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INTLMILCO Receiver Fit, Finish Machining & Anodizing Color Info

Posted by Chris Cox on Jan 5th 2024

Starting mid 2023 - We now make lowers 100% to IMC specs from raw forging to finished product resulting in number of improvements in the accuracy, consistency and fit of the lowers 

Fit, Tolerances and Color

  • Anodizing - Type III Grey and Black anodizing just like the USGI guns
  • Anodizing is grounded/jigged inside the buffer tube threads, there can be a uncoated spot or two in this area as it is covered by the tube itself - it’s not a blemish
  • We are now cutting lowers for a custom tight fit, initial assembly can cause chipping/issues if not properly lubricated - We oil lowers prior to ship to aid in assembly 
  • Oil will darken the grey/black temporarily which is very chalky/light when fresh - Wipe down anodizing with a micro fiber cloth to remove excess oil & lighten after assembly - If your upper is dry & light grey, spray with Sea Foam Deep Creep, let it sit a day and wipe down after the gun is assembled. The real lowers/uppers don't stay light grey as they were oiled/used over time
  • If your lower was not oiled, we suggest spraying with WD-40 or Sea Foam Deep Creep to aid in assembly

Forging Flash, forging dings/dents & M16A1 Profile

  • In addition to cutting for a tighter fit we are leaving the forging flash on to resemble the original USGI lowers, by leaving the flash and not cutting the trigger well smooth - some lowers may have natural blemishes on the bottom
  • Leaving flashing makes cutting forgings a bit more difficult/time consuming, cutting the flash off and making that area smooth/consistent makes machining easier. Consumers relate smooth, sterile forgings to quality which isn't wrong, they just don't look like USGI M16's
  • Our goal is an industrial/military looking lower with a modern custom/tight fit. What we are making is closer in appearance to a USGI lower receiver but with the fit of a custom gun
  • USGI Lowers:
    • Leave the forge flash and dents/dings in forgings are left
    • Trigger well flash is left, meaning any flaws in the triggerwell remain
    • Magwell flare is cut to usgi print vs large modern deep cut chamfers
  • Lastly, our A1 forgings are much nicer than 2019-2022, our E1's will be just as nice
    • E1 lowers will have a cleaner bottom profile like the originals featuring flash removed on back end

We will post photos of the originals we used as examples when setting up these programs at a later date. If you have any questions please reach out to me and I appreciate your business.