I will admit that I have been spoiled by high quality, long range oriented optics. They allow me to get away with some things that would have caused problems years ago. This week I was reminded of one of those problems.
Sig Optics was kind enough to send me a Sierra 3 rifle scope with their new BDX system. We just finished putting together “Project Stumpy” (more about that guy later) and I decided to mount the Sierra 3 on this rifle. I grabbed a Sig One-Piece 30mm mount from the box-o-goodies they sent and I mounted the scope on “Stumpy’s” scope base. The receiver for “Project Stumpy” is an Ultimatum Precision U300. The scope base that is included on the U300 has a 20 minute of angle incline to it. The one-piece Sig mount that I grabbed also has a 20 MOA incline to it. This resulted in a total of 40 MOA of incline for the system.
Forty minutes of angle is pretty significant, but it is something that I have knowingly done before. The Ultimatum Deadline project wears a 20 MOA Nightforce mount on its 20 MOA scope base. That rifle is topped with a Nightforce ATACR F1 with a ton of internal elevation travel. It makes it a simple task to obtain a 100 yard zero despite the angle in the mounting system. This gives me back that 40 MOA when I try to dial elevation for extreme ranges with that rifle.
The role of “Stumpy” and the design intent of the Sierra 3 is not for extreme long range shooting. The Sierra 3 sample that we have appears to have less than 40 MOA of total internal travel. The BDX system is designed to work as a ballistic holdover based on a 100 yard zero. This is not a limitation of the BDX. It is a malfunction in my brain-housing group that caused me to not check the incline of the mount I was using before installing it. It didn’t take any time at all to switch it over to the 0 MOA mount that I had sitting on the bench, but due to my mistake we lost a range day.
The purpose of this post is to again reinforce that there can be too much of a good thing. Canted bases with built in MOA are great for long range shooting. You can get away with a LOT of incline when dealing with scopes with tons on internal travel. If you can work with a 200 or 300 yard zero (many ELR Shooters do), then a ton of incline may not be a bad thing. With most shooters in most situations, if you cannot obtain a 100 yard zero, you need to re-evaluate how much incline is in your mounting system.
You can find more info on the Sig Sierra 3 6.5-20x BDX here: http://bit.ly/2zFmQGh