Re: 220 matchking loads for 300 weatherby
The 220 will shoot much better further out if that's your objective.
I have several 300 Weatherby's for 1000 yd match shooting and also for LR hunting. Some are my wifes guns and some are mine.
The secret as you know is to get away from the Weatherby "Free Bore" and have a custom barrel chambered correctly and get rid of the free bore.
Some of our 300 Weatherbys are in the 16 1/2 lb class and others are in the Heavy Benchrest class.
My loads in the 30" barrels (some are .950" at the muzzle and others are 1.450" at the muzzle) are 77 Gr of RL 22 with the 220 Gr Sierra and a Federal 210 Match primer. You don't need a mag primer in it.
With the 240 Gr bullets, I cut the load to 72 grs of the same powder.
Another good load for the 200gr or the 220 is 75.5 grs of H 4831.
I have used 80 grs of RL 25 with the 200 gr Sierra with good results also.
The accuracy range for the 220 gr seems to be right around 3000 to 3040 FPS for my friends 300 Webs and mine also.
A 29" barrel should only make a difference of 25 to 35 FPS in velocity.
The above loads worked fine in my guns and of course I take NO responsibility as to what it does in any other rifle.