jscott
Member
Separated upper from lower for the 1st time. Forward pivot pin came out with no issue. Very difficult to get that pin back in upon reassemble. Took significant force. Anyone else have this issue or a comment?
MP Sport 2 pivot pin trouble
- Thread starter jscott
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Jiggle the gun while you push. May not be lined up exactly. It should snap back into place fairly easily.
I've had a few do that over the years. Some a little and others really bad. I always "polish" the openings with assorted coarseness of silicone rotary tool attachments. I prefer Cratex brand but I guess any brand might be ok. I use those shaped like a bullet. The silicone - based abrasives are very gentle and forgiving. Hard to screw anything up with them.
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If you look at the small end of the pin, you'll note that it doesn't have much of a taper. So, getting the pin back into place means you have to take care to line things up pretty much exactly. If the pin came out easy but takes "much force" to push back in, there's likely an alignment problem. But, it's not unknown for the the spring loaded plunger that retains the pivot pin to cause problems. Also, removing the upper for cleaning usually isn't done. Most of us simply hinge the upper and proceed with cleaning without removing it from the lower. With a bit of hinging the upper it might get easier over time for if and when it's actually necessary to remove the upper. A wee bit of lube probably wouldn't hurt.
Personally, I wouldn't be polishing the parts with any type of powered abrasive tool. Aluminum is soft and you're likely removing the protective anodized surface finish. Lube and pushing the pin flush and the then back might-along with a bit of wear from hinging the upper-make things easier. It's very little movement, but it'll help.
Personally, I wouldn't be polishing the parts with any type of powered abrasive tool. Aluminum is soft and you're likely removing the protective anodized surface finish. Lube and pushing the pin flush and the then back might-along with a bit of wear from hinging the upper-make things easier. It's very little movement, but it'll help.
You could grind on a baby's butt and likely cause no harm with a Cratex. Regarding "removing" the finish, so what? Finish is removed on many parts on weapons that are used to no detriment. A small amount of lube on pins should be sop. No problem with "Aluminum is soft and you're likely removing the protective anodized surface finish. Lube and pushing the pin flush and the then back might-along with a bit of wear from hinging the upper-make things easier. It's very little movement, but it'll help." But that too will "remove" finish, only at a slower rate. Haven't seen many pins and rcvr joints that had much finish left if used.
OK, there ARE various grades of cratex abrasiveness, but using them takes a level of discretion and skill in their use. Having had to tell people that their efforts to "improve" the barrel/frame feed ramps on 1911s (or other firearms/parts) had destroyed the parts, I tend to cringe when someone mentions "Dremel" or other description of the tool.
I don't recall seeing finish wear on the upper pin holes in the ARs assigned to training. During the CQB training module, they did upwards of 1000 rounds per week for 12-13 weeks and cleaned every day.
BTW, if it came out easy-per post #1- I don't see where the fit of pin & bores is the issue.
I don't recall seeing finish wear on the upper pin holes in the ARs assigned to training. During the CQB training module, they did upwards of 1000 rounds per week for 12-13 weeks and cleaned every day.
BTW, if it came out easy-per post #1- I don't see where the fit of pin & bores is the issue.
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mckenney99
Member
Those takedown pins have a groove in them in which the spring loaded detent rides. At each end of the groove there is a slight "divot" to secure the takedown pin from moving in/out. I have seen some of those "divots" deeper than others. Adding a bit of lube to the groove helps tremendously and then moving the pin completely in and out numerous times will help "break" the edges of those "divots" where the detent pin rides. It is not unusual for the first couple dozen times to need an solid bump to get the pin moving until the edges of the "divots" in the takedown pins are broken in.
