Marauder SAM stock.

If the info/specs below are correct the synthetic/plastic stock for the SAM only saves 2.4 ounces over the wood stock on the SAM.

SAM wood stock listed at 8 pounds.

SAM synthetic stock listed at 7.85 pounds.

If this is correct, the wood stock is 8 pounds and the synthetic is 7.85 pounds. .15 x 16oz = 2.4oz

P.S.

Sorry, just realized that the OP asked for info on "after market stock kits" for the SAM.

My bad... (Oops/smile)
 
As far as I know, there are no aftermarket stocks for the SAM/F&T models. The original beech stock does add some weight. The newer Turkish walnut stocks are lighter than the beech, but a little heavier than the syn. The beech stock forearm also felt "fat" to me. I fitted the original syn stock (gauge port in different location). I think the weight savings was around 10-12oz. Crosman does make a syn stock for it now, but I don't know the part number. You would have to call Customer Service and tell them you would like the syn stock for your SAM. Normally, they just want you to provide the part number. Tell them the part number is not on the schematic. The Turkish walnut is lighter than beech and better handling, too.
 
Something that can be done that would change the whole feel of the Marauder Semi-Auto is design a skeletonized bullpup style of stock. Even if the heavy steel air cylinder is left on there it would shoulder and handle like a dream. The action doesn't have to be all the way back on the shoulder to work well either. 

I've obviously been screwing around with the thing a bit without the stock on there and coming up with a plan... A new trigger needs to be mounted to the new stock and a linkage rod connection made to the original trigger. An extended one-piece cantilever scope mount will work on the front picatinny rail to move the scope forward.

Once a good cnc program is written then a stock can be easily machined. Anyone on this forum proficient at designing with the cad/cam type of software?