ML Primers - 209 vs 209M

[Varmint Hunter]

I am using BlackHorn 209 powder in my T/C 209x50 ML. Currently experimenting with loads at all levels.

I gave away my 777 209 primers and was given some CCI 209M primers which are apparently "magnum" shotshell primers. I also picked up some CCI 209 (non-magnum) primers which I haven't used yet.

Any opinions as to the relative performance of these two primers for use in my application?
Any reason to use one over the other?
Anyone tried both yet?

As a note: Even when using the magnum primer I was getting velocities BELOW what I expected. 250gr sabots were running at about 2,000 ft/sec with 120gr V charge of BH. I was expecting velocities closer to 2,200 ft/sec. I believe the WEIGHED charge of BH was 82.4gr.

[Busta]

I had some hang/delayed/mis-fires with the standard CCI 209's in my Disc Extreme with the Non-Full Plastic Jacket 209 conversion. CCI 209M gave good ignition, but both of these CCI's primers would slide back in the battery cup. Never had a problem with the Winchester W209's as far as ignition, but IMO the Federal 209A is the toughest and hottest available 209 primer.