Ok so my 308 is in the B&C Varmint or A-5 type stock and I just picked up a Rock Sopmod for it. What adapter do I need to order in order to be able to mount it.
You can probably use this to convert the swivel stud that usually comes with your type of rail system to a picatinny rail so it can work, here is the link: Swivel to picatinny
But personally think this would look ugly and end up too tall. I would suggest using the seekins rail and just mount it over the freeland rail system you have and mount it securely with proper hardware as far forward as you can and still have the remainder of the rail left to mount other things. Hope this helps.
You need the Accu-Shot BT28 AFAR Kit ($34.95)
Accuracy International – Freeland – Anschutz – Rail Kit
This photo is from the Accu-Shot website, and is what I use on my B&C stock. I even used it on my AICS (bottom stock in photo) while I was waiting on the Badger IMUNS parts.