LOL - I know what you really meant to say, but I was just thinking to myself, "It would be fun to make a little shotgun that was actually 410 gauge."
Wire size drill bit to create the barrel?
I'll add something to this. Even if they have a physical address, if it's a questionable company I will look at the Google street view of the address.
It may show up as Bill's Candy Shop, some warehouse with no signage, an abandoned house, etc.
Here's a tip for getting a more accurate gas port measurement. If you have a Harbor Freight nearby, go pick up one of these:
Numbered drill bit set
They're not great drills, but they make for handy measuring tools.
You can then use this chart to convert the numbered sizes to inch sizes.
I'm not sure where you are in Ohio, but here's a list of ranges in Michigan. There's even a couple of 600 yard ranges up north, possibly a good place to do a combination cabin rental/shooting fun time.
Shooting ranges in Michigan
Map of Michigan counties
I used them in my last 2 (did 2 at the same time) builds.
They definitely work, but they are actually 5.1 ounces, not 5.3 as advertised.
The one from heavybuffers is 5.5 ounces.
I wonder how much difference there is with .4 ounces. I wish I would have had both to compare at the time.
Tools, let's see... a small punch, a brass or nylon hammer. You might need a really small (I forget what size) allen wrench for your bolt release(some use a pin, some use an allen screw).
Another ARFCOM guide
Here's a whole bunch of things I bookmarked when I first started doing AR-15 style rifles. The LR-308 lower is essentially the same method.
ARFCOM guide
Vimeo how-to video
PSA video
There used to be a bunch of YouTube videos, but it looks like YouTube took them all down.