No
The barrel on your rifle now has a bore diameter to fire .308" bullets. The 7mm-08 fires a 7mm bullet but it uses the parent .308 case necked down to 7mm to hold the bullet. Thus you get the designation of 7mm bullet in a .308 case, or the 7mm-08. They will in no way interchange other than you can use .308 cases and neck them down to fire the 7mm-08 bullets in the barrel you are ordering, so if you are into reloading and want to use any of the brass you have saved up, you could resize them to the 7mm-08 and save some money.