Avoid this piece of equipment.  I purchased this adapter to put the Specter Gear MOUT sling, and was disappointed when i installed it and found that i could not collapse my stock to the first position.  GG&G doesn't mention this fact on their website, you only find out once you get the instruction sheet out.  Better to get a buttstock wrench and install their regular rear sling adapter for collapsing stocks.

When you say you can't collapse it to the first position, do you mean you can't close the stock till it's flush with the receiver or that it won't close to the first stop out from fully closed?