The Glock 25 and 28 are the only Glock models a civilian can legally own here in Mexico. With factory .380 ammo, they work about 99%. I mean by that to say that they will jam or misfeed or fail to extract about 1 in 100 rounds. The .380 Magazine has a "filler" built into it to move the round ahead to make up for the short overall length, but it still doesn't work perfectly.
The .380 Barrel is much thinner in O.D. than a 9 barrel, so you can't just "pop" a 9 barrel into the slide. Also, the barrel hood of the .380 is smaller in size than a normal 9 barrel hood, so it really won't fit. The locking lugs on the slide forward edge and the barrel shoulder are cut away making the pistol a sort of Blish Lock-style delayed blowback as opposed to perhaps a straight blow-back. I have seen G-25's in their factory form withstand reloads up into the high 9 +P area of power with no damage and no case bulging. I don't recommend you live your life doing this, but I've certainly seen it enough times in the last ten years. I have seen that when certain brands of Factory .380 are used that have a little more power than the standard Aguila or Federal 95 grain FMJ brands we have available here, the G-25 seems to work a little better. It's still not 100%, but it does work better. I think many of the stoppages are caused by a combination of short-slide travel caused by limp-whristing as well as a bullet underlength for the action, and slightly more powerful ammo gets the slide back far enough even if the shooter uses an English Tea-cup hold. (Interestingly enough, even fairly standard .380 factory ammo has about the same recoil out of a stock G-25 as 9 duplication loads do out of a G-25 that's been locking lugged.)
I have a Glock 25, but found it to be practically useless except as a dangerous type of "toy" in it's factory form. (They are all the rage down here, because it is all one can legally get, but it's still little more than a dangerous toy. Too big to conceal, too weak to be sure of, and it WILL fail on you at least once out of 100 rounds at the best of times -- often more. That .980 overall length of the .380 cartridge is just too short for the action to work 100% of the time.)
However, all that said and done, if you buy a normal unmarked G-19 slide and get yourself a G-19 barrel you have a G-19 as the frame is the same. Except, that would be illegal, because the 9 is VERBOTTEN. So, get yourself a G-19 barrel without a chamber and put a .380 chamber into it -- preferably with a 9 m.m lead in. You can then load 125 to 130 grain bullets "seated long" into the .380 case. You can load it up pretty high. A 130 grain lead bullet at 1,100 fps is no problem. With perhaps a bit of extractor tuning - or perhaps not - for the slightly different rim, reliability goes up to 99.999 % with the longer loaded cases out of -- properly remarked -- 9 m.m. magazines.
Before someone accuses me of delinquency with the .380 casing, let me state I've fired over 30,000 rounds of the particular load with no particular damage to my "hyper 25", and many other local shooters are playing with the same product. The .380 case is very strong. The law says she's got to be .380 and she is .380. The "loaded long" case stops it from entering a normal .380 magazine (although it could be hand-inserted into a chamber if one were silly enough to want to do it, I suppose). This conversion takes an unlocked G-25 and turns it into a G-25 with locking lugs. Factory .380 ammo will not even start to unlock the piece with normal G-19 mainsprings installed.
Done up thus, the G-25 is useful, as it's about as powerful as any other G-19 out there and also works about as well. A G-34 slide can be used with the "adapter piece" to adapt it to the smaller Compact Frame, and you just make up your barrel to suit, again installing the proper chamber and freebore. I see no reason to covet or desire a Glock 25 in the real world, other than it being the only thing "they" will let you have.
Otherwise, let no one start the "grass is greener over there" silliness because the G-25 can be owned here and not somewhere else. There is no reason to want one, they are not particularly reliable due to the short round and they have the power of a well-imbibed beer-drinker passing gas. Well, maybe a bit more power. I see lots of them everytime I go shooting and it saddens me that their proud owners -- because they are rather hard to get even though they are legal here because the Army does not WANT you to have one -- are so delighted to actually have one. It's like being in the Trenches of World War I with a Ross rifle while everyone else has a Lee-Enfield. Come on, get real. In it's factory form, the G-25 is a stoppage waiting to happen. And deplorably weak for it's size when it does function.
Thinking on it, it's depressing, really. But you certainly can "hot-rod" it into something if you spend the time and the money to go about doing it.
