What is Reddit's opinion of Kodiak Cutting Tools KCT136475 USA Made Solid Carbide End Mill, Long, 4 Flute, 1/4" Shank, 1" Length of Cut, 4" Overall Length, 1/4" Diameter?

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https://www.amazon.com/gp/product/B007BTPAZ8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

is the one i used after breaking my first one too. It has 4 flutes instead of 3 like the one from the kit. That just means it will cut smoother, but you will need to go slower. If you are using a router and this kit it can look semi-professional.

That cutting length is too long I think. 80% arms $30+SH makes theirs with a .75 CL. I've grabbed this one from Amazon $21+Prime, but it is a 4 flute and is still 1.0 in CL.

I guess I'll have to buy from 80% Arms

I did get some machining done on the lower yesterday. Here's what I have so far. Drill press is some generic Taiwanese 1HP press, it cuts decently well I guess. Lower is an Anderson 7075, I bought it as a package deal with the jig. The lower I'm cutting is actually a different one from what I got in the package, since the original has a grip screw stuck in it.

One thing I would absolutely recommend is getting a decent end mill. Mine, a Kodiak 4" long, 1/4" dia, 4 flute, 1" LOC cuts through it like butter, and cut right through a bit that I broke in one of the holes. On plunge cuts anyhow, it still chatters a bit when cutting side to side, but that's the press' fault, not the bit. Really wish I knew someone with an actual mill, that would make it 1000x easier.