Mossberg 500 Red Dot HELP

[Delta762]

I have a new Mossberg 500 that's tapped so I can install a scope onto it. I just purchased the Top Rail system:

http://cgi.ebay.com/NEW-UTG-WEAVER-BASE-RAIL-MOUNT-FOR-MOSSBERG-500-590-835_W0QQitemZ310106563002QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item310106563002&_trksid=p3286.c0.m14&_trkparms=72:1205|66:2|65:12|39:1|240:1318|301:1|293:1|294:50#ht_2548wt_910

Now, I have purchased this Red Dot:

http://cgi.ebay.com/Optronics-Red-Dot-Series-Riflescopes-1x30-mm_W0QQitemZ350066958384QQcategoryZ1291QQcmdZViewItem

But the scope wont fit onto the weaver rail system on the top of my Gun. Did I buy the wrong type of scope? This says Shotgun use. The Scope fits, but the part to clamp it down on will not fit. The screw is to short, and the other piece that tightens it cant reach the base of the scope. I hope someone out there can answer my question, other wise I will just sell the scope and buy the right one. I got this scope for a damn good deal I hope there was no mistake made while doing this purchase.

Thanks.

[zippy13]

Greetings, Delta762, and welcome aboard,

Your scope is intended for a narrower rail than your Weaver -- like the a rails common to .22s and air gun mounts. Since the angles are similar, you can use a file and narrowize the rail you have. I've done it to Weaver and Aimpoint mounts to accommodate red dots on handguns. Also, you may have to use a round file to clearance the cross screw notch. If you're careful, the scope hardware will cover the bright spots you've created on the rail.
Good luck