The good folks at Magpul Industries released their PMag 20 Limiters for shipping. They are replacement lock plates for the 20 round PMags so you can limit the round capacity to either 5 or 10 rounds to meet certain hunting restrictions. Since it is a simple drop in replacement for the standard lock place, this isn't a permanent modification. As soon as hunting season is over, swap them back out and your round count is back at 20.
Suggested retail price is $13.95. Sold in packs of 3. Pictures courtesy of Magpul Industries.