I’d ask what? I’m pretty sure I read they use modern commercial barrels. I looked at this back in 1981 or so. I think I talked to them on the phone. And, I think I looked in their site in the last year or so and it doesn’t say that. If they had that, you KNOW that they’d be touting that. If you go to this page, it’s for their rifle kits:
The Hawken Shop-Hawken Rifles
Also, they don’t mention the first guy to do this, Art something. It says they bought it in 1990. They aren’t even in Missouri, it’s been moved to Washington state. Sure, it will say “Hawken” because they own the name. I’ve not held one. You’d have to ask an expert.