Well, the sling rings are permanent and there is no way to mount a bi-pod on the M40A1. It is odd, but remember the A1 was designed about 30 years ago, there were no harris bi-pods around, etc. My understanding is that the thought process was to teach competitive shooting positions with the sling, etc. Its great, but it can't beat a good bi-pod if there is not other rest around!
MEL
MEL