Thread: Same load increased velocity 🤔

Originally Posted by Hunty1

Just had a similar thing.
Thought I'd sorted a load for my 7/08 with RL17 and ELD-X 150gr. Tested up to 47.5gr in new lapua brass and settled on 47gr with a COAL of 2.93", No signs of pressure (book max = 47.5gr)

Fast forward a few months. Went to the range to measure some drops to get a handle om MV and bugger me getting sticky bolt lift and extractor marks. 455yrd drop suggested MV of 2900fps!!! Way too hot!

It's been bugging me as to the cause as I'm reasonably pedantic when I load. Only thing I can think of is I used Oneshot case lube and didn't clean the cases after sizing. I wonder if the brass is still slightly lubricated and hasn't got enough friction to grip the chamber walls and is generating high bolt thrust? Be keen to hear others thoughts?

All cases where trimmed to spec
Confident charge weights were okay as checked scales regular throughout with reff weights.
Projectiles are still over 1mm away from the lands.
temperature was about 12 degrees (within 5degrees of when original load development done).

If you did your load development on virgin brass I’d expect the velocity to increase on subsequent firings as less energy is lost to fireforming the case. I got 100fps gain on second firing of Lapua brass for a 6.5 284