ChaseFan9 Posted May 14, 2015 Report Share Posted May 14, 2015 (edited) Okay, since my SSA-E finally came in I decided it was time to assemble my lower. I'm using a Matrix Aerospace lower and a parts kit that came with it (essentially, Chris modified the bolt catch for me). I went to install the rear takedown pin, detent, spring, and my Luth MBA-2, and I realized the rear spring was much too short as it disappeared into the rear of the lower. I checked all my parts before assembly, and the front and rear detent springs are exactly the same. I've looked around and I can't find anything but the standard spring length. It almost seems like I need a 716 rear detent spring, but I think those are like $60. Sorry, it's late and I'm tired and frustrated Edit:My rear takedown pin detent and spring are held in place with the stock, not the grip. Not sure If I was very clear about that... Edited May 14, 2015 by ChaseFan9 Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 14, 2015 Report Share Posted May 14, 2015 cut a piece of wire hanger to add length. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 14, 2015 Report Share Posted May 14, 2015 Does your Lower Receiver have threads in the hole for the spring . Some Manufacturers use a set screw or plug to tension that spring . If its not threaded , you can thread it , some here do that even with the AR 15 platform . I have compression spring stock & can cut you a spring to what ever length you want , also . Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted May 14, 2015 Author Report Share Posted May 14, 2015 Does your Lower Receiver have threads in the hole for the spring . Some Manufacturers use a set screw or plug to tension that spring . If its not threaded , you can thread it , some here do that even with the AR 15 platform . I have compression spring stock & can cut you a spring to what ever length you want , also . I was thinking the same thing, but I checked the hole and no threads, and my LPK didn't come with the plug screw. I read about people threading the hole, but I can't seem to find a small enough tap. I'd rather keep from modifying the receiver if I can help it. I'm probably gonna try Robo's coat hanger mod, but if that doesn't work, how much would you charge me for a spring, SS? It's standard detent spring diameter, but it looks like it needs to be closer to 1.750" long Quote Link to comment Share on other sites More sharing options...
AngelDeVille Posted May 14, 2015 Report Share Posted May 14, 2015 4-40 tap, and a 3/8" 4-40 set screw will solve the problem. Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted May 14, 2015 Author Report Share Posted May 14, 2015 4-40 tap, and a 3/8" 4-40 set screw will solve the problem. Sorry, I meant I can't find a 4-40 here at the house. I'd like to avoid buying MORE tools after all the schitt I've bought these past few weeks. For a little while, anyways :D For the time being, looks like the coat hanger will work. The hole will most likely end up threaded later. Do y'all recommend any specific 4-40 tap, I know those little ones like to break, and I might need to use it again Quote Link to comment Share on other sites More sharing options...
shibiwan Posted May 14, 2015 Report Share Posted May 14, 2015 (edited) Yep, we tap and thread all our lowers when we make them, and put in a 4-40 x 1/8" long set screw to hold the spring in. Any tap will work. It's soft aluminum, but always take your time and do it a little at a time (start the tap, back it out, tap it further by one turn at most, back it out.... repeat until you have around 1/4" of good thread.) Edited May 14, 2015 by shibiwan Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 15, 2015 Report Share Posted May 15, 2015 (edited) 6-32 tap and set screw work well, too. Drill first, with the correct drill bit - #35 or #36 work equally well in this role. Larger diameter, larger allen (not brittle, like the tinyass allen that fits a 4-40, I think it's 0.050"). More meat, coarser threads, easier to work with. I thread all mine with 6-32, unless they were already threaded for 4-40. EDIT - 6-32 set screws are a hell of alot easier to find, too. <thumbsup> Edited May 15, 2015 by 98Z5V Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 15, 2015 Report Share Posted May 15, 2015 I checked all my parts before assembly, and the front and rear detent springs are exactly the same. That's normal - they should be the same length. Quote Link to comment Share on other sites More sharing options...
