I'm not sure which of the supplied adapters I've used, maybe the Mossberg but its a seamless fit

A new M10x1mm Allen cap bolt and a bit of work with the dremmel/grinder/file and the job was done.
The allen bolt is quite heavily modded to fit in the recess of the stock/adapter but it works a treat.
OAL to end of buffer tube 44"
OAL to end of stock 46"
LOP at shortest 13"