Fireforming k-hornet

[hornet]

Thank you for your answers.
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I'm not too sure why your loads "have" to fit the magazine.

I use my hornet hunting arctic grouse in the winter. Hand-feed a rifle using thick gloves is not very practical. Fumble around without gloves and trigger pull can be badly affected. Birds don't always like to hang around and wait for me to reload.
I typically bring 250rds on a 5-day trip and some brass is always lost in the snow. Fireforming needs to be done on a fairly frequent basis and that's why I'm looking for the best way to do this.Preferebly hunting at the same time.

I've also been using cheap 55gr FMJ and in my gun they stabilize if vel. excced 1,900ft/s. Would they tumble and create a mess if used on game?
They buck wind a lot better than blunt 45gr hornet-bullets, and were I hunt it's always windy.