The single item that was the most beneficial to the employment of the A4 as a DMR was the Trijicon TA-01 NSN.
Bipods were usually Harris on either a KAC or ARMS adaptor. Those were frequently removed though.
On the USMC side in the early GWOT timeframe, there were two parallel programs, the “West Coast SAM-R”, and the “East Coast SAM-R”.
The West Coast SAM-R was the most cost efficient with no training program association. The East Coast SAM-R and Mk 12 programs had a higher overall performance potential, but required higher education to meet the potential.