Happy St. Pat's Day Fellow Gun Lovers. Question for you machinist- gunsmiths. How is the best way to setup to hold a bolt for machining? 4jaw indicated and with collar on bolt end? Fixture idea? Appreciate your methods and ideas. Thanks mucho.
Dan

Since the firing pin hole in the bolt face is seldom dead center, I use a mandrel and roller bearing steady rest for most bolt truing operations.

are you trying to open a bolt face to magnum?

I use a 4-jaw chuck and steady rest.

The LaBounty holding fixture is pretty slick, and will hold just about any sized bolt.

Hey Vapo,
I just want to true it up a touch. I think I will do like Mr Malm does. I had considered his idea. Just like to see how you folks get it done.

On a center fire rifle, the axis runs, theoretically anyway, through the center of the firing pin, through the center of the flash hole in the case, down the center of the bore and out the center of the muzzle. But since firing pins are rarely centered in their bolts, we use the center of the bolt's "tunnel" as our point of reference.

If you were to insert and true up a mandrel into a 4 jaw and then place the pointy end of the live center into the firing pin hole and check bolt body runout, you would more times than not, find it off center, and sometimes by as much as .020 or greater.

It just makes it a whole lot better if you then perform all your machining operations off the bolt body. This is not a hard and fast rule, but for most operations, it works rather well.

If you are chasing that 1000 yard record, then you need greater precision and so you will need to make sure your bolt body is true from one end to the other. This is where the term "sleeving the bolt" comes in... Good luck!