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Posted: 4/22/2023 7:22:56 PM EDT
I never noticed that the front pivot pin hole on my M-16 Colt Upper is not .250
It seems to be 5/16” or .312 I did a little research and I guess there is a .315 front pivot pin???? If this is what I have how do I get it to work with a normal lower?  
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Posted: 4/22/2023 7:28:48 PM EDT
[#1]
You need one of these for a normal lower
ar15sport.com/product/adapter-for-colt-sp1-upper-receivers-ret-sp1adp/ |
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Posted: 4/22/2023 7:37:06 PM EDT
[#2]
If the A-1 style upper is an SP-1 is what I have an SP-2?
How are those bushing installed? Are they a pres s fit or are they loose?? I think I would rather just replace the upper with a normal A2 upper |
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Posted: 4/22/2023 7:40:47 PM EDT
[#3]
They are loose not by much. Once you get it indexed you can hit it with a little JB weld. After that you will forget it's there.
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Posted: 4/22/2023 10:35:11 PM EDT
[#4]
Quote HistoryQuoted: If the A-1 style upper is an SP-1 is what I have an SP-2? 0.315 front pin hole A2 uppers were used on the Sporter II, green label, white label, and some blue label guns. |
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Posted: 4/22/2023 10:54:00 PM EDT
[#5]
I think I'm just going to replace it with a normal A2 upper
AR15sport has opne for $189 https://ar15sport.com/product/complete-rock-river-a2-upper-receiver-arpart-a2stripped/ I don't know if I could get $200 for the Colt Sporter 2 Upper but I might give it a try |
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Posted: 4/22/2023 10:54:00 PM EDT
[#6]
deleated double post
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Posted: 4/23/2023 12:36:54 AM EDT
[#7]
Quote HistoryQuoted: I think I'm just going to replace it with a normal A2 upper AR15sport has opne for $189 https://ar15sport.com/product/complete-rock-river-a2-upper-receiver-arpart-a2stripped/ I don't know if I could get $200 for the Colt Sporter 2 Upper but I might give it a try IM'd you. |
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Posted: 4/23/2023 2:31:57 AM EDT
[#8]
They sell a grommet that fits in there to fill up the dead space around the pin. Works fine for me and I bought a lot in case I lose some.
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Posted: 4/23/2023 11:01:30 AM EDT
[#9]
Quote HistoryQuoted: They sell a grommet that fits in there to fill up the dead space around the pin. Works fine for me and I bought a lot in case I lose some. So are they a pretty loose fit in the hole in the reciever? If so have you ever considered blue loctite |
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Posted: 4/23/2023 1:58:35 PM EDT
[#10]
Quote HistoryQuoted: 0.315 front pin hole A2 uppers were used on the Sporter II, green label, white label, and some blue label guns. This. I had one of the A2 uppers off Sporter 2 blue label lower. |
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Posted: 4/23/2023 5:11:13 PM EDT
[#11]
I had an early Sporter HB with an A2 marking on the receiver but an A1 style early rear sight on he upper... it had the off-set bushing with the opposing screws... after breaking 4 or 5 bushings, I replaced it with an ArmaLite .. should have kept it as it was probably a transition model
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Posted: 4/23/2023 6:14:17 PM EDT
[#12]
I’d send to Braceman or John Thomas and have aluminum dowel pressed in, then machined to be milspec.
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Posted: 4/23/2023 10:11:26 PM EDT
[#13]
Crisis adverted
I just found the bushing on the floor of my vault. I put it back in place and used some blue loctite |
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Posted: 4/24/2023 1:34:34 PM EDT
[#14]
Quote HistoryQuoted: I’d send to Braceman or John Thomas and have aluminum dowel pressed in, then machined to be milspec. Which would be spending extra money to destroy the value of that Colt upper instead of finding a generic A2 upper, |
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Posted: 4/24/2023 2:31:52 PM EDT
[#15]
Quote HistoryQuoted: I think I'm just going to replace it with a normal A2 upper AR15sport has opne for $189 https://ar15sport.com/product/complete-rock-river-a2-upper-receiver-arpart-a2stripped/ I don't know if I could get $200 for the Colt Sporter 2 Upper but I might give it a try Thunder Tactical A2 uppers A2 Forum has been talking about these uppers. |
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Posted: 4/24/2023 4:54:54 PM EDT
[#16]
Quote HistoryQuoted: Which would be spending extra money to destroy the value of that Colt upper instead of finding a generic A2 upper, I don’t personally view those large hole uppers as anything but a nuisance. It’s a shame someone parted it out from a factory Colt rifle, but that ship sailed and Colt gray A2 uppers are not readily available. In my opinion, modifying that to small pin is an enhancement, not a detractor. |
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Posted: 4/25/2023 2:36:05 AM EDT
[#17]
Quote HistoryQuoted: So are they a pretty loose fit in the hole in the reciever? If so have you ever considered blue loctite They slide in and out. If I ever take the upper off and forget its in there at least I'll have extras 
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Posted: 4/25/2023 5:30:36 AM EDT
[#18]
