85lc

The reason I insist on Magnum primers is from my own experience

Several years ago I tried out a 4198 BPE equivalent load in my Williams and Powell .577 Snider DR

With no prior knowledge I used standard primers

The bullets only just got out of the barrel and went 20 yards downrange leaving much unburnt powder everywhere around the action (I reported the problems on this forum at the time)

The problem is that under these circumstances there is a possibility of complete ignition (i.e an explosion with extreme pressure issues)

Magnum primers solved the problem

Others have reported similar issues

I cannot remember whether I used a filler but I do now

I can only assume the charge was not ignited correctly

The problem seems to have gone away for me as I now longer use BPE instead of BP, having a BP licence here in the UK

Good luck in your shooting whichever way you choose

TH 44