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Posted: 8/26/2024 9:47:10 PM EST
[Last Edit: bionicmonkey]
Bought some of these billet lowers from durkin tactical .. milled several out before i realozed this defect in one. It was more subtle as just a deformation and crack but when it tried to install the buffer and spring and push it back it got worse. Basically it looks like the hole was cut wrong (at a slight angle tilting forward, and deforming that tiny wall between it and the rear takedown pocket) and now the detent is being pushed by the buffer spring forward and stops the upper from being able to be put into place because it is too far forward.
Any ideas on how to save the lower other than removing the detent and running it with no detent or back to the mill with another lower?  Attached FileOthers from this brand were super close and slightly bent but the above one was fully cracked and tilted.  Attached File |
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MN, USA
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Posted: 8/26/2024 9:58:55 PM EST
[#1]
removing the detent and running it with no detent I vote this. It will only surprise you once 
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Posted: 8/26/2024 10:11:56 PM EST
[#2]
 Attached FileCompare to a PSA lower how much thicker that wall is - 2 full threads in the psa vs 1 in the 80 from durkin. |
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Posted: 8/26/2024 10:12:16 PM EST
[#3]
You could install a plug in the existing hole and then drill a new hole in the correct spot, but as cheap as they are not sure if the time is worth just buying another
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Posted: 8/26/2024 11:37:08 PM EST
[#4]
I vote for running a buffer that doesn’t require the detent like the JP.
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ME, USA
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Posted: 8/27/2024 12:22:00 AM EST
[#5]
Quote HistoryOriginally Posted By BigPolska: You could install a plug in the existing hole and then drill a new hole in the correct spot, but as cheap as they are not sure if the time is worth just buying another Or you can open it up and then use some bisonite or marinetex bedding material. Coat a drill bit of the proper pocket size with release agent, and use it to form the pocket. |
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Posted: 8/27/2024 12:25:59 AM EST
[Last Edit: Wangstang]
[#6]
Easiest option is just leave the detent out.
Oversize bore the hole and sleeve with stainless tubing that is press fit or marine text bonded. |
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Posted: 8/27/2024 5:51:01 AM EST
[#7]
The hole is supposed to be angled. Sorry, no good idea for a simple fix.
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Posted: 8/27/2024 5:59:48 AM EST
[#8]
Quote HistoryOriginally Posted By j3_: The hole is supposed to be angled. Sorry, no good idea for a simple fix. This.^^^ Building the edge up with JB Weld or Devcon aluminum putty would likely work. I'd use a detent to preserve the desired opening and definitely use a release agent. |
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Posted: 8/27/2024 6:28:01 AM EST
[Last Edit: bionicmonkey]
[#9]
Quote HistoryOriginally Posted By hamptonyellowdog: I vote for running a buffer that doesn’t require the detent like the JP. oh shit.. i totally didnt think of that.. I think I have a law folder somewhere... brb ETA- BINGO!! No detent in the frame. .. just need to transfer the folder to this frame.  Attached FileETA 2 - interesting how there's only 1 thread visible in this bushmaster frame. seems like perhaps inconsistent pocket cuts at the rear takedown vs inconsistent hole placement. |
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AK, USA
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Posted: 8/29/2024 9:52:58 PM EST
[#10]
Or you could just completely refill the hole with aluminum rod, hold in place with epoxy, and recut the buffer retainer hole. The epoxy should hold the crescent moon shaped aluminum filler in place.
Single point chase the receiver extension threads and Bob's your uncle. |
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Posted: 8/30/2024 3:11:57 AM EST
[Last Edit: IdahoPCCinc]
[#11]
OP....was the pocket pre-milled....or did you go too far back when you milled it ??
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Posted: 8/30/2024 3:13:48 AM EST
[Last Edit: IdahoPCCinc]
[#12]
Double tap. |
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Posted: 8/30/2024 7:25:39 AM EST
[Last Edit: bionicmonkey]
[#13]
Quote HistoryOriginally Posted By IdahoPCCinc: OP....was the pocket pre-milled....or did you go too far back when you milled it ?? . it was an 80 with the rear pocket (just at the takedown pin area) pre-milled and anodized. The 2nd pic in the original post shows the ano'd pocket where it is also thin is a 2nd still un-cut 80 from the same batch. eta here's an image from their site - which, now that im paying super close attention, actually shows the thinness at that rear area. 
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MN, USA
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Posted: 9/4/2024 9:05:53 PM EST
[#14]
I bought a 3-pk of 80's from RTB earlier this year and they don't have a whole lot of room either
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OH, USA
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Posted: 9/7/2024 11:48:16 AM EST
[#15]
Instead of drilling a deep hole for the router, you can use that existing space at the rear for the router.
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Posted: 9/7/2024 12:18:56 PM EST
[#16]
Quote HistoryOriginally Posted By RD20: Instead of drilling a deep hole for the router, you can use that existing space at the rear for the router. Thats at shelf height. So there will need to be a plunge somewhere. Personally i drill out as much meat as possible before going in with the roughing mill and then the end mills. |
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Posted: 9/10/2024 9:15:25 PM EST
[#17]
Not the easiest solution, but it's not an impossible challenge. The best way would be to drill it out, maybe even tap it and insert a plug. Then Redrill the hole correctly.
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NC, USA
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Posted: 9/11/2024 4:36:57 PM EST
[#18]
The hole is supposed to be at a 6° angle/
The web should be about 0.050 inch thick at the top. |
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