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Posted: 1/29/2026 8:35:03 PM EDT
[Last Edit: Bye_Felicia][Edited]
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I acquired years ago a "Less than 80%" Grease Gun mag lower. I'd like to finish it out. Attached File Attached File Attached File Attached File Attached File The good; magwell, mag release done and buffer is tapped The Bad; pivot pin/take down holes are not done, neither are the slots for the trigger guard Thoughts on how to finish it out? My understanding is that the pivot pin/take down holes are used on most if not all 80% jigs. Is there a good solution? A company I can send it to to finish out? I don't mind messing up a regular 80% but would hate to mess this one up since I don't think I can get another. |
"My friend, you would not tell with such high zest
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori." -Wilfred Owen
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori." -Wilfred Owen
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Are you sure it is even an "80%" by the way they look at it now? Check out page three, the picture, and dimples in the fire control area. https://www.atf.gov/media/16851/download Have not seen one of the old jigs that would fixture an old style unfinished lower in many years. I always wanted one of the deluxe tannery shop jigs from the early days of cast lowers but wasn't able to get one. |
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Originally Posted By j3_: Are you sure it is even an "80%" by the way they look at it now? Check out page three, the picture, and dimples in the fire control area. https://www.atf.gov/media/16851/download Have not seen one of the old jigs that would fixture an old style unfinished lower in many years. I always wanted one of the deluxe tannery shop jigs from the early days of cast lowers but wasn't able to get one. Ya, most likely ATF would consider it a "firearm" so sending it out is a no go. Guess I'll just try and fixture it up, do the take down/pivot holes and see about getting a jig to finish the pocket and such. |
"My friend, you would not tell with such high zest
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori." -Wilfred Owen
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori." -Wilfred Owen
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Originally Posted By Bye_Felicia: Ya, most likely ATF would consider it a "firearm" so sending it out is a no go. Guess I'll just try and fixture it up, do the take down/pivot holes and see about getting a jig to finish the pocket and such. All of the jigs I've seen help you to finish the fire control pocket, and trigger, hammer and selector holes. And, like you've indicated, they work off of the pivot and takedown hole locations. None of them help with the other parts of the receiver. That lower requires a LOT of other machining to finish. A person with a milling machine and some experience could finish it. But, I don't think anyone makes the jig you need. |
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Originally Posted By Dex223: All of the jigs I've seen help you to finish the fire control pocket, and trigger, hammer and selector holes. And, like you've indicated, they work off of the pivot and takedown hole locations. None of them help with the other parts of the receiver. That lower requires a LOT of other machining to finish. A person with a milling machine and some experience could finish it. But, I don't think anyone makes the jig you need. Originally Posted By Dex223: Originally Posted By Bye_Felicia: Ya, most likely ATF would consider it a "firearm" so sending it out is a no go. Guess I'll just try and fixture it up, do the take down/pivot holes and see about getting a jig to finish the pocket and such. All of the jigs I've seen help you to finish the fire control pocket, and trigger, hammer and selector holes. And, like you've indicated, they work off of the pivot and takedown hole locations. None of them help with the other parts of the receiver. That lower requires a LOT of other machining to finish. A person with a milling machine and some experience could finish it. But, I don't think anyone makes the jig you need. I had come to same conclusion before posting but was hopeful someone would have an idea. At this point I'm going to try and find someone with a mill I could use and try and drill the pivot/takedown pin holes to be able to use a jig to finish the FCG pocket. I'll worry about the other stuff if I can make that happen. |
"My friend, you would not tell with such high zest
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori." -Wilfred Owen
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori." -Wilfred Owen
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They were nice enough to dimple the holes.. that may or may not be enough to land them within the appropriate precision, so IMO i'd follow the ray-vin guide, which if memory serves cuts the front takedown hole and then uses it for reference to cut the rear. you'll need a fixture or fixing setup to hold it to your mill to ensure its perfectly level if you want to go straight through - which seems advisable. once you have the 2 takedown holes you can use relatively normal processes to hog the pocket, cut the FCG holes and then there's a little special work to do on the butt-face but primarily just some holes to cut, nothing challenging. then a little hole cutting and milling on the BHO and you're pretty much there. do you have a 3d printer to make fixtures? |
