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Posted: 5/22/2014 2:03:32 PM EDT
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Anyone ever have an upper and lower that were so tight to assemble that you had to drive the take down pin with a hammer?
Is there a way to fix this without grinding the heck out of stuff? |
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Quoted:
Anyone ever have an upper and lower that were so tight to assemble that you had to drive the take down pin with a hammer? Is there a way to fix this without grinding the heck out of stuff? Pivot pin yes, tale down pin no. It will wear, personally I would embrace the lack of wiggle |
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Just assembled a PSA lower and a blem upper from.... someone (I cant remember who)
They were so tight I had to use a punch and hammer to get the pin in and out. I sanded the upper a bit where I saw no light through it and the lower and kept driving the pins in and out while watching TV. Now if it pop the front pin I can pull the rear by hand, leaving the front pivot pin in, I have to use a tool to remove the take down pin. I'm sure after shooting it it will loosed up more. |
| When the fit is that tight to start with, it will settle in in a few (maybe a bunch of) open/close or separate/reattach cycles to be extremely smooth but not tight. Rock River's uppers and lowers are milled to have an almost-interference fit and my first RRA was so tight that I needed a light mallet (NOT a hammer) to get the takedown pin out...for about 10 cycles. After that, it was like butter, and it's still an extremely good fitting rifle. |
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Quoted:
I can't speak to what will happen with round count, but psa just replaced an out of spec upper with the same problem for a friend of mine. Will there be any hard anodizing left in the pin holes after 1k rounds, assuming it loosens up? Does it matter? Its aluminum? 
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Quoted:
I can't speak to what will happen with round count, but psa just replaced an out of spec upper with the same problem for a friend of mine. Will there be any hard anodizing left in the pin holes after 1k rounds, assuming it loosens up? If had the same "problem", it wouldn't be out of spec. Out of spec would be if the holes just didn't line up. A tight fit isn't out of spec. |
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I had this problem with my bcm upper on a spikes lower. Had to use a punch to drive the pins out and a rubber mallet to drive them in. All I did was lube them and drive them in and out over and over again till I could do it my hand. It is still very tight but I'd rather have it tight then loose. Just wear them in and it'll be fine.
One other option is the KnS enchanced pins they are something like .005 smaller then regular pins |
| Yes my RRA lower I mated to a Del-Ton upper. The fit was tight between the two and I had to generously lube with CLP and lightly tap the take down pins in and work the upper into the lower. I also generously lubed with CLP the tale end of the upper receiver that goes into the lower to secure the two receivers together and worked them a bit. After shooting a few hundred rounds it loosened up and has been good to go. I don't recommend grinding anything on your receivers. CLP, time, and a good round count should loosen them up bro. |
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