Hi Power Longevity
A frequent question centers itself on how long a Hi Power will "last". I've seen various estimates that range from 30K to about 50K rounds with barrels needing replacement at about 20 to 25K full-house rounds. I will relate what I've seen long-term.
How long a Hi Power will last depends on a number of factors, not just the round count:
Has the recoil spring been changed? I routinely change these about every 1000 to 1200 rounds fired. I do not know if this is "early" or about right. It has worked for me. When I've been using primarily hot handloads or +P ammunition, I do it at about 1K rounds. Recoil springs do not have an infinite life and failure to change them allows the slide's rearward velocity to exceed what the gun is designed to withstand and allows excessive battering of the frame. I think it can also contribute to rounding of the locking lugs, as the unlocking process will be sped up. It is possible that with a stiff magazine spring, one might start getting failures to feed if the slide's forward movement is not fast enough to strip a loaded round and push it from the magazine, up the ramp and into the chamber. Heavy use with a weakened recoil spring can also lead to breakage in the Hi Power barrel cam, the flat bar of metal that the barrel rests on. The is a major fix if breakage occurs.
Both of the rounds shown are from Corbon. The left is their 100-gr. PowRball. The cartridge on the right is a 115-gr. JHP. Both are +P and both are maximum effort loads. This ammunition should not be used on a steady basis w/o a heavier recoil spring being used in my experience. A modest amount of shooting in the unaltered gun is probably OK.
What type of ammunition has been used? You're probably fine with expectations of a long-lived Hi Power using but factory springs and standard ammunition. I do think the gun is best served with the 18.5-lb recoil spring and buff in any instance where at least standard pressure ammo's being used. If you intend to use the warmer loads, I believe the heavier spring/buff is essential for extended shooting over years. I do not recommend steel-cased ammunition for the Hi Power as it was not designed for such and have some reports in where some extractors appear to have been damaged from constant use of this type of ammo.
Has the mainspring been lightened? The mainspring (hammer spring) comes from the factory at 32-lbs. Not considered by some, reducing it has the same effect as reducing the recoil spring in that there's not as much resistance to the slide's rearward movement. That said, I have a couple of older Hi Powers that came with the lighter mainsprings and they're working fine after decades of use. (I do use slightly stronger recoil springs in them.) The mainspring is lightened in most cases in the quest for a better trigger pull. The most common change seems to be from 32 to 26-lbs. I would not go below that.
Has a stronger recoil spring been used? Factory standard is a conventional 17-lb. recoil spring in 9mm and a 20-lb. in .40 S&W. I think the forty spring is fine like it is, but prefer to go up from the 17 in 9mm to the 18.5-lb. This does not make the gun's slide much harder to operate and it has worked fine for me with both standard pressure and +P ammunition. I believe it reduces battering when the slide smacks the frame in shooting. I have not noticed any problems with the faster forward slide momentum, i.e., causing the hammer to follow to half-cock if the sear/hammer engagement is correct. If a trigger-job is done on a Hi Power using a 17-lb. recoil, it is possible that the hammer following will occur if the heavier recoil spring is used. This can be corrected, but is a nuisance. I suggest that if a trigger job's in a Hi Power's future that it is done with the heavier recoil spring. Going back to the factory standard shouldn't affect it and you're covered whichever weight recoil spring you wind up choosing.
Have recoil buffers been used? While there is some controversy amongst shooters concerning how much heavier recoil springs might help a gun's useful life, there seems to be more over the use of buffers. Some opine that "if the factory didn't see fit to use them (or the heavier recoil spring), they must not do anything."
Others fear that malfunctions could result.
I have had good luck with the one type of buffer I use. It is from Buffer Technology and is merely a polymer "pad" that surrounds the recoil spring. There's information on this elsewhere on this site including "problems" and how to install correctly, etc. I use these in all my Hi Powers and believe that they do prevent slide battering. The buffers get pretty chewed up and I believe that their use and replacement extends Hi Power longevity particularly with hot loads.
Does the Hi Power have a cast or forged frame? Frame types are also discussed elsewhere on this site. After several years of hard use, I truly believe that the cast frame Hi Powers are better suited for extensive shooting with hot ammo. The earlier traditional Hi Powers are fine with standard velocity ammunition, but the cast frame pistol came into existence because the forged frame .40 Hi Powers simply didn't hold up beyond approximately 2500 rounds. The 9mm frames were cast soon thereafter as well, probably as a cost reduction to FN. Why forge the same frame in 9mm when it's being cast for use with the forty? If using a forged frame Hi Power, I would recommend the use of both the heavier recoil spring and the buffer. Shooting some of the hot ammo is not going to hurt the forged frame Hi Powers, but steady use will loosen them up more quickly and accelerate wear in my experience.
This Hi Power was manufactured in '71 and has been shot ever since. The hard chrome has reduced some wear I suspect, but it's been equipped with a Wolff 18.5-lb. recoil spring that's changed about every thousand to twelve hundred rounds. I also use a buffer in this pistol.
Has the Hi Power been regularly cleaned? When any firearm is shot, debris winds up in the gun. In the case of the Hi Power, this can be in the slide rails, around the barrel, under the feed ramp, etc. Just as grit can score a car's piston, so can it accelerate wear when between two moving pieces of steel. In any event, cleaning cannot hurt the gun, only help it.
I recommend cleaning the barrel at the end of each range session. This keeps accumulations of gilding metal from being deposited in the bore such that it is much harder to remove. Keep the barrel clean and without the cleaning rod rubbing on the bore. I do not use stainless steel brushes. I suggest using only brass bristle brushes for cleaning.
General wisdom has it that cast or lead bullets are easier on the barrel than jacketed. I tend to agree with this, but in my experience jacketed ammunition provides best accuracy with the Hi Power's 1:10 twist. I do think that barrel wear and erosion is minimized when shooting is not primarily rapid-fire in long strings. In other words, don't get the barrel so hot it cannot be touched.
Lubricate the gun after cleaning. I put a drop or two of oil or grease on the lugs, around the barrel where it comes in contact with the bushing and on the cam. A drop or two in the slide rails keeps it moving freely.
These techniques have worked well for me for over thirty years. I offer them only as helpful suggestions. The individual Hi Power owner is certainly free to do that they think is best and forget that which they believe to be unnecessary.
There is no magic round count at which the Hi Power just stops working or turns to dust. Unless truly dangerously hot loads are used, the Hi Power's not going to explode or just come apart. What happens is that they wear such that tolerances become looser and there may be some small parts breakage.
Even with the use of light or standard loads, somewhere along the line, a small part might break or need replacement. This does not mean that the gun's worn out. Some parts will simply last longer than others with the life span being determined by the alloy used or tolerances held when that particular part was produced.
Two of my Hi Powers were made in the early '70's and both are going strong today after literally a lifetime of serious use. I've followed the suggestions mentioned here. Having compared the frame types by actual long-term shooting, I now shoot primarily standard pressure loads in the forged frame pistols.
Of everything mentioned I believe that recoil spring replacement as suggested, cleaning/lubing, and not reducing the mainspring weight are the most important.