Headspace?

[J.Murphy]

I am chambering a rifle for the 40-60 Maynard cartridge tomorrow using Graf 30-40 Krag brass. How much clearance should I leave between the cartridge base and the bolt face? I have Go/NoGo gauges for most of my reamers, but there is no factory brass for this cartridge and all brass must be converted from something else. I have 300 pieces of this brass, so that is what this chamber will be cut to fit.

[art ruggiero]

reach out to frank monikowski v bull he built one

[Clarence]

Why not measure that brass, find the thickest rim, and add 0.001-0.002"? f course, that assumes you have a lifetime supply of that brass.

Since you apparently have the reamer, you can always go a couple of thousandths deeper later if you get a thicker batch of brass.

Clarence

[George Babits]

I'm no gunsmith but, unless I am mistaken, rimmed cartridges headspace on the rim. The 40-60 Maynard uses 30-40 brass. Therefore, the go / no go headspace gages for the 30-40 should be appropriate. I should also like to point out that what is called the 40-60 Maynard these days is not the same as the original (real) 40-60 Maynard. It is actually what was called in the 1960's and '70s the 40 Krag. I had Dick Hoch build me one on a Ruger #3 back in the late 1970s.

George

[J.Murphy]

Thanks for the suggestions, I used Clarence's idea and added .002" to the thickest rim. The 40-60 Maynard or 40 Krag, can be made from .303 British, although the .303 is shorter. In my case it was easier, because the reamer I used was from Elk Ridge Reamer Rentals, it was the only 40-60 Maynard reamer I could find, although I could have possibly had a custom reamer made, I was hoping to avoid the wait. This reamer unfortunately was resharpened and the cartridge rim section was cut .040" below Krag brass width. When I began to check for headspace, the brass wouldn't fit in the chamber. I thought that perhaps they had sent the reamer for .303 British, but it wasn't correct for that brass either. I called Elk Ridge and was told the mail box was full, after I checked reviews online, I found only bad news. I should have checked this before, but I didn't. I used a boring tool to cut the rim recess separately, although it shorted the OAL somewhat, I have to cut the length anyway. I have always bought my reamers before, but there appears to be a disruption in the reamer business, and this was the only 40-60 Maynard I could find.