OLDer J frame Revolver, is my first suggestion.
Proven in this very role being a BUG.
RIG Grease takes care of perspiration concerns. I would go with a blued one - Model 36 for instance. Qualified gunsmith to make DAO only, bob the hammer .
All carbon steel, will assist with less felt recoil. Access needs to be with either hand/abilty to shoot weak handed.
Model 37, Alloy and carbon steel is another, being lighter carries easier, will be more felt recoil. Not that bad, training is key. Beats these new alloys all the way around...
I would NOT use a newer alloy,( Ti, Si) ammo restrictions, the stupid locks, and if hurt and having to use one...recoil is going to really hurt and perhaps not allow effective follow up shots. Carbon steel is best, alloy and CS as in Model 37 next best.
If matters get serious, and being a BUG the situation indeed will be, the RELIABLE operation of a firearm with either hand, in any position -upside down, downed man , on side..."port up - port down" , having been shot, cut, stabbed and weak from injuries...no time to do a Tap Rack Bang because of Limpwristing - or any other malf. Malfs like confined spaces and steering wheels or, doors not allowing slide to operate as should.
.38spl being a low pressure rd , if fired in a confined space is less likely to ruin her hearing.
Not a place for stupid political locks on a gun, not a time for bean counter inferior metallurgy to fail...A proven reliable OLDer J frame BUG to stop an immediate threat - NOW!
In undercover work, one does not need a shiny gun. One does not always need to draw questions about a "new design costing a lot of money". One does not often need to give off impressions of being firearm savvy. A used Police trade in Model 36 ( or similar blue gun) can be unobtrusive, and if asked, " I stole it" , " I found it at a Pawn shop", "It was in the car we stole", "in the house we broke into"...who cares? Make up something to tell the BGs associating with - something.
One UC buddy of mine- chided about his antique wheel gun "he stole", Was given a Glock 19 to use by his new "associates", he carried it. He carried the 36 as well. Sure the 19 was stolen, still he had a role to play and did so. These 'associates" were bad folks and he was accepted into their world. He was given a M16 / too..."need a backseat gun dude...here". I didn't type AR 15 for reason...
Also, for BUG BUG...NAA .22 Mag Mini- Revolver, maybe even two...depends on her UC role.
I am not a LEO, never been one. In a former life I learned from LEO, UCs, and others. I was "prime" to be a target for kidnapping. So my last ditch "gotta do something" even if I was overwhelmed and outnumbered, being marched to the store at gunpoint..and later to back of shop and have my head used for a target after they got what they came for - or - put in the trunk of vehicle for later fun...
'I gotta piss', I kept one where I could access thru my fly. I had another either in pocket or under my shirt where being patted down would not be felt ( hopefully). I had two handcuff keys on person and small razors on person accessible from hands in front, or back, to cut rope. My knives were figured to be taken with the primary guns...if things got that bad.
Just what some Mentors and Elders shared. Some seasoned LEOs and some seasoned Military folks like Rangers and Spl Forces passed onto me.
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If...IF...since this lady LEO is used to a Glock, the Glock 26 would my suggestion as she is used to using it, same MOA.
She needs as much relialble confidence with Proven firearms as she can have.
And Training with these, in various conditions, types of dress and in vehicles.
IMO/ IME
Regards,
Steve