I am looking in purchases some butler creek scope covers for my guns and i can't figure out what size covers I need the scopes are 3-9x40 NikoN prostaffs so if any of you know what size you would need would be great
Depends on model scope. Go to butler creek and see what size your obj and eye pieces are. Here is a link to the sizes of the flip open caps. You need to measure your scopes. http://www.butler-creek.com/productsImages/charts/flip_scope_chart.html
Please note that the chart provided by Butler Creek is a guideline. To ensure a proper fit of Butler Creek Scope Covers, you must measure your riflescope with a micrometer or a caliper, and then choose the size that offers the closest fit.
I just ran across a chart that recommends a #11 for the eyepiece and a #29 for the objective. When I bought mine, the store also sold Nikon Scopes, so I had the clerk try them on. I had previously bought the wrong size and I didn't want to make another trip. My front one is a little snug, but goes on and off OK. The chart also recommended the Blizzard models to be #04 and #07.