Originally Posted by
chaded
W209 primers will ignite bh209 at close to zero degrees from my experience.
No disagreement but........ if you want 100% reliable ignition 100% of the time, the magnum primers should be used in most cases in extreme cold. There's a reason Western recommends magnum primers. BH is actually a smokeless propellant and must have the bullet compressed on the propellant hard for consistent ignition and groups. Magnum primers use higher pressure than standard primers, thus ignition is more consistent.