Powers all had feed ramps that were "humped" and many were pretty picky about what JHP they would feed reliably…or at all!
In the '80's, the Mk II hit the stage and deviated from the classic fixed sight Hi Power in its higher visibility fixed sights as well as its extended, ambidextrous thumb safety levers. It also had a narrow full-length rib atop the slide. The frame was forged like the older Hi Powers, but the finish could have very well caused major heart palpitations for those preferring polished blue finishes. Gone were the checkered walnut grips and in their place sat black, checkered nylon ones with thumb rests! The earlier production runs did not have the internal firing pin safety common the practically all of the soon to come Mk III pistols sold in the US.
In the late '80's, FN produced the Mk III. Imported by Browning, this version of the Hi Power initially had a forged frame and the gun retained not only the stocks, but also the extended thumb safety levers. Both the Mk II and the Mk III came with the now common spur hammer. The Mk III did not retain the rib on the slide and the fixed sights were larger and both front and rear dovetailed into the slide. Every Mk III that I've seen sold in the US came with the internal firing pin safety. These pistols' slide and frames were finished in a baked epoxy finish that has varied from somewhat dull to downright shiny black. Regardless, Browning calls this a "matte" finish. The shape of the ejection port was also changed to a more square one very similar to that of the 1911. This was done to increase the metal present at the lower rear of the port to reduce the chances of the slide cracking under extremely heavy use with stout loads.
With the introduction of the forty-caliber Hi Power, a change was made from forged to quality cast frames. Some gasped in horror at this. It was reportedly done, as the frame was stronger than the forged. It has been reported that after about 2500 rounds of forty-caliber ammo, the forged frames would warp. The cast ones did not and soon both the forty and 9mm versions were available only with cast frames, probably a manufacturing cost-cutting measure. Contrary to what some have reported, the slides on Hi Powers have never been cast. They continue to be forged to this day. Because the frames are harder, current Hi Power slides are tougher as they are heat-treated to a higher level than was possible with the softer forged frames.
Using the Mk III "chassis," several cataloged versions of the Hi Power exist today and probably some with specific special modifications for certain military or intelligence services throughout the world. In this country, we see:
Mk III: Described above, this version is available in 9mm and .40 S&W.
Standard: This is a Mk III in all aspects except that it has a bright blue finish and the traditional checkered walnut stocks.
Practical: This is a basic Mk III but with a hard chromed frame. The slide stop and safety levers are hard chromed as well. I have seen one with a gold-plated trigger, but most are hard chromed. The front sight on the fixed sight version is more sloping than that of the Mk III and the gun comes with Pachmayr "Signature" grips. The gun is offered with fixed or adjustable sights as well.
Capitan: I have only seen these in blue finishes and with walnut stocks. Their main difference is in the tangent rear sight.
While some of these models are offered with adjustable sights, fixed are what's usually seen.
So which is best?
If you intend only to shoot standard pressure FMJ ammunition, take your pick. All will hold up to much more shooting than done by most users. If you want to shoot JHP ammo in your classic Hi Power, it will need to be of a rounded ogive, mimicking FMJ. I'd shoot a limited amount of +P in these guns, if any. To be reliable with a wide range of expanding ammunition, these guns will usually need their feed ramps "throated." Any of the models listed will handle ball ammo without fuss.
Should you want to shoot JHP ammunition with the gun out of the box, the best bet is to go with either a Mk II or Mk III, but if you cannot abide cast frames, you'll need to go with either a Mk II or early production Mk III. If you cannot stand the internal firing pin safety, you're back to either an early Mk II or a Mk III sold outside the US as some did not have the internal firing pin safety at the request of the purchasers. The only one I know of for sure is Israel. However, these had the small, single-side classic thumb safety at their request as well.
If you use hotter loads primarily, I'd suggest going with your choice in the cast frame Mk III or variants. Should you opt for the Practical, be advised that the factory ring hammer frequent bites the hand that shoots it and in my experience, more than the spur hammers.
While I've owned commercial Hi Powers from the '70's that had good trigger pulls, I've also owned some that were pretty lousy until a trigger job was performed. This has not gotten better in recent years and the lousy trigger on most Hi Powers is a common complaint. The magazine "safety" has unfortunately managed to be retained on each and every version of the Hi Power sold in the US. (FWIW, there is no "Mk I Browning Hi Power". They did sometimes have model names such as "Vigilant" or "Sport" but no "Mk I". I do seem to recall the Canadian Inglis Hi Power have a Mk I model.)
In most cases, a trigger job by a competent gunsmith is required to wring the most out of these pistols.
Finally, should you prefer the forty-caliber, your options are limited to versions of the Mk III and the gun will have a cast frame.
Look at these differences and similarities and decide which is best with regard to what you prefer.