.445 HB soup can

[looseprojectile]

I have just found in my junk, a hollow base mold.
It is a lee 445-288-M LEE. I suspect it was made for muzzel loaders.
I have a nice old 71 84 mauser, see where this is going?
The boolit has small lube grooves for tumble lube. IF I would load these in 11mm Mauser brass what powder should I start with? I have heard of hollow base boolits blowing the skirt when exiting the muzzel and giving poor results with too much pressure.
I am hoping some of you may have had some experience with something like this.
The 71 84 has a groove of .446.
Happy shooting

[Buckshot]

...............Since it appears the 'as cast' diameter pretty well matches the groove, and that .433" bore will displace a lot of lead too, I doubt you need to depend upon the skirt readily expanding. Therefore you may use a harder alloy. With the pressures you load the M71 and M71/84 to, by the time a WW type alloy HB slug reaches the end of that 30" bbl I don't think a blown skirt will be an issue.

In case you were needing load data, just use 45-70 Trapdoor data with comparable boolit weights, and reduce the charge 5% to start.

...........Buckshot