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Changes to scratch built lower design.

3K views 20 replies 6 participants last post by  joezx10r 
#1 ·
Here's the new design with a few changes made. The mag well has been shortened and radiased so the rifle can be tilted forward and cleaned like normal and the mag well has been angled. Also the grip area and rear mag well block have been modified to except stock AR and aftermarket trigger guards. Working on different variations and getting the prints made up if anyone wants them.
 
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#2 ·
Ingenius !!! My hat's off to ya. I would really like to have some prints!

Why didn't I think of that??? LOL!
 
#15 ·
This is AWESOME!

What kind of tolerances should I expect to be within when milling all the parts of the receiver?
Well it depends if your going to use flat head screws or buttons. When I built mine from the original prints I changed it to flats with countersinked holes and tried to keep them as tight as possible but had some fitment issues during assembly with the rear mag block and fire control side plates binding when the screws are tight. Clearance the shoulders back a few thousands under sized and all is good. The hole diameters where it bolts to the upper and the fire control dimensions should be kept within original AR print specs but other than that its up to you.
 
#16 ·
There are guys who can center-punch and drill a hole to within .005". The damned drill bits always fail to cooperate with me, though.

The old bench-work method is to only lay out and drill one fastener hole. Use that to bolt the pieces together - you can use superglue to help keep them from slipping - and then lay out, drill, and tap the other holes. Use acetone to dissolve the superglue, then open up the holes on the top part so the screws will go through, countersink or counterbore as needed, done.

The other trick is, if you're trying to get a bunch of bolted-together bits to all line up neatly, is to leave a bit of extra stock on the edges. You can then mill, belt-sand, or spindle sand the stack so everything looks neat. Those reciprocating spindle sanders can do amazing jobs on internal curved surfaces.

Of course, if you're using CNC you don't have to worry about that sort of thing...
 
#20 ·
Rivets!

It just occurred to me that, with a few modifications to your design, you could use sheet steel for the side pieces, a few machined bulkhead pieces, and rivets to hold it all together.

Perhaps I need to change my medication. The Voices are getting strange lately...
 
#21 ·
It just occurred to me that, with a few modifications to your design, you could use sheet steel for the side pieces, a few machined bulkhead pieces, and rivets to hold it all together.

Perhaps I need to change my medication. The Voices are getting strange lately...
Yup that should work. I know how you feel I had to take a break from the designing for awhile I started getting burnt out on the Ar mods:loopeye: but need to get back to it for a pistol cal bolt together and also the 10/22 receiver.
 
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