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Posted: 7/31/2012 7:19:06 PM EDT
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Hey everyone,
I'm a new ARFCOM user (first post), and built an AR-15 from all of the awesome info on this site, so thanks to those who contributed to all of the threads that I've used (been lurking) to learn about this new addiction. With that being said, I just completed my first build - Mega gator stripped lower CMMG LPK Rainier Arms Combat Series Upper 16" (5.56) 1:7 Twist Magpul ODG furniture and sights Primary Arms Red Dot Optic I really want to go shoot this bad boy, but am having serious problems installing the bolt catch roll pin (I searched the forums, believe me). I'm on my third roll pin, and for the life of me cannot get it to go in all the way. Currently, the 3rd roll pin is as far as I've gotten, with about 1/8" or less of the pin to go. I've read every thread I can find about the subject, and have tried roll pin punches with a soft ended hammer as well as the vice grip method and scratched the receiver through layer upon layer of gorilla tape with both methods. I've used grease, and with the vice grip it was so tight, the pin actually squeaked a terrible metal-on-metal squeal as I tried to get it in. I tried crimping the pin with pliers and it still wouldn't go in. I am wondering if anyone else has had a similar problem with the MEGA gator lower. Perhaps mine was machined wrong? Maybe i'm not hitting it hard enough? Although I nearly knocked it out of a vice block...it looks like the roll pin has passed through the bolt catch itself, but then stops, and I've tried holding down the bolt catch as I hammer in the pin to line up the holes. Need some expert advice. I contacted the dealer who sold me the lower at a gun show but haven't gotten a reply. Thanks for any advice! http://www.flickr.com/photos/75635608@N02/7688660040/ http://www.flickr.com/photos/75635608@N02/7688660238/ |
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Look at the hole. Is the one side smaller than the other? If it is, you have an out of spec lower.
Work the bolt catch as you are tapping the pin in. If it isn't actuating freely the whole time, it is not lined up. I use one of the detent pins from the takedown levers to keep the lever lined up while I tap the roll pin in. |
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Thanks for the quick replies!
Both tabs do have holes, and I can fit a roll pin punch, regular punch, toothpick, allen wrench, etc into the hole. In fact, I tried keeping something in both holes as a guide while I hammered the pin in, and it didn't work. Just tried the bolt catch wiggle while hammering trick and it also didn't work. The pin is past the hole in the bolt catch lever and is already started on the opposite hole on the tab. Frustration! Might have to punch it out and try yet another roll pin... |
| Keep in mind I am by no means an expert (justfinished my first build as well), but I would think filing it down would work. However, before you attempt this you should verify, like the above poster said, that both holes are the same size. I would hate to have you file the pin down only to find out that it is loose on one end. |
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Tape the receiver up up to protect it.
Take the RP and squeeze it a bit in a plier. Don't reuse any RP's from failed attempts. Use a new RP. Make sure that the RP has a slight bevel on the leading end. If not, chuck it up (read drill motor) and gently spin it against a file to create a slight bevel. I said bevel, not reduce OD. Use a "bolt catch" roll pin punch. These are shaved on one side to allow straight-on alignment with the RP. It's a special punch made for driving this particular roll pin. Brownells and ADCO have them. Use oil or grease to lube the pin and pin bore. Use a "slave pin" made from some stock of the correct size. This could be the smooth shank of a drill bit, a nail or a punch. The slave pin comes in from the opposite side and holds everything in alignment while you drive the RP. I tape it so it doesn't bounce out but rather yields to each blow of the hammer. Make damn sure that your spring and detent are in their bore and in there correctly. (checking function with slave pin should be intuitive) Final note: You're beating the hell out of your receiver with 3 tries on this. Consider taking it to a Competent Black Rifle gunsmith. |
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I have a piece of 1/4" flat bar I drilled holes in for the trigger guard pin. I drive the pin through it to pre compress them before installing it in the lower. It helps for that one maybe it will help for the yours.
Also there are pins out that just wll not fit. I ordered bulk 1/16" and 3/32" pins from Fastenal and had to throw them away because I could not get them to fit the holes they were supposed to. Ordered some from MSC different brand and had no problem. Might try getting some pins from a different supplier. |
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