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Posted: 2/22/2005 5:03:40 PM EDT
| Has anyone had problems with mating a RRA lower to a DPMS upper? |
| Is it a problem with getting the rear lug of the upper receiver to seat down in the lower? The RRA lowers seem to be made with just a little extra metal to ensure a good tight fit. I've heard this is the norm with RRA Lowers. I had to apply a little bit of moly grease and "work" the upper and lower together. It required some strikes with the heel of my hand to get it to finally close. You might see a little finish removed from the rear corner's of the rear lug on your upper, but it's no big deal. I tried to seat my brother's 2 different OLY uppers before mine was delivered and it was the same way with them. Hope this helps! |
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Roger on the above comments. Continental Machine, that makes the RR, Stag, and Century lowers, seems to use a different spec for their outside width, than Bushie, DPMS or Colt. Uppers from those brands will almost always overhang the the edges of the lowers put out by Continental. Function is just fine, but the looks bother the hell out of me; so my Conti built lowers all have Conti built uppers on them; except for the one under a Colt M16A1 milsurp upper that happens to be narrower than average, and thus looks just fine 
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I have built that exact combo for more than one customer, and I can say that if 1/64 of an inch of hangover is unacceptable, good luck finding the perfect AR. They all have things that are not perfect when you mix and match. However, they will work just fine, It just depend's on how pickey you are. I have seen factory Colt's, and Bushy's, that have some overhang, it is not uncommon. |
it doesn't bother me to much... I just milled it to match. and really it isn't that noticable. |
Now remember, my upper is RRA and lower is DPMS... so it is the upper that is slightly wider. Some simple grinding. http://www.astraybullet.com/_web/grind1.jpg This is after taking .05 off the left side. http://www.astraybullet.com/_web/match.jpg all in all... it was some uneeded extra work, but I had to do something since the barrel was on backorder. Some finish results of the receivers: http://www.astraybullet.com/_web/receiver.jpg http://www.astraybullet.com/_web/receiverlogo.jpg |
Most of the original finish came off when I removed part of the outer diameter. but to answer your question: If the stock finish is anodized you can do 2 things; 1) Re-anodize, but skip the dye process. 2)Soak it in a mixture of water and lye (or some other acid) for about 10 minutes. This process only removed the coloring, but doesn't remove the "hard coat". If the stock finish is say a teflon coat, then the easiest way is to sand blast with a fine sharp media (like aluminum oxide 140 grit). You can also use the lye and water method as well, but it will take longer. When soaking in acid you'll have to pull the part out and rub it off with a wrag or steel wool and then submerge it again. Its tedious, but is a fairly inexpensive approach. |
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Wow! I didn't realize that you had to be a chemist AND a metalurgist! That sounds pretty darn complicated. I've never been exposed to much information involving aluminum refinishing, but I'm impressed to say the least. Where'd you learn to do this?! I'm a machinist by trade, but this is new territory for me. Thanks for the response! |
I guess that would make us on opposite pages in the same book. I've been messing with finishes for several years (which started in wood working) and I am now trying to muster the skills of a machinist. Its difficult for me to work with metal. Being that I've work with wood, if all my equipment fails I can always go back to a damn knife and some sand paper. Have you ever messed with the program bobcad? |
I thought that it might be DC. Recently got my FFL, and started my on business ( Have wanted to do it for a long time ) Johnson's Custom firearms, but don't have a logo yet , but I like yours. Good Luck with your company. 
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I'll drink to that. I got my type 1 FFL early this year, now I am waiting on them to approve my type 7. and good luck to you as well. |
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