My first 7x300 WBY. was built in 1973 by the late Howard Wolfe of Mifflinburg Pa.
It became a very popular long range cartridge in Pa when Hornady introduced the 162 gr BTHP match bullet.
It also became the cartridge that caused the demise of the 6.5x300 WBY for long range hunting in Pa.
There were actually no good powder choices available that would maximize the cartridge potential at that time. H 570 was pretty good but also hard to come by.
H870 was also pretty good and easily available at that time.
But when 7828 came along it really improved the performance of the 7x300 WBY.
Today i have 2 7x300s, one has a 30” barrel, and the other has a 27” barrel.
Velocity is the same in both guns with the same load.
My current load is 78 gr 7828 with the 162 gr bullet using a 215 primer.
I strongly recommend using caution when working up a load with 7828.
We still use the 162 gr bullet for hunting because it shoots flatter than the heavier ones out to about 1200 yards. And when you get to 1200 yards, its time for a better gun anyway.
I would recommend starting at 75 gr with the 162 gr bullet.
Load just one, then one each with 1/2 gr increases till you see pressure signs like a sticky bolt.
First sign of pressure, STOP, back up a half grain and use seating depth to find accuracy before changing the load.
Shoot everything over a chronagraph, a target isnt necessary initially, a dirt pile is all you need.
Your looking for velocity first, tuning the load can come later.
When you find the velocity, then load 3 and shoot them for a group.
As stated, play with seating depth before changing the powder charge.
