I'm under the impression that Serengeti
made the original bottom metal, that both McMillan and Manners use for the bottom metal inlets on their stocks for the Sako M995 action.
The bottom metal was a one time product, and as such, is becoming quite rare and hard to come by.
Mr. Tom Manners
took on a M995 T3 stock build for me. Recommend you contact Manners as well as McMillan to see what your options are for restocking your M995. Both either had the bottom metal, or had access to it, and needed to add 150 bucks to your stock build because of it.
By the way, Mr. Richard Near
makes a nice base for that action, and Jard
makes a trigger for it.
I believe your max mag working COAL for a repeater will be around 3.750 with the M995 magazines.
Good luck with your build.