178 GR ELD-X OAL 2.800 VS 168 GR HPBTMK OAL 2.800

[color_me_gone]

Okay, I took note today with having to maintain the OAL of both of these cases in order to fit into the magazines there is going to be a greater distance of the ojive curve from the lands and groves between these two loads and the 178 may result in a compressed load using IMR-4064 due to it having a greater length and the 168. How is the greater distance from the lands and groves going to affect pressure and velocity

 

[Doom]

You are looking at different weight bullets with totally different shapes, from different suppliers designed for totally different purposes. There is little to compare from one to the other. It probably a safe bet that at maximum loads the velocity of the 178 will be 50-100 fps slower.

Compressed loads with 4064 are not unusual in 308, if that's your caliber.