We have come a long way from milling down an original carrying handle to the current models of back up iron sights or BUIS.
Still you need to have an understanding of what you expect out of your BUIS. In the perfect world you won’t need them, but if you do you will want a few characteristics to get that first round lethal strike.
The first decision is fixed versus folding. When we didn’t have much faith in our red dot sights or RDS. If you’re using suboptimal red dot sights then fixed backups are kind of mandatory. Eventually you will want to embrace the folding styles. So why folding over fixed? Simple, field of view. Being able to get an unobstructed view of the battle space should be priority number one. Sometimes it’s not about how cool you look or much multi-cam you have on, if the bad guy sees you first and dumps a magazine in your direction that’s not good. Un-cluttering your life is a good thing, so is uncluttering your field of view.
From there you need to think about what style of front sight to go with for peak performance. I’m not going to lie, I favor the rounded hood of the HK style front sights over the tradition wings of the M4’s. I don’t know if it’s all the years of looking through them or how my eye tends to center square things in round holes, but they are hard to beat. Once you’ve figured out the front sight, you need to consider the rear sights.
By default the larger aperture should be deployed as the primary. Whether low light or combat engagements, you want the larger aperture for sure. You also want both sights to lock in the up position. Spring loaded are nice, but can produce false sight alignments. If there is a positive lock in the deployed condition it will out weigh the speed of deployment. You can get by with down optic techniques at close range, but for extended usage locking in place is the way to go.
The other consideration is once you pick a manufacture you’re going to want to stick with them for both front and rear. Mixing sight manufactures is bad business. Most don’t play well with others so you tend to run out of corrections.
Lastly, take time to mount them correctly. Start by mounting them in the correct position and direction. I’ve seen them mounted backwards and at weird locations. While you can zero them at any distance most sights are designed with a certain distance for the corrective value. If you don’t know the corrective value then that’s problem one. Once you know the distance for optimal usage things are pretty simple. I’ve seen some crazy stuff and I tend to default to standard corrective values, with some locations it’s trial and error… I hate trial and error. Just so we’re clear the distance they are mounted is relative to the corrective value.
Lastly, take the time to apply thread locker when installing along with a witness mark. Make it a practice to inspect the witness mark periodically and those bad boys will be right as rain.
Back up iron sights, still mandatory, just not invasive anymore.