Here is a side by side comparison of Remington 220gr 300 AAC Blackout and Corbon 220gr 300 Whisper. They both feed like a champ in my Model 1 16" upper. As you can see the 220 300 Blackout is shorter than the Corbon. It seems to feed faster like the Corbon 150gr(not pictured), as compared to the longer 220 300 Whisper. I'm thinking the 220 300 Whisper is more accurate in my rifle because the bullet is closer to the rifling.
300 BLK: 220gr. --- 300 Whisper 220gr.
Case length: 1.355 --------- 1.340
Neck dia. .332 --------- .332
OAL 2.090 --------- 2.214
All that reamer talk was someone making a buck, cause they are the same. And Model 1 said not to shoot it. But they are idiots there. Just covering their ass for a new product they no nothing about.
Why it took this long for someone to compare them I don't know. I just got my BLK's today.
Corbon 220gr. Whisper / Remington 220gr. AAC Blackout