For general home defense, I prefer a shotgun, but a .38 will do too. An AR-15, especially in tight quarters, is way too much overkill, cost (both the weapon and the ammo), and if anyone does break-in to your home while you are not there, that becomes the thing they will steal.
A pistol in .40 is very snappy and hard for many people to shoot accurately. Remember, a larger pistol with a smaller round is going to have much less recoil and have higher capacity. For a home defense pistol, I'd recommend a high capacity 9mm. The very dependable standard for many law enforcement offices is the Glock 17(17 rounds in the magazine). I have the Glock 19 (15 rounds in the magazine). They are popular with law enfrocement because they are very dependable and easy to operate. Many manufacturers make a pistol with a manual safety, if that's what you want. Use hollow point ammo if legal to minimize penetration through walls, etc... Most ranges will rent guns to try out, as long as you buy ammo in the store to feed them. I tend to buy made in America products, but with personal safety I make an exception for the reliability and ease of operation a Glock provides. ARs are good for home defense, but more cumbersome than many want to deal with. An AR in .40 would be easy to handle because an AR will weigh 2-3 times what a handgun weighs and that reduces recoil. You may have trouble finding places to practice shooting with an AR and ammo is more expensive. You can shoot a pistol caliber handgun at any indoor range. If you go with a revolver, I recommend a 3 to 4 inch .357 magnum. You can fire .38 from a .357 magnum and have much less recoil. A .357 will be more solidly built than a .38.
You can always buy a few stripped AR lowers and store them as an "investment". They could become quite valuable if a Democrat becomes president and declares war on gun ownership.
I think the AR is too much over kill. If I had a house I would buy the AR Maybe a revolver but only 38 rounds. I cant shoot the bigger caliber. I did shoot the 38 ok and the recoil was fine.
I don't recommend a firearm then. Any firearm you buy is going to penetrate those walls and possibly kill people on the other side. The AR15, with the right ammo, will penetrate less than any handgun or shotgun though.....unless you use a shotgun with birdshot.
You own each bullet that leaves that barrel. If you miss and kill someone on the other side of that wall, you'll be charged with murder.
i may rent out a house in August. Maybe I should wait. I dont want to put myself in a position when I accidently shoot my neighbor and I am screwed in Court and legal system for years.
Even worse is carrying the burden you accidentally killed someone for the rest of your life. It's not easy even when you meant to do it, and it was done in combat. If you live in an appartment, harden your entrances with something like this so that your door can't be kicked in: Your first line of defense in the home is making sure the ****ers can't get in.
And thus, proof your "get a dog an and an alarm" recommendation wasn't worth the electrons it was written in, eh? Perhaps you should have gotten more information so you could maker a realistic assessment rather than reflexively acting on ignorance.
An AR15 carbine or pistol, in a major pistol caliber is a better choice for home defense than a shotgun in almost every situation - while you give up single-round stopping power, you get a lighter, smaller, easier to handle and more versatile weapon with a larger magazine, less recoil and faster follow-up shots.
Sorry you are not being truthful, an inside siren is limited to 106 Db, and most cannot achieve that sound pressure level (SPL) at all. The only one that I know of, which I commonly specify, is the Honeywell Wave 2. https://www.security.honeywellhome.com/product-repository/wave2-1-sounding-devices I can actually produce 106 Db, now that sound pressure is measured inside the home at10 feet from the source, measure it outside the home with the windows open and it will be way lower because of the Inverse Square Law, which states as the distance from the source doubles, the SPL is reduced to a fourth of what was produced at the source. As such outside the home, an inside sirens SPL could be so low it would be literally masked by ambient sounds such as traffic etc. however if the windows are closed it might not even be heard at all, which is why we normally install an outside siren in a protected tamper resistant cabinet, and they can produce a SPL of 120Db, for residential I spec the W Box Technologies 0E-OUTDSIREN, it has a SPL of 120Db and only pulls 560 Ma of current and at $35 is reasonably priced, if my subscriber wants a siren and strobe I will use the Potter Electric Signal, SSX52 which also produces 120Db, has a selections of color strobe light's, and pulls just under 1000 Ma of current and like the W box is fairly priced at $48. https://www.wboxtech.com/north-america/product/205/indooroutdoor-self-contained-120db-siren/ https://www.pottersignal.com/product/114/ssx-52-series By the way I was licensed in 1981 as a Broward County Certified Alarm Contractor, and in 1989 I 81CLVC151X, I upgraded my license to Florida statewide in 1989 EF0000499 and have installed or have supervised the installation of thousands of both residential and U.L. listed commercial alarm systems, as such I understand their limitations and know when someone is BS'ing (which you did) as to what they can or cannot do.
Inside walls yes, with wood framed outside walls maybe, with CBS construction, probably not going to go outside the home.