Front detent pin not going in all of the way

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  • Nickberg500

    Ultimate Member
    Sep 20, 2019
    1,064
    North of Baltimore County
    I can't tell if this is a problem with the LPK or the lower. When I put the front detent pin/spring in, it's not going in far enough to put the front takedown pin in. My last and final attempt sent one of my pins flying across the room. To be consistent, I tried the rear side as well, it appears to be too long there too

    The LPK is from KE Arms, "GI Parts Kit". The detent pins appear to be steel, unlike the brass looking ones from my other lower. Both of my lowers are from aero precision. I'm seeing what looks like rust on the inside of the buffer retainer (unless that's some sort of brown preservative).

    Should I cut the spring? Should I try to return the kit, minus the detent that went flying (as in, is this a terrible LPK that isn't worth my time)? Help?
     

    John from MD

    American Patriot
    MDS Supporter
    May 12, 2005
    22,734
    Socialist State of Maryland
    I don't know about the LPK but, if you have another lower, you can just pull the parts out and compare them as well as using a paperclip to see if the pin well for the detent has been drilled deep enough. All the detent pins I have seen are anodized steel, not brass.
     

    SkiPatrolDude

    Ultimate Member
    MDS Supporter
    Oct 24, 2017
    3,331
    Timonium-Lutherville
    I can't tell if this is a problem with the LPK or the lower. When I put the front detent pin/spring in, it's not going in far enough to put the front takedown pin in. My last and final attempt sent one of my pins flying across the room. To be consistent, I tried the rear side as well, it appears to be too long there too

    The LPK is from KE Arms, "GI Parts Kit". The detent pins appear to be steel, unlike the brass looking ones from my other lower. Both of my lowers are from aero precision.

    Should I cut the spring? Should I try to return the kit, minus the detent that went flying (as in, is this a terrible LPK that isn't worth my time)? Help?

    This tool is worth its weight in gold I tell you. Makes one of the worst parts about assembling a lower a breeze.

    https://www.amazon.com/Real-Avid-223-Pivot-Tool/dp/B078KSDGZ1

    Are you certain you didn't accidentally stack two detents back to back? I only say that because I absent mindedly did that once and it took me a few minutes of cursing to figure out what I did.

    What brand lower? What brand LPK? Are you sure you are using the correct spring?
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    If it turns out to be a tiny bit off, You can snip a bit off the spring(not the detent). Just make sure there is still enough tension to maintain the TD pin.
     

    Nickberg500

    Ultimate Member
    Sep 20, 2019
    1,064
    North of Baltimore County
    This tool is worth its weight in gold I tell you. Makes one of the worst parts about assembling a lower a breeze.

    https://www.amazon.com/Real-Avid-223-Pivot-Tool/dp/B078KSDGZ1

    Are you certain you didn't accidentally stack two detents back to back? I only say that because I absent mindedly did that once and it took me a few minutes of cursing to figure out what I did.

    What brand lower? What brand LPK? Are you sure you are using the correct spring?
    I'm positive I'm using the right parts, and the detent pin isn't double stacked. Ke arms LPK, aero precision lower.
     

    3paul10

    Ultimate Member
    MDS Supporter
    Mar 6, 2012
    4,879
    Western Maryland
    For what's it worth, I've had a few recently produced uppers not fit....holes wouldn't line up.....see if the upper will snap on another lower and see if that's an issue.
     

    Nickberg500

    Ultimate Member
    Sep 20, 2019
    1,064
    North of Baltimore County
    I don't know about the LPK but, if you have another lower, you can just pull the parts out and compare them as well as using a paperclip to see if the pin well for the detent has been drilled deep enough. All the detent pins I have seen are anodized steel, not brass.

    This tool is worth its weight in gold I tell you. Makes one of the worst parts about assembling a lower a breeze.

    https://www.amazon.com/Real-Avid-223-Pivot-Tool/dp/B078KSDGZ1

    Are you certain you didn't accidentally stack two detents back to back? I only say that because I absent mindedly did that once and it took me a few minutes of cursing to figure out what I did.

    What brand lower? What brand LPK? Are you sure you are using the correct spring?

    If it turns out to be a tiny bit off, You can snip a bit off the spring(not the detent). Just make sure there is still enough tension to maintain the TD pin.

