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Posted: 3/12/2011 7:54:17 AM EDT
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Question- I have a Colt preban lower that is Colt gray and does not match the new black BCM upper I purchased to go with it. The lower is almost new condition (with a ground down sear block). I figure instead of hitting it with Cerakote, I should just send it to Victor to be refinished the new milspec black color, but I'm concerned if that process will change the dimensions on the holes in the lower causing issues. Is this something to worry about? |
| Removing anodizing takes off about .001" of material and replacing it adds about 1/3-1/2 of that back. You'll lose some but nothing to worry too much about. You should send both receivers in to have them matched though. If you really wanted to go the extra mile you could send the lower to M60joe first and have him remove the whole sear block and weld the hole first. |
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I had my upper, lower, and rail done in US Anodizing's Magpul FDE and I can tell you that the prep part of the process does remove the old anodizing and the new anodizing that was applied was not the same thickness as the original. I know this because on my URX II with the intergrated flip up front sight, it was very stiff to open. Now, with the new color, it opens almost too easy, and has a lot of play in it now. Also, when installing my Geiselle trigger, I pushed the pins in by hand; no tapping with a hammer required.
If you go with the black, it might be the same thickness as the original, and you won;t have to worry about it. At any rate, if you go with US Anodizing, be prepared to be without your parts for 5+ weeks. FYI |
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T3 hard coat offers the thickest build up of the anodizing types but you'll probably never get it built back to the exact same dims it originally was. Like I said you can figure on losing maybe .0003 from each surface as a minimum but look more toward .0006-.001”. Doesn't sound like a lot but when you're talking about a hole or a slot it can be noticeable especially on tight tolerance things like the sight matt58 just mentioned.
If I were getting a lower done I’d just use KNS pins after the refinish to make sure the slop was taken care of. Other than that you really shouldn’t see too much difference as you should still be within tolerance from original. |
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