Has anyone found issues with high pressures at start load when using privvy partizan cases (.243 win). Has anyone found / measured the internal capacity of privvy cases and found them to be slightly smaller than other makes?
For a full explanation please read details below. Sorry if its a bit much but still a relative novice to reloading and trying to understand more.
Had started to get split necks on my Hornady cases. I moved on to my Privvy Partizan cases, as are my largest batch of cases that are already re-sized and trimmed to length (2.0350"). I have been loading 58gr Vmax for .243 win with 47.5 gr H380 with COL of 2.600 which is the minimum recommend COL.This load was worked up from start load and had no issues only stopped at 47.5gr as grouping was good. Now book lists start load of 46 gr to max 49gr with above combination. As I changed cases I started with lower amount than I had been using, 46.5 gr. Found bolt stiffer than normal to lift once fired. Have tried 46 gr and still have same effect but not quiet as stiff. When I re-chamber these fired cases the bolt is stiff to close, however if I re-chamber any other fired case all is as should be. I have measured the privvy cases just above the head and get a measurement of between .4705 - .4720 all other makes of case are max .4705 or less ( should be .470 ) hence the stiffness of the bolt I guess.
I had been advised that changing only 1 component in a tested load should not cause any real issues, other than grouping may be effected.
Has anyone had similar issue.
I have some other makes of fired cases with primers in and have worked out the case capacity by filling with water. Average of H2o capcity seems to be
Hornady cases Ave 55.4 (have been full length re-sized and trimmed several times.)
Privvy cases Ave 54.7 (cases in question 2nd firing)
Fiocchi cases Ave 54.6 (1st fire
Federal cases Ave 54.6 (1st fire)
So the hornady cases seem to have a greater capacity than all the others I have checked. Hence I suppose should have higher pressures in other cases for identical load and COL. Suggestions please on best way to proceed on developing load. Should I increase the COL to reduce the pressure and start at minimum load ? Some of the other cases I have did not require trimming after FL sizing so I guess there internal capacity could be less, so should I always increase the COL slightly than that list as min COL?