The Lot Number is imprinted on the left tuck flap of the 500-round carton as indicated here.
The 1000-round intermediate carton does not have a Lot Number.

DO NOT USE WINCHESTER® M*22™ 22 Long Rifle RIMFIRE AMMUNITION WITH LOT NUMBERS GD42L or GD52L. Winchester has determined the above lots of 22 Long Rifle rimfire ammunition may contain double powder charges. Ammunition with double powder charges may subject the shooter or bystanders to a risk of serious personal injury and/or death, or cause firearm damage, rendering the firearm inoperable.

To determine if your ammunition is subject to this notice, review the Symbol Number and Lot Number. If it is Symbol Number S22LRT with a Lot Number GD42L or GD52L, immediately discontinue use. Contact Winchester toll-free at 866-423-5224 or visit Winchester’s Online Service Page to arrange free pick-up of the recalled ammunition.

This notice applies only to Symbol Number S22LRT with Lot Numbers GD42L and GD52L. Other Symbol Numbers or Lot Numbers are not subject to this recall. If you have any questions concerning this .22LR rimfire ammunition recall call Winchester toll-free 866-423-5224, or visit Winchester Customer Support online.

In general, we commend S&W for producing a rimfire clone of its M&P duty pistols. This allows M&P owners to cross-train with inexpensive .22LR ammo, without having to adapt to different ergonomics. Reportedly made by Walther, we suspect the new M&P22 will be reasonably accurate, but we’re skeptical of the quality of the trigger. Hopefully it will be better than the trigger on the full-size M&Ps.

Of course, if you want a superb trigger in a .22LR semi-auto pistol, there is the classic S&W model 41. For $1700.00 to $2000.00 you can find the fully engraved, 50th Anniversary Model 41 in presentation case on Gunbroker.com. First released in 2008, the engraved model 41 combines superior accuracy with stunning appearance.