I sent an email to Criterion barrels about a week ago. Here's the response:
Paul,
Paul,
We have already produced barrels in 6mm ARC and are currently evaluating the cartridge. This requires evaluating several different lengths, twists, and a wide range of ammunition. After we toast a few barrels we will make an evaluation on the viability of a full production run. I greatly appreciate your interest in our products, please let me know if you have any other questions.
Sincerely,
Michael Ross
W172N13050 Division Rd. | Germantown, WI 53022
Phone: (262) 628-8749 | www.criterionbarrels.com