Which AR magazine works best for Whisper??

[tpfdchn]

This question has probably been asked and answered more than once, but since I don't frequent the boards often, here goes: All my AR magazines have internal ribs that guide the .22 cal bullets into the feed ramps. The larger .30 cal bullets jam on these and won't feed reliably.

There's got to be a better solution than skiving these ribs off from P-mags with a wood chisel.

Help out a newbie here and let me know what the best solution is for this. There's got to be AR mags out there that are suitable for .300 Whisper.

Thanx,