When sighting in my new BCM mid-length I found that my new magpul rear sight had a different zero based on the aperture I was using. The large aperture hit 2.5-3 inches lower at 25 yrds. At first I thought something was wrong, but upon researching the topic I found that the 0-2 sight (big opening) will be zeroed at 200meters while the unmarked aperture will be zeroed at 300meters. My targets at 25 yards tend to line-up with this train of thought. However, I'm not sure this makes a lot of sense to me. For example, I plan on using my carbine for home defense and it makes sense to use the "large" aperture because of the increased visibility and more rapid target acquisition. However, at home defense ranges this will put me shooting a couple inches low, which is not good if any precision is required. It seems to me that this would be a problem in a military combat environment as well. I am relatively new to AR-15 open sights (all my previous AR-15 experience was with a scope), so it is more than possible that I am missing something. Please set me straight on my thought process and/or let me in on how you deal with this issue. Thank you very much! farmer Wanna kill these ads? We can help!