When you decide to buy a firearm, you must consider several factors.
First, I'd suggest you buy a used or good condition LE trade in revolver in .357magnum or .38spl +P. A DA only sidearm in stainless steel with a 3" or 4" barrel. Most US police agencies now use semi auto pistols but there are still a few police revolvers out there(S&W model 10, 65, 66; Ruger GP or Speed Six).
If you want a new or NIB(new in box) revolver buy a Ruger GP100 4" or the DA only SP101(5 shot .357magnum). The 3" S&W 686 .357magnum plus or 7 round is good too. Ruger is marketing a great Talo 4" .357magnum revolver for approx $650.00 USD. That would be a great buy for your use(s).
If you really want a mid size semi auto, start with a DA only model like a Beretta PX4 C model, a P224 or P229R DAK or a S&W SD in .40/9x19mm.
I wouldn't buy a Glock XDm Kahr or a single action(SA) until you are ready.
I'd also learn & understand the local gun/use of force laws. Join the NRA and/or a local gun club to practice with.
for good cleaning products & gun care items.
Most weapons can be cleaned with CLPs like LPX Gunzilla Ballistol or Weaponshield. Do not use a lot of oil/CLP. A small bottle can last a long time.
When you buy or carry your weapons, don't be brash or make threats. Keep a low profile & learn to control your emotions. As stated often too, do not drink alcohol or take medications if you are carrying a loaded weapon.
Be fully ready to explain or justify your acts if you are in a lethal force event. Many DAs, criminal investigators or lawyers(civil) would love to rip you to shreds.
stay safe & enjoy the shooting sports;
www.nra.org www.gunvideo.com www.gunzilla.us www.mpro7.com www.jgsales.com www.sgammo.com www.shopcorbon.com www.midwayusa.com www.policehq.com www.gunsamerica.com
PS: Btw; only use FACTORY made ammunition for protection or carry. No handloads or reloads. Law enforcement officers or court officials could make that a issue too. Avoid the legal hassles & just use proven, well made rounds.