p5200,
The easiest way is to look into the mag well .
A center feed will feed the cartrdges to the center of the mag well before the bolt picks it up . When you open the bolt completely at the rear of the mag well there are two black lips that center the cartridge. A stagger feed will pick up the the cartridges as they lay, offset ( double stack ) and center the round as it is chambered.
Or you can remove the action from the stock , If the mag well comes with the reciever it is stagger feed . The center feed mag wells are not attached to the reciever.
Or you can measure the reciever bolt spacing . I don't remember what the difference is is spacing wise between the two but they are different . If you need me to I can check mine ...I have both..
Mike