Quote HistoryQuoted: I don’t personally view those large hole uppers as anything but a nuisance. It’s a shame someone parted it out from a factory Colt rifle, but that ship sailed and Colt gray A2 uppers are not readily available. In my opinion, modifying that to small pin is an enhancement, not a detractor. Quote HistoryQuoted: Quoted: Which would be spending extra money to destroy the value of that Colt upper instead of finding a generic A2 upper, I don’t personally view those large hole uppers as anything but a nuisance. It’s a shame someone parted it out from a factory Colt rifle, but that ship sailed and Colt gray A2 uppers are not readily available. In my opinion, modifying that to small pin is an enhancement, not a detractor. As always, it's your property to do as you wish. But, permanently modifying an original is not an enhancement no matter how much you wish it is or how much it personally helps you in this specific endeavor. You can add "I'm sure glad Bubba modified this original and hard to find part!" to the list of things you never hear people say. Ever. H&R is getting close to releasing their A2 uppers, in grey as well. These should be much easier to source in the coming months. |
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Posted: 4/29/2023 10:08:28 PM EDT
[#19]
Quote HistoryQuoted: As always, it's your property to do as you wish. But, permanently modifying an original is not an enhancement no matter how much you wish it is or how much it personally helps you in this specific endeavor. You can add "I'm sure glad Bubba modified this original and hard to find part!" to the list of things you never hear people say. Ever. H&R is getting close to releasing their A2 uppers, in grey as well. These should be much easier to source in the coming months. I’m not talking about a Bubba modification. WECSOG’ing something is different from properly modifying it. And a pressed in bushing could always be removed. |
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Posted: 4/29/2023 11:55:35 PM EDT
[#20]
Quote HistoryQuoted: I don’t personally view those large hole uppers as anything but a nuisance. It’s a shame someone parted it out from a factory Colt rifle, but that ship sailed and Colt gray A2 uppers are not readily available. In my opinion, modifying that to small pin is an enhancement, not a detractor. Quote HistoryQuoted: Quoted: Which would be spending extra money to destroy the value of that Colt upper instead of finding a generic A2 upper, I don’t personally view those large hole uppers as anything but a nuisance. It’s a shame someone parted it out from a factory Colt rifle, but that ship sailed and Colt gray A2 uppers are not readily available. In my opinion, modifying that to small pin is an enhancement, not a detractor. And you are welcome to your opinion. Do you have a big pivot lower? |
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Posted: 4/30/2023 7:30:38 AM EDT
[#21]
Quote HistoryQuoted: And you are welcome to your opinion. Do you have a big pivot lower? I do not. I would own a sp1, but never bought any because I have factory Colt m16s. Other than the SP1, all the large pivot pin guns are the least desirable to me. |
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Posted: 4/30/2023 3:38:26 PM EDT
[#22]
Quote HistoryQuoted: I do not. I would own a sp1, but never bought any because I have factory Colt m16s. Other than the SP1, all the large pivot pin guns are the least desirable to me. Quote HistoryQuoted: Quoted: And you are welcome to your opinion. Do you have a big pivot lower? I do not. I would own a sp1, but never bought any because I have factory Colt m16s. Other than the SP1, all the large pivot pin guns are the least desirable to me. And that "to me" is the key. That's why I still contend that unmolested big hole uppers are more value to those with the appropriate lowers than the expense and time to convert them to small pin specs. Especially when correct small pin A2 uppers are in the pipeline. If you'd still rather cut up an item that's rare and valuable to others in its original form, well you just be you. I prefer to help fellow gun owners whenever possible. |
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Posted: 4/30/2023 4:40:45 PM EDT
[#23]
Quote HistoryQuoted: And that "to me" is the key. That's why I still contend that unmolested big hole uppers are more value to those with the appropriate lowers than the expense and time to convert them to small pin specs. Especially when correct small pin A2 uppers are in the pipeline. If you'd still rather cut up an item that's rare and valuable to others in its original form, well you just be you. I prefer to help fellow gun owners whenever possible. Fair point. I would always prefer a correct milspec front pin upper. If I was in need of a gray upper and could only find a large hole, I’d have no concern or remorse about modifying one. Same re: SP1 uppers on Gunbroker. With milspec front pin gray Colt 604 uppers being somewhat rare, I would not personally hesitate to grab a SP1 upper if at the right price and modify it. But I wouldn’t seek it out and in general I’d rather see original Colt parts stay original. |
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Posted: 6/4/2023 8:52:12 AM EDT
[#24]
I have about a dozen of them available.
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Posted: 6/4/2023 1:41:11 PM EDT
[#25]
Quote HistoryQuoted: Crisis adverted I just found the bushing on the floor of my vault. I put it back in place and used some blue loctite Super Gluing the bushing in place works great, it holds strong, cleans up nice, doesn't alter anything, and can be broke free with a few smacks quickly if needed. |
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