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Posted: 9/23/2008 5:31:58 AM EDT
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I completed my first build last night, a surprisingly easy task thanks to the great info here on ARF. But I had one question pop up when I mated the upper and lower halves together. As you can see in the photo below, as the upper hinges down onto the lower, when the front butts together there is a large gap at the rear, and it takes a *lot* of effort to squeeze the rear together enough to insert the take-down pin. It takes so much effort that I'm concerned that it may be putting too much stress on the hinge areas. Is this normal or at least acceptable? http://www.justissoil.com/Pics/AR.JPG |
| Look closely.....where is it hanging up? Is the rear lug too wide to fit into the lower receiver? Are the front lug hole drilled too high on the receiver? Are the lower receiver front lugs drilled too low on the receiver forging. A little careful examination of how all the receiver parts are fitting together should reveil what your porblem is. |
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if you can't find where it's binding up, try this: - get a strip of paper and fish around in there to see if you can catch where parts are hitting parts. - If that doesn't work, try a crayon... where the crayon rubs off, parts are binding. (have to clean it up later though) |
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Ok, I've determined that the problem is the front pin holes are not aligned. If I push out the front pin then lay the upper on the lower and put in the take-down pin I can see that the front holes are off by maybe 1/32 inch. I have a second lower that's not completed yet, I laid the upper on it and inserted the take-down pin, same thing, front holes are off by about 1/32 inch. The offset is with the bottom of the upper's hole higher than the bottom of the lower's, so either the upper hole is drilled too high or both lowers are drilled too low. I have another upper on the way, hopefully it will be here today, when I put it on the lower I guess I'll know who's to blame. |
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