Yeah, old topic. Hey let us beat it up again.
Now that i have a season on the grease holey gun, I'll report that I'm quite pleased with straight deer tallow. First I beeswaxed the hole (my current supply of beeswax is super hard-takes a lot of heat), then i filled it with tallow i rendered about three years ago. It's snow-white and quite firm.
I found the tallow handy for field re-loads and for weather-proofing the pan after priming on a wet or breezy day (or rust-proofing any ferrous metal at hand). The tallow picked up very little crud, and never "got on everything". It's easy enough to wipe off the crud and flick it on your hunting bro (tell him a bird flew over).
I expect to let the supply dwindle or even wipe it out for hot-weather shooting, then renew it this coming Fall. I may deepen the hole a speck too.
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Appears that, whilst i'm setting up a new workshop area, the puppy dog found my tallow hole. It's real doggone clean now!