I just recently purchased a KAC SR15E3 Mod 1 carbine, which is my first AR. My experience & knowledge with AR’s is definitely lacking compared to the folks here at m4carbine.net, so I figured I would ask here about a potential issue with the rifle.
First off, I would just like to say the rifle so far has exceeded my expectations. The fit and finish is incredible, the rifle is definitely quality. It is light and points extremely well, and is a really soft shooter. I have put a t1 micro w/larue qd mount, magpul ctr stock, miad grip and vickers vcas sling on the rifle.
The only potential issue I have so far with the rifle is with the rear receiver pin. The pin seems to walk out on its own, if that makes since. I can literally shake the pin out of the rifle, which doesn’t seem right for a battle ready rifle.
The only thing that I could think of, is that while installing the magpul MIAD grip I might have screwed something up. There appears to be a spring/pin in the lower that holds the receiver pin in place, maybe after installing the new grip this part got messed up. I’m not sure if this is making any sense, I’m having a hard time explaining it. I can take pictures if this will make it any more clear.
Anyways, if someone has any suggestions please let me know. I assume this is not normal, but maybe it is?
Just a guess, but when you replaced the stock did you make sure the spring and detent were in place? The only reason I say that is that recently a friend replaced his stock and didn’t notice that the spring and detent fell out.
On closer examination, I must be missing the spring and brass detent that should be holding this pin in. I must’ve lost these items when replacing the grip.
*edit - just posted this as you did skonie. Looks like I need to find a replacement for those parts.
The spring and detent pin held in by the pisto grip is for the saftey/selector not the rear pin detent.
The rear pin detent is held in by the stock plate( forgive the incorrect nomenclature) as the other poster stated.
If you didnt change your stock remove the stock and buffer tube assembly and see if the pin and spring are installed correctly. You can just loosen the castle nut enough to get the plate to back out and the spring pop up(without removing or turning the buffer tube). You have a quality rifle and its possible an oopps occured during assembly or reassembly.
The rear receiver pin detent and spring are held in by the end plate at the rear of the lower, not the grip. Did you are someone else remove the stock?
On my rifle, there appears to be two holes under the grip for spring and detent assemblies. One, for the selector switch, which is currently in place. The second hole appears to go right to the rear takedown pin. Looking at the pin itself, there is a slot cut out for what would appear to be a detent to hold it into place. Am I wrong about this?
There doesn’t seem to be any mechanism from the rear stock plate to keep this pin in place. Maybe we are talking about different pins? Also, I changed the stock to a CTR, but I did not remove the buffer assembly.
I believe the KAC rifle is different in that the pistol grip retains both the selector lever spring and detent as well as the rear take down spring and detent.
I performed the work in my living room. Living in an apartment, I don’t really have a proper work area. I’m looking for the brass detent right now, but I imagine it’s gone.
I ordered a couple of brass detents and springs from brownells, if anything it will be good to have a couple of backups.
Ok, see from what I’ve gathered so far, the MIAD grip that I have put on the rifle is the culprit. It looks like the spring and detent used on the sr15 is not compatible with the MIAD, and modifications are required in order to use this grip and keep the takedown pin from backing out.
Anybody have any experience with a MIAD grip and SR15 rifle? What are my options here? It looks like a regular detent and spring won’t help, though I won’t really know until I try.
I will give KAC a call on monday, hopefully I can get this sorted out before then though.
You will need to mark the spot to drill a hole and then drill a hole in the grip. You need to make sure not to drill the hole to deep. I am fairly certain although not 100% that the spring and detent are standard size.
What? The detent and spring for the SR15 Rifles with the qd cups in the receiver have the oddly placed detent hole as noted. You do NOT need to drill any holes in the grip. The problem with the MIAD is there already a hole there, and the SR15 requires a flat spot, like on an A2 to hold the pin and spring in place.
The pin and spring are standard.
One option you have with these rifles it to tap the detent hole 4/40 machine thread and install an 1/8" set screw. Then, you’ll need to trim roughly one coil off the detent spring to account for the length of the set screw. If you’re interested in doing this, thus alleviating any further grip swap headaches, do a search here for a post by KevinB of KAC on the subject, or PM me. I’m no SME, but I’ve done this to a couple of KAC lowers and it is the preferred method of using a MIAD.
You don’t need to drill any holes. While the detent and spring is supported by the grip instead of the receiver end plate, there is no need for more holes.
Installing the detent and spring is no different than on a standard AR15, except instead of the end plate, the grip is what holds it in.
Just make sure when you slide the grip on you don’t put a bend in the spring.
I had a couple of different grips on my SR15 and never felt the need to tap for a machine screw. If you know the parts are there and their function, its easy enough.
This is the easiest solution. The MIAD’s modular design makes it a little trickier to use on the SR15 lower. If you’re committed to using the MIAD, installing a set screw to hold the detent and spring in place is the next best option.
When the spare detent and spring show up, I will tap the hole and install the set screw. That seems to be the best solution, and doesn’t require me to worry about that spring and detent anymore.
When using this method, I only need to tap the first 1/8" of the hole, enough to set the set screw in the receiver so its flush with the bottom, right? I’ve never taped anything, but it doesn’t look too hard.
