Take a look at the attached group of photos,and see if this might be the cause. In pic 1,you see how far the pin comes down to hold the stock in place at it's full extension (without the stock folded out). In pic 2, you see the difference when the stock is unfolded out and locked in place (see the difference). You will also note that in pic 3,how the place on the stock where the stock is locked in the outward position is slanted slightly. You can also see in pic 4,a different view of the same region.
My suggestion would be to check yours,paying close attention to the areas highlighted in my pics,on your stock. If yours also does'nt let the pin come down fully,you can file or dremel out a little where the pin hits on the stock,to give it room to fully extend.Be VERY careful,and remove a little at a time,checking it constantly! It is ALWAYS easier to remove a little more than to ADD metal!!!!
I checked the fit on several of my factory folders,and they varied (how far the pin would come down with the stock extended)on each of them. Good Luck!
