For the Charles Daly AR-12S 10-round magazine, it is designed for the AR-12 platform, and those magazines generally support:
2¾″ (2 3/4") shells
3″ shells
That’s because AR-12 magazines are built around standard 12-gauge dimensions that accommodate both shell lengths.
Even though both sizes are technically compatible:
2¾″ shells → almost always feed reliably (this is what most users run)
3″ shells → may work, but can be tight or reduce capacity (often you won’t get a full 10 rounds loaded)
This is common with box magazines for AR-style shotguns—the longer shells take up more space and can affect feeding.

Hi Timothy and welcome. Yes, I have this model and the 10rd stick magazine holds both 3-inch and 2 34-inch shells. Cheers, stay safe and enjoy!

For the CD 10-round magazine, it’s an ar-12 platform that typically is supported by: 2¾″ and 3” shells.