Finishing AR-15 80% Lowers

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  • clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    If you are going to have a completed 80% lower anodized do you need to ream the safety/selector and trigger/hammer pin holes slightly oversize to account for the thickness of the hard coat anodizing? The 80% lower drill bit set I used contains a 5/32" trigger/hammer pin drill bit and a 3/8" safety/selector hole drill bit. On a 7075 lower the bare aluminum holes these bits make are very snug; I'd hate to have to ream an anodized hole out (to the bare aluminum) to get std. pins to fit. Any advice?

    Couldn't say without having the lower in front of me. The spec for the safety bore is .375 and the FCG bores are .155.

    I would ask the anodizers how thick the anodizing is and make corrections. The safety bore does not fail till it reaches .380 and the hammer and trigger bores don't fail till .163.

    L
     

    94hokie

    Active Member
    Mar 29, 2015
    832
    Severna Park, MD
    If you are going to have a completed 80% lower anodized do you need to ream the safety/selector and trigger/hammer pin holes slightly oversize to account for the thickness of the hard coat anodizing? The 80% lower drill bit set I used contains a 5/32" trigger/hammer pin drill bit and a 3/8" safety/selector hole drill bit. On a 7075 lower the bare aluminum holes these bits make are very snug; I'd hate to have to ream an anodized hole out (to the bare aluminum) to get std. pins to fit. Any advice?

    Hard coat anodizing should add about .001-.0015'' to the edge of a hole, so you are looking at .002-.003'' shrinking in the diameter of a hole in the receiver
     

    DutchV

    Ultimate Member
    Jul 8, 2012
    4,702
    If you really don't want a serial number, some anodizing can be done at home. Of course, it involves electricity and acid, so it's not quite as simple as dropping a package in the mail.
     

    Allen65

    Ultimate Member
    MDS Supporter
    Jun 29, 2013
    7,063
    Anne Arundel County
    If you really don't want a serial number, some anodizing can be done at home. Of course, it involves electricity and acid, so it's not quite as simple as dropping a package in the mail.

    You can buy home anodizing kits here:
    https://www.caswellplating.com/anodizing-products.html

    It's a bit pricey for one or two lowers, though, and requires handling (and legal disposal of post-anodizing) strong acids.
     

    marcwells

    Member
    Aug 7, 2022
    19
    United States
    So I bought before I thought and ended up with two Matrix Arms AR-15 80% lowers that are unfinished. The black ones were back ordered, there was a sale, and a coupon for free shipping.

    After they shipped, my brain finally decided to look up the price of cerakoting and they are fair prices based on the process and time involved. That being said I'm curious, are there more DIY focused finishes that work well? I own the tools necessary to finish the milling of the lowers and just think it would be cool to be able to say I also applied the finish.

    I looked up cerakoting and found some YouTube videos of people doing it themselves. I also found some websites listing everything from standard spray paint, bbq paint, engine enamel, leaving it as is, and DIY anodizing. Besides the anodizing (because I'm not playing around with acid or lye) or leaving it as is, are any of the other suggestions actually good ones? Any other methods that produce good results?

    Has anyone done cerakoting at home 80% lowers? I saw one video where it was applied with an air brush, which looked easy enough to attempt, and the result actually looked good.
    I have a PSA AR-10 .308 that I have use for hog hunting and plinking steel. It is not a precision rig and was not bought to be used as one. My problem is I have enough slop and play between the upper and lower than even when my bipod is locked as tight as possible I still have side to side play. I tried installing an Acuwedge but could not get the upper to closed enough to get the take down pin in. Is there any other option our idea for eliminating our at least reducing the shop between the upper and lower?
     

    E.Shell

    Ultimate Member
    Feb 5, 2007
    10,242
    Mid-Merlind
    Shave a little at a time off the bottom of the AccuWedge with a sharp razor blade to allow the rear pin to engage.
     

    Allen65

    Ultimate Member
    MDS Supporter
    Jun 29, 2013
    7,063
    Anne Arundel County

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