[moleman]

Picked up a Mossberg M72 30-30 five or so years back super cheap because it didn't cycle. It looked like it had never been cleaned inside and a thorough cleaning was all it needed. In order to deer hunt with it in Michigans Limited Zone it needs to be chambered in a straight walled cartridge at least .35" dia and with a case between 1.16" and 1.8". I was debating on rebarreling it to 445SM but think that 375 Winchester or a 1.8" version 375 M3 (MoleMan Mjollnir). Likely could use a 375 Win reamer but that would leave a long jump to the rifling, besides where's the fun in that. Using the SAAMI spec chamber drawing and a few dummy rounds a reamer print was made for a 1.8" case length. A reamer blank was turned from O1,fluted, hardened, ground and sharpened.

 

[moleman]

Didn't take a pic of this reamer getting fluted, but here's the setup I use. Profiling the blank is more work for me than fluting, so I cut 6 flutes, but a D type reamer would work as well. Cut the flutes .005"-.010" below centerline so they'll cut.

Already had a .375" 1:12" blank long enough for a 20-21" barrel, so it was set up in a lathe and the reamer tested by short chambering the barrel blank. The Mossberg barrel has a hood which extends past the chamber, so once the barrel threads and hood is cut it can be finish chambered. I'm thinking about making it an octagon barrel, which would mean making a new forearm and forearm cap and tenon because the Mossbergs were round barreled and used forearm bands. That's were I am as of today. It will likely take a while to get the barrel profiled (round or octagon) and any other parts made.

 

[Tommo]

Moleman you are a genius! Wish I had your talent.

 

[moleman]

Thanks Tommo, I'm mostly just stubborn and have lots of spare time. It took 3 attempts to make that reamer. 1'st one I inadvertently cut the flutes slightly too deep (top reamer) so I never hardened it. 2nd attempt turned out great (bottom reamer), but the O1 didn't fully harden in the leade area. After about an inch of barrel the reamer showed wear. If hardened correctly they should last for many barrels. So I broke down and bought the recommended AAA quench oil for O1 steel (https://www.amazon.com/Parks-AAA-Quench-Oil-Gallon/dp/B07V5R4X1Q ) as I've always had reamers intermittenly not harden correctly. Sort of a frustrating thing when you've spent hours on making something and the heat treating fails. Wish I'd of bought it sooner. The AAA oil hardly smoked where as the used motor oil I've been using for years usually puts out enough smoke to put a decent haze in my 30x40 shop. The reamer came out looking cleaner than with the used oil and nice and hard. It looked the same after the test chamber as it did after making the last pass with the tool post grinder. The AAA quench oil is quite a bit thinner than motor oil, very similar in feel to kerosene.

 

[Tommo]

You have allot more patience and determination than I do. I woud not even know how to start making my own reamers, yikes!

 

[moleman]

Had a little more shop time. Got the blank turned between centers down to a uniform diameter, the the chamber end turned down to .796" and threaded 24TPI. There is a hood cut on the factory barrel, but if cut right now it would make it harder to hold for milling the flats into so it will get done later. I'll torque the barrel on, mill a flat at TDC and use that to set up the barrel in the mill. Also picked up a Marlin 1894 octagon forearm cap and mounting tenon.