I own a number of .380 ACP handguns, mostly because I like them, not so much because I advocate carrying them.
I do however carry one as a back up from time to time and here are my observations on various models:
Kimber Micro
My Kimber Micro has been extremely reliable. I've put in the neighborhood of a 1000 rounds through it in the course of breaking it in and periodically expending aging carry ammo through ot for practice and it's experienced only 1 failure with my carry ammo. That's acceptable reliability for a semi-auto pistol.
My carry ammo uses a Hornady 90 gr XTP. The XTP series bullets are designed for moderate expansion and good penetration and they are a good choice in a marginal caliber like the .380 ACP. The 90 gr XTP will produce moderate expansion (a mushroom rather than the multiple spider legged looking expansion) and 12" of penetration, but the velocity window where they'll give that performance is narrow.
The positives are light weight, but with a felt recoil similar to the 30 oz all steel PPK/S, given the locked breech recoil system spreading the recoil out over a bit longer period of time. It doesn't feel as sharp as a blow back operated .380 pistol, even though the actual recoil numbers are higher in a lighter weight pistol.
The negative with the Kimber Micro is the short 2.75" barrel has difficulty driving a 90 gr XTP at the 1000-1050 fps it needs to expand with near 100% reliably in a heavy clothing test. You need to be careful in your load selection and chrono your loads.
An average of around 970 fps has been the best I've measured with a factory 90 gr XTP load (an there are four or so companies that load that bullet in their factory ammo). In base gel the expansion is near 100% reliable, while in a heavy clothing test you're looking at about 80% at 970 fps. Once you drop down around 870-900 fps, the heavy clothing expansion reliability falls to around 40% to 50% and you're effectively shooting FMJs half the time.
RIA Baby Rock and Kimber Micro:
RIA Baby Rock
I bought one because it was cheap, and I had low expectations. It surprised me in almost every respect. It is as accurate as any other .380 Pistol I own. The 3.75" barrel has no problems hitting the velocity sweet spot for the 90 gr XTP, and it proved to be exceptionally reliable. It's also very comfortable and low profile to carry IWB, although it's on the long side for pocket carry.
It also has a 7 round magazine, one more than the PPK/S in .380 ACP, and the same as a Kimber Micro if you're using the finger grip extension magazine in the Kimber rather than the flush 6 round magazine.
It is lightly longer than the PPK/S, but it also has a 1/4" advantage in barrel length, and it's thinner than the PPK/S.
The downside is that it's blow back operated and at the same weight as a PPK/S, it shares the same sharp recoil as the PPK/S.
Now...given potential issues with QA and consistency, I won't assume that all of them are as accurate and reliable as mine, but I will say that RIA got mine exactly right and I carry it with none of the reservations i have with my other .380 ACP pistols.
Ranger made Walther PPK/S and RIA Baby Rock:
Walther PPK/S
I've owned three of these over the years - two Interarms marked Ranger made examples, and a S&W made example. One of the Ranger made pistols is reliable enough to carry with Hornady 90 gr XTP (IMHO, at least 200 consecutive rounds with no failures). The other Ranger is near 100% reliable with FMJ but did not demonstrate my required standard of reliability with the Hornady 90 gr XTP although it does so with the 102 gr Golden Saber. The 102 gr GS is the .380 ACP hollow point I used to carry (it expands well but only penetrates about 9"-10").
The S&W was initially reliable with the 102 GS, but it started having fire control issues where it would drop the hammer prematurely, especially when doing a slow trigger pull. I also found the trigger would not engage the hammer at all in som orientations. A trip to the mother ship failed to fix the problem and I traded it off for one of the Rangers.
I also did not like the longer tang that S&W added. It's too long, and too sharp edged, causing it to dig in in IWB carry, becoming uncomfortable after a few hours and painful by the end of a long day.
