Correct, three shot limit. And now on the honor system. No more plugs needed in shotguns, either.
When rifle was added, there was no easy way to "plug" a rifle, so the shotgun requirement was changed to match.
(It is also why I have an order in for a 5 round mag, just for hunting, since the 10 round standard mag is much larger than i could legally hunt deer with.)
Where do you get your 10 round mags, or do you modify 5.56 mags? All I find are the 5 round (BartZ & Bushmaster).