M21 is a good idea, but the M14 base gun was problematic -- it's not inherently overly accurate, and while you can make an M14 very accurate, it doesn't tend to stay that way under hard use. Keeping the M21s in the inventory shooting at sniping level accuracy was problematic and the main shortcoming of that system.
The SR-25/Mk 11/M110 is a better way to get the same job done.
|