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Originally Posted By bionicmonkey: They were nice enough to dimple the holes.. that may or may not be enough to land them within the appropriate precision, so IMO i'd follow the ray-vin guide, which if memory serves cuts the front takedown hole and then uses it for reference to cut the rear. you'll need a fixture or fixing setup to hold it to your mill to ensure its perfectly level if you want to go straight through - which seems advisable. once you have the 2 takedown holes you can use relatively normal processes to hog the pocket, cut the FCG holes and then there's a little special work to do on the butt-face but primarily just some holes to cut, nothing challenging. then a little hole cutting and milling on the BHO and you're pretty much there. do you have a 3d printer to make fixtures? I do, a Bambu Labs P1S. Your thoughts above are pretty much mine on how to finish it out. |
"My friend, you would not tell with such high zest
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori." -Wilfred Owen
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori." -Wilfred Owen
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Besides the Tannery shop another company I think called CNC guns or gunsmithing used to sell a mill jig. There was one other company's jig that I used to complete an old unfinished lower, but I can't remember who made it. It had less features and needed more skill to set up and use. |
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Originally Posted By Bye_Felicia: I do, a Bambu Labs P1S. Your thoughts above are pretty much mine on how to finish it out. https://www.thingiverse.com/thing:6655978 this is what I created from a source file that only fit milspec and I tweaked it - you may need to tweak more for the grease gun aspect and also do an x-y compensation due to the length of the run if your material shrinks - e.g. i use ABS primarily and I found that 100.4% x-y is needed for the pin holes to line up correctly to where they should be in the model. your mileage will vary, but well worth calibrating your flow, then printing a 200mm long rectangle and measuring to come up with x/y offset if you can before investing the filament for a fixture otherwise accuracy may suffer. I use a 2x 1/4" nut and screw to hold the receiver to one half for side operations, and in theory you should be able to use this type of approach for butt-face operations also, though I havent tried that myself. I would avoid PLA unless you plan only small operations, the heat will get to it.. PETG, ABS and especially PET-CF work well for fixtures. my current set is PETG. |
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Originally Posted By Bye_Felicia: I had come to same conclusion before posting but was hopeful someone would have an idea. At this point I'm going to try and find someone with a mill I could use and try and drill the pivot/takedown pin holes to be able to use a jig to finish the FCG pocket. I'll worry about the other stuff if I can make that happen. If you want to roadtrip to GA, I'll plop ya in front of a mill with the proper tooling and make sure you don't fuck it up.....  I have 5 or 6 of the lowers in various guns.....and I have one 80% I haven't got around to finishing.....just sold my last 100% to a long time customer who had a DI45 on it as his got stolen......
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Originally Posted By Mad-Machinist: If you want to roadtrip to GA, I'll plop ya in front of a mill with the proper tooling and make sure you don't fuck it up..... I have 5 or 6 of the lowers in various guns.....and I have one 80% I haven't got around to finishing.....just sold my last 100% to a long time customer who had a DI45 on it as his got stolen......Originally Posted By Mad-Machinist: Originally Posted By Bye_Felicia: I had come to same conclusion before posting but was hopeful someone would have an idea. At this point I'm going to try and find someone with a mill I could use and try and drill the pivot/takedown pin holes to be able to use a jig to finish the FCG pocket. I'll worry about the other stuff if I can make that happen. If you want to roadtrip to GA, I'll plop ya in front of a mill with the proper tooling and make sure you don't fuck it up..... I have 5 or 6 of the lowers in various guns.....and I have one 80% I haven't got around to finishing.....just sold my last 100% to a long time customer who had a DI45 on it as his got stolen......Damn, I may take ya up on it. |
"My friend, you would not tell with such high zest
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori." -Wilfred Owen
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori." -Wilfred Owen
|
I'd get it working 1st, then worry about the niceties like takedown pin detent holes and BHOs. Get the takedown pin holes drilled, then get it in a jig and route out the fire control pocket. Get it working w/ yer upper and then do the little stuff. |
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Originally Posted By Stretch762: I did a 0% years ago and used the Ray-vin instructions (54 pages IIRC) I made a pair of side plates to hold the lower. I don't remember where I got the dimensions for the side plates. Dimensions for the side plates are in the addendums at the back of the instructions, along with a couple of other fixtures. Ray was THE MAN on machining a forging! |
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