If you're sold on the Howa mini action, you can buy the version with the heavy barrel (which isn't all that heavy). It has a 5/8x24 thread. And I have that 7.62x39 HB version with an area 419 2 port muzzle brake. The howa is a high quality action, accurate, and with a good trigger (no funky blade). The cons with the howa: (1) The 90 degree bolt lift is problematic for mounting a scope with a large eyepiece bell. (2) The plastic floorplate/trigger guard is flimsy and can crack around the hole where the stock/action bolts go through. Plus, the magazine latch is not all that positive and is configured so that it is easy to accidentally dump a magazine. The solution is to replace the floorplate/trigger guard with a Diversified Innovative Products (DIP), machined aluminum floorplate and re-designed magazine latch. Unfortunately, that's about 150 $, but worth it in my opinion. This may sound like I'm down on the howa, but I'm not. I have added a mini howa, chambered for 6.5 grendel, in an MDT oryx chassis and love it. Both my howas, are not going anywhere.
I had a ruger american chambered for .300 blackout (not the ranch version). I did not like it. The 60 degree bolt lift is nice for scope clearance, but the steeper cocking ramp means more bolt lift effort. Also, the Ruger American has a shorter bolt handle, which just intensifies the effort. So that meant installing a longer handle and knob. I also don't like the plastic bolt shroud and bladed trigger, and so I replaced those. But that is just a personal preference. The plastic magazine with my ruger was flimsy. One literally fell apart into pieces with the second use. That rifle is gone (my son really wanted it). I would not buy another Ruger American.
"Taylorforce's" idea of the CZ600 is interesting. I haven't handled or shot a CZ, but if I were in the market for a .223 or 7.62x39, I would take a look at one. It's worth investigating.
