The issue is not the standard CCI primers are too weak. They are about the same as a Win209 that work fine for me. The issue is they might be too weak for THAT breech plug. Western recommends mag primers because they got no idea what brand rifle you are shooting. The safe bet is to recommend the mag primers.
I meen i can light off BH209 in my Lehigh plugs using a WinT7 primer made for Triple7. They are very weak primers. I know guys that use the Rem STS in Omegas without a hiccup if they use a oring or shim the plug to fit them. BUT you sure wont get that primer to work well in the Encore Pro Hunter QRBP. I would be damn surprised if you did. Its a much longer plug with no deep concave face. The primer sits much further away from the powder.
One of the guys on the MML forum has used the NSI 209-686 primers for years in his CVAs. NSI also offer a 209-688 which is their version of a mag primer. They are Euro primers and fatter than most USA made 209s but they are as long as a Win209. They fit the CVA plugs better.
When i measured several samples of the NSI primers i got a better average of over .300 than any other brand including Win209s. They very very consistent in length. I like them so much im going to modify one of my Knight plugs so they fit. They are too fat to fit those plugs now.
Nobel 688 Lot# 4-69-16-2
.3025
.3025
.3025
.3015
.302
.300
.3025
.3005
.3025
.3025