A little info regarding .40 HiPowers:
Browning was slow to come out with a .40 when everyone else rushed theirs out. Writers at the time said Browning took their time to get it right rather than just dropping in a .40 barrel, but my theory is Browning simply showed the HiPower their usual lack of attention and got it done when they got it done.
Yes, it always bothered me that the HiPower got a page or less coverage in a catalog with six pages of socks.
There were in fact some changes beyond the caliber of barrel. The slide on a .40 BHP is wider and heavier. If you look at the left side of a .40 slide, there is a relief cut forward of the slide stop. They used the same slide stop on the 9mm and .40, so the .40 slide had to be thinned in that area to 9mm width to clear it.
Some makers who used the same slide as their 9s, only cutting the breech face to suit, didn’t have good luck. The heavier slide of the .40 BHP seems to have helped.
I don’t know what the slide weight difference is (I’m not home now) but if used to the 9mm, a .40 BHP is clearly different feeling. It’s more top heavy, as you’d expect. The 9mm slide is so slim and trim that any change was going to noticeable. What a person thinks depends on what they’re coming from. If you carry a 1911, you might think how trim a .40 BHP is. Most of us 9mm HiPower users thought it felt “wrong”.
Another change that happened around this time was a change from milled to cast frames. The cast frames are harder than the milled. I’ve read that these harder cast frames were created FOR the .40 version. Others have said that was a coincidence, and FN/Browning had to replace tooling around that time anyway so went to a casting. I do know the cast slides are harder because tightening the frame-to-alide fit by “peening” the frame rails of a milled frame is only a temporary tightening.
The cast frames are identifiable by looking at the very bottom, behind the mag well opening. Cast frames have fore-aft grooves like serrations.
The other big change on the .40 was adding another recoil lug to the slide and barrel. The HiPowers use lugs similar to the 1911 to join the barrel and slide during initial recoil. The 9mm guns have two barrel lugs and corresponding slide grooves. The .40s had a third.
As a side note, some companies made a 9mm barrel with the third lug that would drop into a .40 slide. Some people did this as insurance to have a (potentially) more durable 9mm gun. It would presumably be softer shooting also.
When I sent one off for full whiz-bang custom treatment, I gave a fair amount of thought to sending my .40 and doing this, but sent a 9mm instead.
Back to how they “feel”. Obviously gun feel is an individual opinion. While the .40 BHP feels odd to me because I’m used to the 9mm, I also think it feels trimmer than a 1911. I might even go so far as to say the .40 BHP fits perfectly in the middle.
I want to make sure and say this: My .40 BHP is the best shooting factory-stock .40 handgun I’ve shot. By this I mean recoil impulse and accuracy. USPSA Limited class guns built on 1911s do better on both counts, but they should.
I have heard this enough times from owners to think it’s not a fluke.
As much as I tried, I could not warm up to the .40 cartridge. I owned and tried several, trying to like it. A CZ75B came close, but the only .40 I’ve kept is the BHP. I still don’t like the .40 cartridge, so I don’t carry it and haven’t even shot it for years. I couldn’t let it go because I liked how it shot. It’s not my favorite HiPower, but it’s my favorite.40.