I used to use the old balance scale until I found out how inaccurate they were..Here is a shot read about going to better scales. https://theolddeerhunters.com/reloading-scale-safety/
I have been loading and shooting 280 for about 20 years. The best powders for accuracy and velocity are imr4831 and imr4350. My mountain rifle shoots 140 and 150 gn ballistic tips and 139 hornady's under an inch. Best is near max loads of imr4831 with cci mag primers with 150 gn ballistic tips...
I have been hand loading pistol ammo for many years but started reloading 9mm after it passed $6 a box during "his" first term. I load Berrys plated bullets mostly and have never had any problems with any of my 9mm's chambering. I shoot the same loads with a mixture of brass through my Glocks...
You need stonger load with faster burning powder..I shoot 5gns of unique and 115 or 125 gn and my 3 glocks and smith work fine with the load even if it is a medium load for a 115 gn.
I like 4064 for 20" but you may need a faster powder for shorter barrel. Here is link to my website that has data using Remington LTR http://clcweb.net/Shooting/Tactical_Shooting/Remington_M700_LTR/remington_m700_ltr.html
CC
I have found magnum primers work better with the real slow burning powders like Blue Dot or 4227. If you are using medium burning rate powders like unique, regular primers are fine.