MachIVshooter
Member
7075 is not a weldable alloy.
Your lower is most likely 6061.
80% lower Build problem
- Thread starter Brass2grass
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7075 is not a weldable alloy.
Your lower is most likely 6061.
Brass2grass
Member
Yea I have no idea about that one. Came from a guns show with no markings or packaging.
MachIVshooter
Member
Becoming less and less common, but 6061 was a popular choice for billet lowers, as the material cost is about 1/3 that of 7075. 7075 is about 80% stronger, but 6061 is strong enough for 99% of users and uses.
BBBBill
Member
Some of the older aftermarket receivers were cast 356 - T6.
A few notes.... a drill press is marginal for doing this work. As you noted, a lot of chatter and slippage. The drill chucks just aren't built to take the side loads that a mill is designed for. You need to go very slowly and take very shallow cuts when using a press.
Not sure what you paid for your lower casting. I applaud your tenacity, but I'd likely have chucked it and started over. Tactical Machining currently sells them for 29 bucks when you buy a three pack.
Not sure what you paid for your lower casting. I applaud your tenacity, but I'd likely have chucked it and started over. Tactical Machining currently sells them for 29 bucks when you buy a three pack.
Brass2grass
Member
Started prepping for paint today. Used an auto body prep kit and some steel wool to blend all the welds and scratches. I couldn't for the life of me get the mag well tool marks and gouges to blend all the way so they are still showing a little bit but in not too worried about that right now. I sprayed it in an ultra flat forest green, I'm gonna bake it then clear coat it. Hardware and buffer tube are probably gonna stay black, I haven't decided on that and as for the bolt catch hole not being drilled all the way, I didn't feel like welding the holes up so I just took a Dremel tool and took off a little bit at a time until the hole came through.
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