Thread: Practice make perfect 300prc load development

The big day has come and passed and my semi custom Bergara 300PRC arrived this week after a very patient 3 week wait
I'll run through the set up then I'll get into the load development
24" Bergara Wilderness barrel and action
Timney Elite trigger
Precision Platforms picatinny rail
Precision Platforms carbon stock
DPT MK2 suppressor with braked cap
Wheeler 2 piece cant bubble rings
Athlon Midas BTR gen 2 4.5-27x50 scope
Total package weighs 4.3kg including the DPT

This rifle came with a partially developed load with Hornady brass, 225gn eldm's over adi 2217 seated at 20thou off the lands.
The loads were substantially longer than SAAMI but still easily mag fed...happy days.
Took said hand loads to the range today to get acquainted with the rifle and also validate the speed as the previous owner had only used drop at 500y to calculate the velocity.
The claimed velocity was 2840fps the magnetospeed confirmed velocity was a anemic 2700fps.....
So whilst it was super accurate shooting a .6" 6 shot group, I find myself just wanting a little bit more as the cartridge is capable of pushing them to 2850fps at book max.
I'll be happy if I can get 2750-2800fps with the same accuracy.
I knew I'd be tweaking the load as I'm switching to virgin Lapua brass, keeping the powder and projectiles the same.

Now the Hornady brass hand loads were loaded with 77gn of 2217 (remember that the C.O.A.L is substantially longer than SAAMI so will require more powder to reach the book quoted velocity) as stated above these hand loads achieved 2700fps.
The load seated at 20thou off the lands seems accurate so I'll stick with that seating depth for now.
I have loaded a charge ladder to see where I need to be for the velocity I want, and check for pressure.
Unsure how the Lapua brass will compare as far as velocity goes I have loaded my charge ladder as below:

77gn (same as Hornady hand loads that came with the rifle)
78gn
78.5gn
79gn
79.5gn
80gn

The book data shows a fairly linear increase over the entire data set for this powder and projectile choice of approximately 3gn for 100fps increase in velocity hence my charge ladder is over 3 gn, I'm expecting the Lapua may have less internal volume as it's heavier so I may actually see an increase even with the same load, I won't get a chance to shoot the ladder till next weekend now but it's loaded ready to go.