How do I know

If I have a center feed or stagger feed. Based on year model flat back accu trigger?

I think there's more involved but, if the mag is attatched to the bottom of the action when it's removed from the stock (blind mag) , it's a stagger feed.
If the mag stays in the bottom of the stock when the action is removed, it's a center feed.
With the Accu Trigger, my guess is it would be a center feed.
Someone correct me if I'am wrong. ;)

There are staggered feed accutrigger models. All flatback actions are staggered feed non- accutrigger.

I have a 11 in .243 accu trigger mag stays in the stock so stagger feed?

Staggerfeed mags. stay attached to the action. Centerfeed mags. stay in the stock.

As the man said:

Just take the barreled action out of the stock (two screws). If the magazine box it attached to the action, it's a SF. If it is attached to the stock, it's a center feed.

uj

Do a little research......go to the home page and look at the article section under "Magazines and conversions".