I have decided that I will build a big bore rifle, so obviously I need to know/understand the correct way to fit the barrel to the action. How exactly is the head spacing done?

Thanks,
Axel

Take it to a competent gunsmith.

Thanks for the suggestion t_bob38. Unfortunately, I want to do this myself. It can't be that hard to do.

Axel

Axel, Mate I've toyed with the same idea myself the best place to start is with some good gunsmithing books but you must be very skilled on the lathe, by the time I worked out all the tools and stuff I would need, I just could not afford the best so I gave the idea away..hope you give it a try...Les

Well, bud, I don't know what I'm talking about, but in light of the disparity of responses, I'll give what I think is the general idea.
You get the one barrel off, screw the other barrel on (chambered and threaded for your action) and check with go/no-go guages to make sure the length of the case and the length of the chamber are within spec tolerances.
If no (and they won't be) you put the barrel on a lathe and "turn down" the shoulder (it's called?) so the barrel will screw in more. Barrels are made too long, just for this reason.
If you go too far, you get the barrel re-reamed deeper and start over.

Well, bud, I don't know what I'm talking about, but in light of the disparity of responses, I'll give what I think is the general idea.
You get the one barrel off, screw the other barrel on (chambered and threaded for your action) and check with go/no-go guages to make sure the length of the case and the length of the chamber are within spec tolerances.
If no (and they won't be) you put the barrel on a lathe and "turn down" the shoulder (it's called?) so the barrel will screw in more. Barrels are made too long, just for this reason.
If you go too far, you get the barrel re-reamed deeper and start over.

That should at least get people riled enough to give you a better answer!

Axel--

Most gunsmithing schools allow 80 hours of class-room and machine time to teach what you want to know. If you're very profiecient in engine lathe operation and have a technical understanding of what headspace is and how it's measured you can cut that in half. To learn it for only ONE action you could probably cut it in half again......it's still too much to cover all the bases by internet.

If it's done wrong you can lose a rifle, and eye, or more.

Mr. Belk,

What are some of the items that I should be very careful about? I seriously want to do the work myself, but I don't want to get injured or killed in the process.

Thanks,
Axel

Axel,
Are you experienced in lathe operation? At least basic turning and threading (by the way, your CZ threads are metric)? Are you experienced in precision measureing techniques? Are you familiar with techniques used to achieve straightness and concentricity in the job? If you can answer "yes" to these questions and more then you probably don't need our help. Otherwise it is difficult for us to explain methodology in a way you would understand. I'm not trying to sound arrogant or pedantic but we don't know where you are starting from.
There have been numerous threads on this forum and others about barrel fitting and chambering techniques. One with reasonable background knowledge will find it all right here! Regards, Bill.

Bill,

I worked for several years as a Manufacturing Engineer. Most of that time was spent in shaft machining. So, yes I am experienced in lathe operation. I have worked with Cinnicinati Millicron, Guildemeister, Heid, Mori Seiki, and Jones & Lamson lathes.

When fitting the barrel what are the key attributes that I need to pay close attention to? How much "stretch" should I machine into the joint i.e. how much shorter should the barrel shank thread be than the depth of the receiver?

Thanks,
Axel

No more than.002". I always cut the tenon .001 short but it is probably fine to make it zero and go for simultaneous contact. Ideally headspace can be established at .002 and this is eliminated by crush when the barrel is tightened up. With belted cases though I cut them at zero since there is always way more than .002 difference on the brass.
So, measure from the face of the receiver to the inner collar. Make the threaded tenon this length(minus.001 if you like). Measure the distance from the face of the receiver to the bolt face. Subtract the first measurement from this figure and the result is the amount you want your guage to protrude when you are finished. Regards, Bill.