So, the retainer pin in my bolt carrier group scares me. When I first got the rifle, my gun dealer showed me how to disassemble and oil the group, and had trouble getting the pin back in, so he hammered it, so now it has a hammered-looking top. I still have to hammer it some to get it in, so if anything it’s getting flatter.
Since I started shooting my rifle, the pin looks corroded to me. It feels brittle to me, but it is so far staying in one piece, that does take all the hammering I have to do to get it into position.
My question is: Is this normal? Does it need to be replaced? If it does, where would I look, and what should I look for?
If it really bothers you replace it. You could even get a stainless steel one from the hardware store. If you order it from a gun parts shop I would go ahead and get the BCG field repair kit for the extra parts to have. You want to have some resistance so that it stays where you put it but you shouldn’t need a hammer.
If you spread it open so that it will stay still its harder to get in. If you file a “ramp” on the short side of the cotter pin it makes it much easier to get in and it will still stay put. You always want to bend the short side leave the long side straight for this application.
Have you tried squeezing it instead of hammering it? They usually do have a bit of ‘spread’ to them and my experience has always been to squeeze the open end together and then insert.
You can also try turning it some as you try to insert it. I have grabbed it on the fat end with needle nose pliers to gently turn it. I have one BCG that is a bit fussy with the pin. It usually works for me.
I think it is KNS Tactical that makes solid shaft pins both in steel and stainless steel. Another option to consider.
Once you have the ‘long side’ started you can roll your thumb/finger into the short side in order to push it in against the long side while you push down with a finger from your other hand. I have NEVER had to beat one in with a hammer, but I have tapped them lightly with a screwdriver handle or something similar that is softer than the pin.
I am very new to the AR platform, but this is what works for the sample of one that I have. Turn the BCG over such that the little cotter pin is above the firing pin. That tiny bit of gravity seems to guide it right into the hole on the opposite side. If I try to put it in with the firing pin above the cotter pin it’s always a wrestle to get it lined up. That has been my experience so far.
Sorry I’m Australian we called them Longnose pliers you would call them needle nose. Slide the Needle nose pliers in to BCG next to the firing pin and get the cotter pen Sliding it into place
I’m going to go with @Craig6 , go get another one! If you get another pin and it’s still to tight file it down a bit.
I have cleaned many dozens of AR-15, M-16 and M-4s and I do not remember having to pound one in, tap but not pound. For what it’s worth.
Guys/Girls!! This is a cotter pin. It is supposed to stay where you put it which is why it a PITA to get in. Long nose or needle nose pliers are handy when you bend a leg over like on a ball joint for a car. The AR cotter pin is just to keep the firing pin where it belongs. It doesn’t have to be bent to non function. A little hump in the middle is the best fix I’ve seen. Clamp some vice grips on the very ends and stick a screwdriver in the middle and twist it to form a hump. The ends stay togther and the hump holds it still. It’s really not that hard.
