3 hours east of LA (without traffic) is the middle of nowhere in the desert (mostly BLM and other public land, maybe Indian reservations) or the towns straddling the border between AZ and CA. There's really not much that far out that way. Right around 2 hours without traffic you're at the edge of the populated parts of Riverside County, like Palm Springs, Indio, etc. Once you pass that, there's almost nothing until you hit Blythe, just before the AZ border. There's also not a whole lot on the AZ side of the border, either.
Of course, there's lots of stuff short of 2 hours from LA that's not at all like LA, including my own area.
If you move to San Bernardino or Riverside Counties, you can get a CCW permit (LA County, forget it; Orange County is not a certainty, but it is a high probability). The closest you'd be in those counties to LA proper is probably 40 minutes without traffic, assuming you're not a slow driver. Traffic can make a 30 mile drive last over two hours, though, if you try to go to or from LA or other metro areas at the wrong time.
The handguns would legally-speaking need to be registered within a certain timeframe of establishing residency (I forget how long you have; never been something I needed to do myself). You can get away with not doing it, but if you get a CCW permit, no issuing agency in SoCal will add an unregistered handgun to a permit (needed to carry the handgun) and there are enhancements to certain crimes involving firearms (like unlawful carry) if the weapon is unregistered (illegal carry can be upgraded to a felony, for example). Also, pretty much no chance of getting an unregistered firearm back from LE if it ends up in their custody for any reason; then again, even registration is not enough. They want original receipts and crap like that for you to even have a chance at getting it back. Not sure if long guns also need to be registered now when you move here. That may have been required from 2014 onwards.
You can bring the ARs if you want if they are not on the Roberti-Roos and AR series ban lists exactly by both make and model and you make them CA-legal in terms of configuration. Fixed ten-round (or less) mag, meaning in this case that the mag cannot be removed without disassembly of the action, including pivoting the action open is an option for rifles, mandatory for pistols and AOWs. Featureless an option for rifles. Detachable mag, but has no flash suppressor, grenade or flare launcher, folding or collapsible stock, pistol grip, forward pistol or angled grip, or thumbhole stock. Can't legally bring in the hi-cap mags, but realistically you can get away with it under the present circumstances. You have the option of blocking them to ten rounds before bringing them in to make them legal. Ammo shouldn't be a problem.