Takedown pin detent and problematic lowers

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  • RuralRifleGuy

    Active Member
    Aug 16, 2018
    918
    Queenstown
    Is there any reason a takedown pin detent couldn’t be the full length of the hole so it doesn’t require a spring? I have two ACC blemished lowers that seem to have milling issues at the takedown pin detent area.

    I tried KNS locking takedown pins and they don’t seat close enough to the lower to fully engage the ball detents on the left side. They were also ugly. I J-B Welded the takedown detent area and redrilled the holes but the issue came right back. I think the original milling by the manufacturer made the pocket too wide.

    I took some brass rod and got it down to the right size to fit in the takedown pin detent holes and now I’m wondering if I should leave them the full length and not use the springs. The backplate would keep them in place and I know they work with the pins. Any reason this wouldn’t be ok?

    Attached is a photo of the original issue.
     

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    smokey

    2A TEACHER
    Jan 31, 2008
    31,412
    The pocket looks like it's cut off center towards the mag release side. I suppose you could drill the end of the pin, tap it, and put an oversized head screw in it or something to secure it to bypass having a detent in it at all. With how cheap lowers are, I'd probably ditch that and grab another one cut to spec. If going with a longer detent, you should still cut down a small spring to allow some movement for the detent to engage with the pin's recesses.
     

    DeadCenter

    Member
    May 12, 2018
    23
    With a full length 'detent rod', you would have to remove/loosen the back plate every time you wanted to separate the upper from the lower.

    Look closely at the slot in the take down pin.. there are deeper holes on the ends, where normally, the detent would be pushed into by the spring, so that the take down pin does not fall out of the lower. That is the reason for the spring as well as the beveled edge on the detent, to be able to ramp itself out of that hole.

    Is the problem that a normal detent falls out of the blemished area?
    Maybe a half length 'detent rod' with a beveled edge and a half length spring?

    Or, get a new lower and use this one to keep napkins from flying away on windy picnic days ;)

    For me, a blemish is cosmetic on an otherwise functional component.
    If this was sold as a blem, I would argue that it is non-functional.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,815

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    RuralRifleGuy

    Active Member
    Aug 16, 2018
    918
    Queenstown
    Turns out the lowers are just garbage. Made new pin detents that are twice the size of standard ones and still used a spring, installed them and everything works fine. Proper retention of the pin, no issues at all.

    Went to try an upper on it and the takedown pin holes are drilled too low. No gap between receivers, so short of drilling out the upper so the holes line up (not happening) there’s nothing I’m willing to do and I’m not wasting more time on them. The upper is cerakoted but it’s more than just a thick application of finish preventing it from working.

    Tried to support a local small business and it bit me in the ass. Back to Aero for all receivers, it will cost more but I’ve yet to have any issue when assembling a build using them.
     

    smokey

    2A TEACHER
    Jan 31, 2008
    31,412
    Yup, When you see an entire FCG pocket machined offcenter (it doesn't look like the detent hole is wrong, it looks like it's the whole pocket...check wall thickness on each side), you know the rest of it is probably FUBAR as well. I'd out the manufacturer for this on here to keep everyone else from having to go through this...or to at least put the manufacturer on notice that they need to get their sh!t together. This is unacceptable. Having a booboo with the coating, or scratches is a blem. Having a lower that's radically out of spec is not a blem.
     

    RuralRifleGuy

    Active Member
    Aug 16, 2018
    918
    Queenstown
    Yup, When you see an entire FCG pocket machined offcenter (it doesn't look like the detent hole is wrong, it looks like it's the whole pocket...check wall thickness on each side), you know the rest of it is probably FUBAR as well. I'd out the manufacturer for this on here to keep everyone else from having to go through this...or to at least put the manufacturer on notice that they need to get their sh!t together. This is unacceptable. Having a booboo with the coating, or scratches is a blem. Having a lower that's radically out of spec is not a blem.

    I'm not sure it’s worth outing them as the blem lowers were only available at my LGS and not statewide. My LGS sells their complete rifles and pistols which have zero of these issues and he built a rifle using a blem, but it was a later SN. I don’t want to tarnish a small businesses name over something that’s fixed now in their manufacturing. I will be contacting them to see if they were aware when they sent them to my LGS of these issues.

    Measuring the two lowers against an Aero lower using calipers neither of them match the Aero specs and they don’t match between the two either even though they are sequential.
     

    3paul10

    Ultimate Member
    MDS Supporter
    Mar 6, 2012
    4,879
    Western Maryland
    Ok, clearly the proper way isnt going to work....for the hell of it, could you use an oversize bolt, or machine something similar, to use as takedown "pin"? I hate to throw away any lower...
     

    RuralRifleGuy

    Active Member
    Aug 16, 2018
    918
    Queenstown
    Ok, clearly the proper way isnt going to work....for the hell of it, could you use an oversize bolt, or machine something similar, to use as takedown "pin"? I hate to throw away any lower...

    I can probably make something to make it work, but for now they are stored away and clearly marked to not use. This way I don’t install everything and then remember why they weren’t used. I don’t like to throw away any lowers either which is why I’ve been trying to make it work. With a 77r for each I’d rather not destroy them but it also sucks having a constant reminder around.

    What I will most likely do is try uppers as I buy them and see if I can find one that fits better. I don’t know if the manufacturer makes uppers or uses a specific one, I’ll ask him when I email him about the issues. It might be that my Aero uppers don’t work with them but something else does. Situation still sucks but there could at least be a solution.
     

    RuralRifleGuy

    Active Member
    Aug 16, 2018
    918
    Queenstown
    Heard back from the manufacturer, he provided some information on what can be done to remedy the issue and offered to have me come in and he would take care of mating the receivers. I ended up performing the actions he suggested and now the takedown pins are going in fine. I didn’t have extra uppers hanging around for these so it wouldn't have made sense for him to mate them to an upper.

    I probably wouldn’t buy another blem lower from them but I don’t expect them to have any more now that they are producing them for their own firearms and some other manufacturers. Good helpful customer service and I’d buy production lowers from them based on the willingness to help. Going to order sets of KNS locking pins for them so I don’t have to deal with the detents. Now I just need to build them out, test them, and then figure out finishing them since they are raw.
     

    smokey

    2A TEACHER
    Jan 31, 2008
    31,412
    Heard back from the manufacturer, he provided some information on what can be done to remedy the issue and offered to have me come in and he would take care of mating the receivers. I ended up performing the actions he suggested and now the takedown pins are going in fine. I didn’t have extra uppers hanging around for these so it wouldn't have made sense for him to mate them to an upper.

    I probably wouldn’t buy another blem lower from them but I don’t expect them to have any more now that they are producing them for their own firearms and some other manufacturers. Good helpful customer service and I’d buy production lowers from them based on the willingness to help. Going to order sets of KNS locking pins for them so I don’t have to deal with the detents. Now I just need to build them out, test them, and then figure out finishing them since they are raw.

    I dunno, that lower is FUBAR. Good customer service to me would look like... come on in and we'll give you a new lower that's in spec.
     

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