A BUG should be easily concealable without too much fuss. That means it should be very small. This usually means a semi auto pistol since small frame revolvers like the Ruger LCR are small, but they aren't particularly thin due to that pesky cylinder. When it comes to concealment, it is hard to beat thin. So, in the semi-auto field there are a few choices, among them are the KelTec, Ruger LCP, Bodyguard, etc. All have their supporters and it doesn't really matter which one you choose if it suits you - fits your hand well and you don't hate the design - and it is reliable with sufficient power to stop a threat at the last resort.
Some carry .22 cal BUGs on the theory that they can hit what they aim at and a bunch of .22s slamming into you will certainly act as a deterrent. Maybe.I support the view that, with modern self defense ammunition like the Hornady Critical Defense and Speer Gold Dot rounds, the .380 semi auto is a sufficiently powerful self defense weapon, whether carried as a BUG or a main weapon. For my personal use, I have the Ruger LCP.
Now, the question is, where and how to carry the thing when you also have a bigger handgun strapped somewhere about your body? Common sense offers a few guidelines.Unless you enjoy many heavy items hanging off your belt, inside the waistband or out, you will probably want to carry your BUG somewhere other than there. If your main gun is worn on your strong side, especially at 3, 4 or 5 o'clock, you don't want your BUG sitting snugly in your strong side back pocket. Chances are the main gun holster will interfere with drawing the BUG. However, if you use a Remora holster for your main carry, this would not be as big an issue, since once you have drawin your main gun, the Remora will collapse under the belt's pressure and shouldn't act as a barrier to the BUG in the same side back pocket.
You could carry the BUG in a cross-draw rig on your weak side, which seems an attractive proposition until you conisder that if someone directly in front of you goes for your gun in a fight, if they get it out of it's holster on your cross-draw side, it is immediately pointing directly at you. Not something I would want to happen. So, for me, as much as I like the idea, cross-draw rigs are out, for BUG or main carry.
You could carry the BUG IWB (In Waist Band) or OWB (Outside Waist Band) on your weak side at 3, 4, or 5 o'clock, which would make sense if your strong side arm or hand were injured or otherwise occupied, like holding someone off you. You would need to practice a lot to become proficient with your "weak" side hand, which is not a bad idea anyway. However, until I decide to do that and become sufficiently proficient at it, the BUG weak side position is out.
I don't consider SOB (Small Of the Back) a viable carry anyway since I wouldn't want to fall on my gun and drive it into my spine. I would think that sitting would be a literal pain in the back too.There is always ankle carry, but I can't see myself doing that. Besides, I normally wear cowboy boots, so I'd think access would be a real issue for me.
So, my conclusion is that the best place for a BUG is in a pocket. Front or back, depending on how the main weapon is carried. For this, the BUG should be slim, no fat or sticky grips and fitted to a holster that will keep it upright and oriented correctly, cover the trigger for safety and be adaptable for use in any pocket on any side for the most flexibility. For this, the synthetic pocket holsters will work well and there are many to choose from at reasonable cost. Some include a panel that sits between the gun and the outside of the pocket to keep the gun from printing (showing it's outline through your pocket).
I prefer leather holsters fitted to the particular gun, so my choices right now would be leather pocket holsters that have detachable leather panels for anti-printing, and that can be reconfigured to either the front or back pockets. The two I know about now, and I am sure there are others, are made by craftsmen in Texas. One is from Doug Childers of Bear Creek Holsters in New Braunfelds and the other by D. M. Bullard in Azle, Tesas. Both are excellent holsters and will surely outlast me.
I will eventually end up with a pocket holster from one of these makers after I sell a few of the now useless ones I have to fund yet another holster. The good thing is I am about at the end of my search for solid carry methods and holsters so that should be the last of them I will need to buy, at least for the guns I have now.
I also believe there is great value in finding what works best for your everyday carry weapon, or weapons, then sticking to that so that you become always familiar with them and won't get flustered if you need to react in a hurry and you are running on full automatic. It won't do to start asking yourself, now where did I put that BUG, or main carry weapon today, when seconds count.
Photo: D.M. Bullard PWC (Pocket Wallet Carry) holster.