Wednesday, March 18, 2020, will FINALLY purchase model #19115(after long consideration of #19121). Will use rifle for home defense and targeting (under 50 ft) at range. Do not understand all the "spec" terminology of optics for this carbine so cannot make an informed choice of sights.Need education on these terms and how to apply them to my indicated uses. Name brands and model number recommendations would be helpful. What reasonable range of "red dot" prices should I consider or expect? I understand that you only need to place the red dot(i.e. laser dot) on the target and engage without looking through the lens. I do understand "co-witness" and will not attempt it.(I have CT lasers on my pistols for use in home at night for intrusions.) Anyway, any assistance would be most appreciated.Many thanks in advance to those who respond.