When you resume a paused project

 I cracked open the moving box with "AR280" written on the side, and carefully set out all of the parts from inside it.

There's a half-done lower receiver; an upper receiver; a barrel; two seemingly thicc magazines; three buffer tubes; and bags of screws, pins, and springs.

I found my .280 Remington chamber reamer and started in on the barrel (it was originally chambered in 7mm-08).  As I slowly create small metal shavings from inside the barrel, I start to think that perhaps I'll start over with the lower receiver.

The half-done lower receiver from the box was designed with a bullpup in mind.  However, I'm not sure I like it.

The size of the magazines (meant to fit a .30-06) encroaches on your wrist as you hold the pistol grip.  There are only a few sharpie marks on the aluminum indicating where a push rod or pull cable might be able to go (to connect the fire control components in front of the magazine with the fire control components behind it).

The idea of making it a bullpup was a fanciful dream fueled by cartoonish excess and tacticool superfluousness, but it will not work in this case.  It will just be awkward and heavy... like me.

Thus, I have decided to start over with a conventional lower receiver, based on the AR-10.

It will still need some significant modifications from the original AR-10, but not nearly as many.

The magazine well needs to be enlarged to accommodate the larger cartridge.
The 7mm-08 barrel still needs to be reamed for .280 Remington.
The bolt catch, magazine catch, and magazine release will need to be completely different (due to the magazine almost intruding in on the hammer and hammer pin).
The buffer spring might need to be shortened, based on if the bolt will cycle back far enough to feed the next cartridge.

I did a lot of calculations, measurements, and design work on the magazine well in the bullpup lower receiver already, so I just need to fit those into the new conventional receiver I'll make.

Since my FFL is a type-1 license, this AR280 project of mine will be for my own personal use only (no manufacturing for customers).  ...Not to mention the fact that I'm probably the only person in a 50-mile radius who even has a .280 firearm at all.  😄🤨