300 whisper vs 300/221

[Garrett]

Originally Posted by Hoser

If you are using an older SSK Industries barrel, you might need to use 221 brass.

How old is "old"? I've got an SSK barrel that I bought 7 or 8 years ago. The only 5.56 brass that it won't chamber also won't chamber in my Noveske .300FB barrel. (and I forget what headstamp it was. Something foreign, anyway.)

But any U.S. 5.56/.223 brass has always been just fine in either chamber.