I haven't used one in the field but I've handled many at the gun show. I've done some research as I needed a new scope a year ago. On the highest power setting for the 3-10X40 it only has 2.875" of eye relief. This isn't enough in my opinion unless it will be on something in the 257 Roberts class of lighter. If you are lying prone and tilt your head just a little forward for a clear sight picture you will be hit in the brow by the eyepiece of the scope. I went with a Nikon Monarch UCC 3-9X40 that I found on sale for $219.