Installing Seekins Ambidextrous Safety

Installing Seekins Ambidextrous Safety
Same Process for AR10 as AR15

Be careful not to lose spring and detent when pulling the handle off of the lower

Now the detent rides this grove on the selector. There are two options full throw and long throw based on what you choose you will need to orient the selector shaft in the hole a particular way. If you choose short throw you will need to orient the shorter groove to line up with the detent hole on the receiver and if you choose the regular throw you will need to line up the longer groove with the detent hole. I chose a short throw. 

If you have to tap it in, the part is just too tight. 

Here I compare the Military Spec part to the Seekins and yep if comparing in metric you can tell pretty easy that there are some differences. Now to fix this you never ever modify the receiver holes, you modify the part. Below I will go through that with you. This variance could be the part itself or the coating on the part. I will throw a disclaimer this is a home milled 80% lower, so it could have been my problem but I will say the Milspec safety had absolutely no issues.

Cut the paper down to width and roll around the shaft. This will be a custom fit part after your done.

A little 1000 grit dry wet sandpaper will do the trick. Add a little oil to the part so it doesn't get too hot while turning the part. With 1000 grit the part will have a nice smooth finish.

During the sanding part, you may want to periodically check fitment.

Notice handle detent sprint hole. Feed the spring into it and carefully reassemble.

Short Throw Function

When you finally decide the choice of short lever vs long lever and short throw 60-degree vs full 90-degree throw use blue Loctite on the selector lever screws to prevent back out over time.