Newb Questions

[Stan_TheGunNut]

I have taken the plunge and decided to get a 300 Whisper. My Whisper is based on the AR platform. I was about to order some bullets and wanted to make sure that a load using the 240 grain Sierra Match Kings HPBT would be able to fit inside the AR magazine and reliably feed. The heavy bullets that I have found do not have a cannelure....is this a problem?

I'd also appreciate any advice that any of you could provide. Thanks