POTD: The Turnbull TAR-40 – Case Colors on a Black Rifle

Welcome to today’s Photo of the Day! Here we have an AR that looks like it wandered in from 1890. Doug Turnbull built his name up in Bloomfield, New York, doing bone charcoal color case hardening and period correct restoration work on Colts, Winchesters, Parkers and Foxes. The TAR-40 is what happens when a man with that skill set looks at a DPMS pattern 308 and decides it could use some help.

There is a hard engineering reason this rifle came out the way it did. You cannot color case harden aluminum. Case hardening is a carburizing process that drives carbon into the surface of a low carbon steel, and the colors come out of the quench. So if Turnbull wanted case colors on an AR, the receivers had to be steel, and they are, cut from 8620 billet, upper and lower both. Add walnut for the handguards, grip and buttstock and you land around twelve pounds bare. That is roughly four pounds over a normal AR-10, and it is the price of admission for that finish.

Turnbull built about a hundred of these before the model went away. This one wears a bullet button, so it was put together for California.

While we are here: if anybody at Turnbull is reading this, I have a Spencer 1890 sitting around that could use some love if you want to team up on something.

Most of our POTDs utilize images from our friends at Rock Island Auction Company, the premier firearms auction in the United States. Take some time to browse their current auctions – who knows, maybe you’ll find a piece of history to take home!

“Turnbull Manufacturing Co. Casehardened TAR-40 Rifle.” Rock Island Auction, www.rockislandauction.com/detail/4097/553/turnbull-manufacturing-co-casehardened-tar40-rifle. Accessed 10 Sept. 2026.

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