What is the difference between the DTA SRS and the DTA SRS Covert. The DTA SRS is now offered in: .243 Win, .308 Win, .300 Win, .338LM, .260 Rem, 7mm, 6.5 x 47 mm. Is the Covert compatible with the above calibers? or is just restricted to the .308? I know the DTA SRS 308 barrel is a little...