lightest subsonic to cycle an AR?

[silvery37]

I am building a 300 whisper AR with a noveske barrel. I am planning on using 220 grain matchkings most of the time. I would also like to have a more economical subsonic load to use in the rifle. What is the lightest bullet I can shoot subsonic and still cycle the action? I can test this myself but would save some money if I had an idea of where to start.

[steezo757]

I've have a Noveske 10.5" 300 Fireball barrel. I've gotten Remington Core-Lokt 180gr to cycle with 2015. The grouping however, was not too great.

[AlcoholicusMaximus]

Hi Steezo,I am thinking about getting that same barrel. Is It ok to ask how much they cost?