Chiming in from Utah... right down the road from Browning HQ. I am a lifelong Browning owner and collector. (Member of the Browning Collectors Association). I have Browning BBR, BAR, and A-bolts. I have killed more deer and elk with my Browning A-bolt II 30.06 with a Nikon Monarch scope than any other rifle I own. With that being said.... I bought a Browning A-bolt II Long Range Hunter in 300 WM. 26" barrel, 1:10 twist. I put a Leupold VX-6 HD scope on it. I fought that miserable bugger for 2 years and it would not group very well. I took it into Browning and had them look at it. It was suggested to glass bed it and install pillars. $400 later it still did not shoot any better. I hired a local gun company that builds custom long range rifles and does custom ammo loads that guaranteed they could make it shoot. 4 months later they returned my rifle and didn't charge me because they couldn't get it to shoot. Their opinion, as was mine, it would shoot ok but would never produce tight groups. I sold the A-bolt and immediately bought an X-bolt Long Range Hunter in 300 WM. 26" barrel 1:8 twist. Put another Leupold VX-6 scope on it. It didn't shoot any better than the A-bolt did! I load my own ammo. I can't tell you the loads I have spent on the bench. I have tried numerous powders, numerous brands and weights of bullets, different primers, and played with searing depth. I have bought new Norma brass and new Hornady brass. I have reloaded Winchester, Remington and Federal brass. Nothing makes a real difference. I finally threw my hands in the air and yelled UNCLE and sold the X-bolt. 3 years down the tube and uncountable hours. I have never fought with rifles and load development as much as those 2 rifles. As a side note... others in my family are as Browning loyal as I am. We bought 5 of the X-bolt long range rifles and 1 one Hell's Canyon. 4 of us have now given up and sold the rifles.
I also own a Remington Sendero in 300 WM. 26" barrel 1:10 twist. It is an absolute shooter. I can consistently shoot .30 groups with it. I have an old Leupold VX-III Long Range scope on it. Absolutely no trouble reloading accurate ammo for that rifle.
What I learned in the past three years with the Browning.... Browning rifles do not like heavy bullets! Best groups in both rifles came from lighter bullets. 168 GR. worked well.
Browning's shoot best with a tangent ojive bullet. It's just how they chamber the barrel. So the hornady eld x or the nosler bullets would more than likely be your best bet.
All the Browning's I've done load development for love the Hornady.
I have absolutely given up on Browning for long range rifles. I have shot several other factory long range rifles that will put shoot and outperform the Browning rifles.