I have bedded only one commercial stock and that one was on a sporterized Krag.  The stock was a Bishop or Fajen from the 50s & the owner had just bolted the barreled action in & fired away until the stock cracked.  There was contact between the rear of the magazine & the stock at only one point & that is where the stock cracked.  Recoil had also started to spilt the stock behind the tang.  The cracks were minor and I was able to salvage the stock.  Since I could not add wood behind the magazine, I figured the best thing to do was glass bed the action.  I also slightly relieved the tang area and then drilled a .375" hole down through the bottom of the tang area into the pistol grip, about 1.5" deep (not visible when action is seated).  I filled that area with bedding compound as well to make sure the stock did not continue to split. 

So, I'd make sure the rear of magazine firmly contacts the wood & that the tang has a gap of about .04-.05" between the wood & metal.  The Krag has no recoil lug like the M1903 or Renington 700 and the rear of the magazine fills that function.

Do you have a GI stock to compare bedding with the commercial stock?