Here's a comparison of Luger S/42 and Lahti M40 stock lugs...You can see the latch cut is in a different place...
If you do a GoogleSearch for 'Lahti Stock' you'll see a bewildering array of angles of stock to grip frame...It's a WAG on my part, but I think some of those stocks are Luger stocks modified for the Lahti that aren't quite right as far as angle is concerned...
Leather holsters, at Sarco & Numrich, seem to be quite reasonable...