One caveat to add here is that the PP series pistols are blow back operated, recoil is sharp with a .380 ACP self defense load, and the pistol needs to be held firmly and properly to give acceptable reliability. If someone is having a failure with FMJ quality rounds, I'm going to lay that on the shooter. Some shooters with large fleshy hands have issues with slide bite, but more often than not, with those large hand shooters, it's still an artifact of using a thumbs high grip that just isn't appropriate for the pistol.
I also own a pair of Manuhrin made Walther PPs in .32 ACP and they run like well oiled sewing machines with quality 71 gr FMJ, 60 gra silver tips or 60 gr XTPs. The silvertips expand very well but only give 8-10" of penetration while the 60 gr XTPs will mushroom nicely and give 12" at the same 1000-1050 fps velocity as their 90 gr , .380 ACP counterparts. The 3.9" barrel of the PP also gets them into that sweet spot.
The PP series pistols are far more pleasant to shoot in .32 ACP than they are in .380 ACP and you get an extra round in the magazine with the smaller round.
My point for discussing the PP in .32 ACP is that the PP series pistols were designed for .32 ACP and they seem to function more reliable with .32 ACP for most shooters, and I think a large part of that has to do with the lower recoil.
Ranger made PPK/S and S&W made PPK/S:
FEG AP9S and APK9S
These pistols are FEG clones of the PP and PPK/S, albeit with slightly heavier slides and grip frames as they were designed to accommodate 9x18 Makarov (in the AP9M and APK9M) as well as .380 ACP. They also make the AP7S and APK7S in .32 ACP/7.65 Browning.
They are steel frame pistols that are well made and very reliable. The chambers tend to be a bit more generous than their Walther counterparts and they'll feed a slightly over sized round that a Walther won't. On the flip side, they are also slightly less accurate, but are still more than accurate enough for self defense purposes.
Reliability is extremely good with FMJ with less picky preferences on the low cost end of the spectrum. Reliability with 90gr XTPs however is still mixed and pistol dependent. I have an AP9S that is reliable with it, and an APK9S that isn't.
The slightly larger grip frame and slightly heavier weight makes them slightly more pleasant to shoot than their Walther counterparts.
The fit and finish on the Interarms imported pistols is superb, while the fit and finish on the TGI imported pistols is only average.
FEG AP9S, APK9S and APK7S:
FEG AP9S, APK7S and Walther PP pistols:
FEG SMC
None of the positive comments I have for the AP series pistols apply to the SMC. It has the distinction of being the smallest semi-auto pistol imported since GCA 1968, and with an aluminum frame it's light weight as well as compact. It's just that mine isn't all that reliable with anything other than a few select loads of .380 FMJ.
S&W M&P Bodyguard
I bought of these because S&W had a special going on in the local shop and my cost out the door was $212. I bought it on Friday, shot it on Saturday and Sunday putting a few hundred rounds of several types of ammunition and I traded it off on Monday for a Star BM (even though I already had 2 of them).
I hated it that much.
It was not accurate and it was in no even remotely what I would define as reliable. The trigger pull was long, gritty and heavier than it needed to be with that length of pull. Hickock 45 did a review of one, and I lost a lot of respect for him when he stated he endorsed it after just doing a video with numerous failures to fire.
S&W may have made a few good ones, but mine was not one of them.
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I will comment on the concept of a "micro 9mm" pistol. Yes, you can get a Kimber Micro 9 or a similar sized Sig, however, I have yet to meet a person who shoots them really well or is willing to shoot them enough to get really good with them. They are too small to shoot really effectively, and IMHO, what you gain in terminal performance with the 9mm round, you lose in terms of poor bullet placement.
The smallest 9mm I carry is the CZ 2075 RAMI, as it's large enough to shoot really well, and yet still small enough to be very easy to conceal. The slight advantage in concealment with a Micro 9 (which is slightly longer than the Kimber Micro .380 here) isn't enough to offset the far better real work shooting performance of the CZ 2075 RAMI.