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Posted: 11/19/2025 3:35:44 PM EDT
| I have a couple of AR15s that the pins need to be slightly bumped in order to get the pin in. Has anyone ever slightly modified the pin holes in the upper receiver for a better fitup? |
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Whenever anything requires modification, I would modify the cheapest, most easily replaced part. If there is any problem from reducing the diameter of the pin , the pins are cheap and easily replaced with a carriage bolt from the hardware store until you locate and purchase a factory made pin. Receivers are a much bigger hassle to replace. I actually prefer a tightly fitted upper and lower receiver than a loose fitting one. Often using a fine grit abrasive paper (400-800 grig) that will only need to remove some of the parkerizing will get things to fit. Out of around 25 upper/lower receivers that required some fitting of the pins, only a couple required actually removing any metal from the pin. Because the detent keeps the pin oriented in the same way, wth the pins removed I could look through the holes and see where the pin might require removing any metal. Usually the amount of metal required to be removed is far less than people imagine. 8 out of 10 times, merely putting some more taper on the front edge of the pin will allow the pin to start into the the holes and that keeps things nice and tight. |
| Why? If you have to bump them a little bit to open or close but they go without too much argument that's fine. They'll just wear in to a nice fit quickly, in the mean time if they're a little stubborn to get open a mag will start them moving and then you can use your fingers. |
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No I have never modified an upper or lower just the cheap pin. Not hard to see where say a takedown pin needs a little off its shape to fit through the holes just by looking through the holes with the upper and lower together. Old OA lowers needed a pin adjustment/shaping sometimes to get then to go through the holes. Also, I have seen two front pivot pins that had an ever so slight bend in them that caused fitting issues, and the pins had to be replaced. I have always drawn the line if it needed something at If I could push the pin in by hand and pop it out with a slight encouragement of a tool as okay. Never thought needing a tool forcing pin in for engagement was okay. |
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Originally Posted By dbshelton: I have a couple of AR15s that the pins need to be slightly bumped in order to get the pin in. Has anyone ever slightly modified the pin holes in the upper receiver for a better fitup? I've seen both. Neither have ever been a problem to the point I couldn't get the TD pin in or out, I've never bothered trying to fix either other than a little lube and use. |
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Originally Posted By Phillbilly: Conversely, what's a guy do if his sweet dsa middy is a lil loose on his spikes lower ? O remember seeing the accu-wedge ads in SGN, but never grabbed one? Accu wedge will sometimes kinda sorta work. Amazon, ebay, CDNN are just a few places that have them. If the fit is loose at the pivot pin, shims are the better way to fix it IMHO. Old school web page so be prepared to scroll  https://www.triggershims.com/ar_15_shims.php#INDEX |
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Originally Posted By Phillbilly: Conversely, what's a guy do if his sweet dsa middy is a lil loose on his spikes lower ? O remember seeing the accu-wedge ads in SGN, but never grabbed one? Shims, glorious shims. Single best 'quality of life' upgrade I did to my rifle. Went from feeling like a rattling shitbox to a one piece solid rifle I could be proud of. I truly cannot recommend this enough. https://www.ar15.com/forums/AR-15/Pivot-Shims-fixed-my-rifles-side-to-side-play-wobble-super-happy/118-785807/ For my rifle, it was a combo of shiming the front pivot + installing the Wheel Diamond shim in the rear of the upper.  http://www.wheeldiamond.com/ar15accushim.htm https://triggershims.com/ar_15_shims.php#S23 |
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Originally Posted By spydercomonkey: Shims, glorious shims. Single best 'quality of life' upgrade I did to my rifle. Went from feeling like a rattling shitbox to a one piece solid rifle I could be proud of. I truly cannot recommend this enough. https://www.ar15.com/forums/AR-15/Pivot-Shims-fixed-my-rifles-side-to-side-play-wobble-super-happy/118-785807/ For my rifle, it was a combo of shiming the front pivot + installing the Wheel Diamond shim in the rear of the upper. https://i.ibb.co/nz2K78s/AR15-LWRC-Shims-Combo.jpg http://www.wheeldiamond.com/ar15accushim.htm https://triggershims.com/ar_15_shims.php#S23 Originally Posted By spydercomonkey: Originally Posted By Phillbilly: Conversely, what's a guy do if his sweet dsa middy is a lil loose on his spikes lower ? O remember seeing the accu-wedge ads in SGN, but never grabbed one? Shims, glorious shims. Single best 'quality of life' upgrade I did to my rifle. Went from feeling like a rattling shitbox to a one piece solid rifle I could be proud of. I truly cannot recommend this enough. https://www.ar15.com/forums/AR-15/Pivot-Shims-fixed-my-rifles-side-to-side-play-wobble-super-happy/118-785807/ For my rifle, it was a combo of shiming the front pivot + installing the Wheel Diamond shim in the rear of the upper. https://i.ibb.co/nz2K78s/AR15-LWRC-Shims-Combo.jpg http://www.wheeldiamond.com/ar15accushim.htm https://triggershims.com/ar_15_shims.php#S23 He's right. ^^^^ |
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