Nosler. I've seen too much variation in quality in the MRC rifles. The Noslers that I have looked at were nicely finished and I think have a higher level of QC.
I have a Nosler M48 and a bergara. Both great guns but the bergara outshoots the nosler easily and is way less expensive. Both customer services are outstanding as well.
From what I've seen, the Nosler M48 is a quality rifle that shoots their factory ammo very nicely. I can't speak to the Montana X3, no experience with them.
Something to note... If you are not a fan of recoil the M48 is going to kick a little more than the X3 with that really nice, integrated directional muzzle brake. You'd have some gunsmithing to do to get a brake on the Nosler as the barrel is not threaded. Guys have done it on those rigs though and love them.
33 Nolser in M48 would buy one again in a heart beat..... Never shot a Montana Rifle Co gun so cant compare but love my M48 its turned into my go to gun.
Nosler M48. Though I can’t say anything about the MRC, I do like my M48 Liberty a lot. Definitely not light but a very nice rifle to shoot. Mine’s a 7mm Rem. So you would be a little lighter.
I have a Montana X2 in 6.5-284 took me a year to get it after ordering.i have had the rifle for 2 years now. When it arrived before I even shot it wasn’t feeding right so I sent it back on my dime. I got it back they said the magazine was bent and in their crooked. I’m still getting feeding issues and seems to me like I have a little creep in the trigger so I’m going to take it to a local gunsmith and have him work on it don’t feel like spending another $40-50 to send it back and it not being fixed again. Other than that it shoots good and I like the rifle just experienced some bad luck I think.