RE: Loads for 300 win mag
 

That's interesting and goes to show how different two rifles with the same chambering can be. I've got a .300 WM with a tight chambered 26" Lilja barrel. I hesitate going past 75 grs. of RL22 with a 165 gr. bullet. When I first started loading for it I used a published max of 78 grs with a 168 gr. TSX andwas getting velocities just shy of 3400 fps and hard bolt lift to go with it. So far I haven't tried RL22 with a 180 gr. bullet, but if I did I probably couldn't go past 72-73 grs. in my rifle.

I suppose I will purchase a couple of diverse marks in 190-210gn. I have a Chronograph, now recently need to find me an exceptional extent and opportunity to study.

75 Grains of RL22....
180 Grain Accubond
Winchester Brass (have done nickel coated, not much difference)
CCI Magnum Primers

Rifle- Tikka T-3
Scope- Zeiss Conquest 3.5-10x44

Sub MOA every group...10/10 at 6" gong @ 300 Yards...multiple bull elk, lots of deer...all agree, it is a great round :)

its your min spec custom chamber giving you the edge, of course the hand lapped lilja helps also.
RR

.300 Win. mag.
 

Load that has worked well for me in more than (1) factory .300 Win. Mag. rifle is 76.0 gr. RL22 Fed. 215 primer in a Winchester brass case (not nickel) using a Nosler 180 gr. Partition. RL22 can vary lot-to-lot and I would start at 72.0 gr. and work up. Some people I know have exceeded 76.0 gr. with certain lots of RL22 but you will only know by trial and error and using it in your particular rifle. My success was tight groups and over 3,000 fps in a 26" barreled Browning A-Bolt & a 24" barreled Remington 700. Both rifles shot under 1 MOA & the Remington was closer to 1/2 MOA consistently. I've also used the same load using Norma MRP when I could find it.