HBN and velocity loss

[1shot]

I just got a new Bartlien 1-8” twist, canted land bbl. chambered up in 6.5x284. It’s throated specifically for the 140 JLK bullets. I decided that I would start with HBN coated bullets from the first round and evaluate as I went along. I loaded up five different time tested, proven loads with four rounds per recipe. The only difference was the powder, and the charge weight. I fired one round and cleaned for the first five rounds using one each of the five different loads. All rounds fired were clocked through the chrono and recorded. After the five break-in rounds, I proceeded to fire 3 shot groups to see how the accuracy was. Nearly across the board, the five different loads were 125-175 fps SLOWER than what other shooters are getting with the same powder charges, using the same bullets, brass and bbl. length. My question is approximately how much of a powder charge increase is needed to bring the velocity up to speed? Additionally, by increasing the powder, does the added heat, offset the reduction of bullet friction with-in the bore.
Thank you all in advance for any information you have,
Lloyd

 

[CPorter]

I have found I need about .2 grains more powder to make up the velocity difference when using WS2 or BN. I can't give you a definitive answer on the heat but I have noticed on my last three barrels that the heat checking came later in the the round count, by several hundred rounds, than the barrels I shot naked bullets. Powders, primers, case and bullets have changed several times so I can't positively attribute the changes to the bullet lube.