shibiwan Posted May 15, 2015 Report Share Posted May 15, 2015 6-32 tap and set screw work well, too. Drill first, with the correct drill bit - #35 or #36 work equally well in this role. Larger diameter, larger allen (not brittle, like the tinyass allen that fits a 4-40, I think it's 0.050"). More meat, coarser threads, easier to work with. I thread all mine with 6-32, unless they were already threaded for 4-40. EDIT - 6-32 set screws are a hell of alot easier to find, too. <thumbsup> The standard size detent hole is actually oversized for a 4-40 screw so tapping is easy (you're looking at 50% thread, maybe a little less). Ace Hardware and True Value - easiest places to find fasteners in a pinch. Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted May 15, 2015 Author Report Share Posted May 15, 2015 I honestly didn't even think about opening the hole up for a bigger stud (wait for it....) I'll probably go 6-32, I know I've got that little baby tap, at least. For now, though, my coat hanger mod looks to do the job, as it just happens to slide right in with a light coat of grease with no sideways play and just enough spring tension Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 15, 2015 Report Share Posted May 15, 2015 The standard size detent hole is actually oversized for a 4-40 screw so tapping is easy (you're looking at 50% thread, maybe a little less). Ace Hardware and True Value - easiest places to find fasteners in a pinch. You don't need to drill up if you do 4-40. The standard milling is fine for it, and you just run the tap in it. Works fine. No hazard. 6-32, don't even try to run the tap in the standard milling - you'll be trying to figure out how the fuk you're gonna save your lower, once you break the 6-32 tap off in there. Drill with the #35 or #36 first, a little more than the depth of your 6-32 set screw. <thumbsup> 6-32 is far superior. Fuk 4-40. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 15, 2015 Report Share Posted May 15, 2015 I honestly didn't even think about opening the hole up for a bigger stud (wait for it....) Most women can't take 4 inches... IN DIAMETER!... <lmao> Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted May 15, 2015 Author Report Share Posted May 15, 2015 I know to drill before I tap, I don't want to break it off on my first time :D I just meant I don't have a 4-40 tap, I've got 50 years of random bits from like 4 generations of mechanics and machinists. Where's my smiley bar when I need it.... Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 15, 2015 Report Share Posted May 15, 2015 Where's my smiley bar when I need it.... Obviously, it's eluding you, right now... <lmao> Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted May 16, 2015 Author Report Share Posted May 16, 2015 Dude, when it comes to "misplacing" schit, I'm a professional. Doesn't help that my house looks like Jerry's shop on Shootout Ln.... Quote Link to comment Share on other sites More sharing options...
taffrail Posted June 19, 2015 Report Share Posted June 19, 2015 Received my Matrix upper/lower combo from Chris Riedeman today. Found some surprises. Possibly not for you. 1. Under the rear take down pin is what appears to be a captive detent. 2. The two holes under where the grip goes are not the same size. At least not at the surface. .Appears to be about 1/8th" and then steps down. 3. If someone will tell me how, I will ad pictures. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted June 20, 2015 Report Share Posted June 20, 2015 When you open the reply , you will see at the bottom right , " More Options " open that & on the bottom left side you will see " Attach Files " , chose the file you want , then" attach this file " & once its shows up below the text box , add it where you want . There are other ways , but I don't know them . Quote Link to comment Share on other sites More sharing options...
taffrail Posted June 20, 2015 Report Share Posted June 20, 2015 (edited) Ok. Pictures. Maybe..... Yep. Thanks to survivalshop. A true gentleman. Update. This captive detent is centered on the rear take down pin upper flange or whatever you call the thing with the hole in it and be nice for goodness sake. We are out of our teens....yes? ??? Edited June 20, 2015 by taffrail Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 20, 2015 Report Share Posted June 20, 2015 Click it. Quote Link to comment Share on other sites More sharing options...
AngelDeVille Posted June 20, 2015 Report Share Posted June 20, 2015 He did mention some upgrades in the future, that must be it. Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted June 20, 2015 Author Report Share Posted June 20, 2015 I was wondering when they were gonna move that schit. That solves one issue, anyways. Hey taff, he sent you a lpk, too, right? What does the bolt catch look like? Can you post some pics? BTW, seems like that captive detent in the fcg pocket keeps tension on the rear takedown pin, but it definitely keeps the fit between the receivers tight and play to a minimum. Quote Link to comment Share on other sites More sharing options...
taffrail Posted June 20, 2015 Report Share Posted June 20, 2015 Thanks Dews. One more thing. I have a takedown pin detent hole from the grip and from the rear. I either get to use both or likely get to pick. Depending on what comes in my LPK, I think I'll pick the rear. Time will tell. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 21, 2015 Report Share Posted June 21, 2015 Go from the grip area for that, or you'll have to cut a section of coathanger, piano wire, etc., in order to use that rear entry, and make up the space... Someone mentioned a coathanger earlier - that would have to be a small wire diameter damn coathanger... Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted June 21, 2015 Author Report Share Posted June 21, 2015 The only one I had that was small enough was just skinny enough to slide in with zero play. That being said, I second going up through the grip, that way you'll have proper tension on the detent spring. Quote Link to comment Share on other sites More sharing options...
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