    I think the problem is the springs are too narrow and the pin's tip doesn't sit in it. I pulled out the pin/spring on my main rifle and the spring there is wider, same length spring and pin though. I'll have to cut the bad springs and steal a pin from my working rifle
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    I think the problem is the springs are too narrow and the pin's tip doesn't sit in it. I pulled out the pin/spring on my main rifle and the spring there is wider, same length spring and pin though. I'll have to cut the bad springs and steal a pin from my working rifle
    You can't order new springs?


    These are Colt detent springs and they are in stock. This is a good seller and I buy all my lower parts "extras" from them as they restock them. They are very good at notifications...


    https://www.gandrtactical.com/Colt-Takedown-Pin-Spring_p_291.html
     

    Nickberg500

    Ultimate Member
    Sep 20, 2019
    1,064
    North of Baltimore County
    Ok this LPK is terrible. The magazine catch is TIGHT in the receiver. Like I'd have to file it to get it to fit smoothly. And my aero lower is mil-spec. I guess I should return it, idk if BBP will take it back though.
     

    Nickberg500

    Ultimate Member
    Sep 20, 2019
    1,064
    North of Baltimore County
    You can't order new springs?
    I'm shooting tomorrow and wanted to switch lowers, one with one pistol brace, one with the other that's incompatible with the first's buffer tube.

    Like I posted a second ago though, this LPK is terrible. The magazine catch is very very tight against the lower. I'll have to try returning it to BBP tomorrow.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    I'm shooting tomorrow and wanted to switch lowers, one with one pistol brace, one with the other that's incompatible with the first's buffer tube.

    Like I posted a second ago though, this LPK is terrible. The magazine catch is very very tight against the lower. I'll have to try returning it to BBP tomorrow.
    Did you see my update? Plan for the future. :)
     

    DutchV

    Ultimate Member
    Jul 8, 2012
    4,703
    Check the detent hole to make sure it doesn't have blast media stuck in it. You might have to poke around with a tiny drill bit to clean it out. That would keep the spring from seating all the way. I've seen that on an Aero lower.
     

    Scrounger

    Active Member
    Jul 16, 2018
    357
    Southern Maryland
    Check the detent hole to make sure it doesn't have blast media stuck in it. You might have to poke around with a tiny drill bit to clean it out. That would keep the spring from seating all the way. I've seen that on an Aero lower.

    I concur wholeheartedly what DutchV has posted. It could also be excess finish in the bottom of the hole, I have seen that more times than I can count.
     

    Nickberg500

    Ultimate Member
    Sep 20, 2019
    1,064
    North of Baltimore County
    Check the detent hole to make sure it doesn't have blast media stuck in it. You might have to poke around with a tiny drill bit to clean it out. That would keep the spring from seating all the way. I've seen that on an Aero lower.

    I concur wholeheartedly what DutchV has posted. It could also be excess finish in the bottom of the hole, I have seen that more times than I can count.

    Have you tried flushing the holes the springs go in? Sometimes crap gets in there and is not cleaned out during manufacture.

    I think the entire LPK is out of spec. Upon close inspection, comparing a working spring/pin, this spring/pin are the right length but the spring is too thin. I know it's not the lower because:

    A) the problem presents itself on both the front/back pin holes
    B) I tried fitting a known working pin/spring and it worked great without struggling. The bad one doesn't go in all the way no matter how hard I push.
    C) the magazine catch doesn't fit a mil-spec lower
    D) the buffer retainer is full of rust

    At this point I'm sure there will be even more issues if I continue trying to use this LPK.
     

    alucard0822

    For great Justice
    Oct 29, 2007
    17,643
    PA
    I've found a fair amount of out-of-spec stuff in LPKs recently, decent stuff too, almost always use CMMG, KAK or Aero. I almost always use an ambi/short throw selector, Magpul grip and aftermarket trigger, so I usually just buy a few pin and spring kits, then a bunch of individual parts those kits don't include, like buffer retainers. Ends up being pretty cheap for the "standard LPK parts I use, and easy to tell if something is out of spec.
     

    KIBarrister

    Opinionated Libertarian
    MDS Supporter
    Apr 10, 2013
    3,923
    Kent Island/Centreville
    It is for this reason, the cheapest LPK kit I will buy is CMMG. During the last shortage I was trying to put together a hunting rig for my son, and the only LPK I could find was some cheap Anderson tier garbage. Decent spring out of spec, mag release button wasn’t even threaded... just cheap Chinesium. The longer I live in this rock the more I am convinced buy once cry once is the Way.
     

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