80%

Eh, don't need to go all the way back on a gen 2 lower. Rifle functions perfectly the way i did it

Yup, lower is fine. Milling out the wall between the shelf and the pocket is only really necessary if you're putting in an autosear or if you have a Gen 1 lower. That'll work just fine the way it is.
 
Yup, lower is fine. Milling out the wall between the shelf and the pocket is only really necessary if you're putting in an autosear or if you have a Gen 1 lower. That'll work just fine the way it is.
I just usually start in the rear takedown area with a roughing endmill and plow forward so it only takes me a extra 30 seconds. I kind of like the way it looks without the wall milled though.
 
I just usually start in the rear takedown area with a roughing endmill and plow forward so it only takes me a extra 30 seconds. I kind of like the way it looks without the wall milled though.

I've taken it out on the mine. Gen 1s need it removed for the takedown pin, but Gen 2s already have that area hogged out.
 
So ordered from daytona tactical on the 10th. Got my tracking number yesterday, should be delivered Saturday. Now i need to finish buying all the parts for my next build
 
Any recommendation's on who makes a good reliable paper weight with tight tolerances .
just saw this thread for the first time....but would i be wrong in saying "tight tolerances" depends on the skills of the person doing the milling and drilling?
 
The areas where the upper and lower mate are already milled when you get an 80%. It does vary by manufacturer. Some are sloppier than others. I've taken my BCM upper and tried it on different lowers and some rattle while others don't.
The only milling is for the FCG. I am liking the drop in units as they seem to be of better quality and consistency but are more expensive.
 
The one thing I might add to this 80% thread, is when Drilling the side holes make sure you use new drill bits. I went to a friend's house to use his router and jig, everything was fine until I drilled the holes for the trigger group. he had bits out for me, they weren't sharp at all and I ended up with an oval in one of the holes. Of course the Lower is complete junk now
 
The one thing I might add to this 80% thread, is when Drilling the side holes make sure you use new drill bits. I went to a friend's house to use his router and jig, everything was fine until I drilled the holes for the trigger group. he had bits out for me, they weren't sharp at all and I ended up with an oval in one of the holes. Of course the Lower is complete junk now
You could try over drilling it and fill with a brass rod and re-drill?
 
The one thing I might add to this 80% thread, is when Drilling the side holes make sure you use new drill bits. I went to a friend's house to use his router and jig, everything was fine until I drilled the holes for the trigger group. he had bits out for me, they weren't sharp at all and I ended up with an oval in one of the holes. Of course the Lower is complete junk now
You can get anti walk pins or a drop in trigger. Definitely saveable
 
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I alway drill undersized and ream to final size, I think you get a much more accurate hole size that way. I am using my own fixtures on a Bridgeport with readouts, not sure if you could do that using a jig

You could have someone tig the hole closed and re drill it.
 
The one thing I might add to this 80% thread, is when Drilling the side holes make sure you use new drill bits. I went to a friend's house to use his router and jig, everything was fine until I drilled the holes for the trigger group. he had bits out for me, they weren't sharp at all and I ended up with an oval in one of the holes. Of course the Lower is complete junk now

Don't throw it in the scrap bin just yet. On an "80%" AR10 lower, I had the pin holes go way oversize when I accidentally used a crappy chinesium drill bit when drilling undersize prior to reaming.

I ended up fixing it using some modified 1911 grip screw bushings.....

bushing-3.jpg
 
The one thing I might add to this 80% thread, is when Drilling the side holes make sure you use new drill bits. I went to a friend's house to use his router and jig, everything was fine until I drilled the holes for the trigger group. he had bits out for me, they weren't sharp at all and I ended up with an oval in one of the holes. Of course the Lower is complete junk now
There are kits for sale that you drill and tap for 1/4-40 thread and put an SS insert in that have anti walk pins with them.
I still have a couple of kits for the lowers I have not milled yet.


Malodave
 
There are kits for sale that you drill and tap for 1/4-40 thread and put an SS insert in that have anti walk pins with them.
I still have a couple of kits for the lowers I have not milled yet.


Yeah - those are the ones I tried to find in stock anywhere when I needed to fix that AR10 lower. Nobody had them - I think they might be out of production. That's why I used the modified 1911 grip bushings.
 
There are kits for sale that you drill and tap for 1/4-40 thread and put an SS insert in that have anti walk pins with them.
I still have a couple of kits for the lowers I have not milled yet.


Malodave
Thanks, but too late. I tossed it
 
Don't throw it in the scrap bin just yet. On an "80%" AR10 lower, I had the pin holes go way oversize when I accidentally used a crappy chinesium drill bit when drilling undersize prior to reaming.

I ended up fixing it using some modified 1911 grip screw bushings.....

View attachment 601072
Sorry to revive an older thread but can you explain how you did this? I have some pins that are not in the right spot. But I have a mill and a lathe to help me fix it
 
Sorry to revive an older thread but can you explain how you did this? I have some pins that are not in the right spot. But I have a mill and a lathe to help me fix it

I set the lower up back on the mill, and used a small endmill to bore out the bad pin holes in the proper locations (if you try to just drill them, the drill will try and 'follow' the off center holes).
Then drilled to the 1911 grip screw bushing tap size, and ran the tap through. I also made a shallow countersink the size of the bushing head - this gives the bushing a couple extra threads of engagement.

The bushings were modified by first mounting them to a scrap of aluminum bar, and clamping the bar into the vise. They were then drilled & reamed to 5/32". This leaves just a hint of the original threads behind. Then they were milled flat, and the slot was cut across the top.

After test fitting the FCG, the bushings were re-installed with some red Loctite.

If your pin holes are really far off, and the 1911 bushings are not big enough to correct them, you can also just make bushings of any size on your lathe.

Yeah. Just get another lower and start over.
It's also cheaper just to buy a "100%" lower. But that's no fun - it's a 'hobby' - something to waste time & money on for no real reason.
 
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I may still use the 1911 bushing fix but I installed an anti-walk kit and that helped a lot. I may try to put a shim in the now slightly wallowed-out holes to make sure they don't move together. Thanks for the help all!
 
The one thing I might add to this 80% thread, is when Drilling the side holes make sure you use new drill bits.
Friend was finishing up an 80% with a new drilling jig and old drill bits. he overshot the second hole and the tip of the drill bit snapped off.

Luckily the broken part of the bit ended up logged in the jig, not in the receiver.
 
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