Chambering ?????

[msr243ai]

HI all !!!

I am wanting to do my own barrels, threading, chambering ,crowning, the whole kit N Kaboodle...Just need some info. When I set my barrel. A .224 bore Hvy Contour Shilen CM In the lathe. I have a Manson Floating Reamer holder. With a Manson reamer (22-243 Win). How far do I need to insert the reamer to get proper headspace ? I was told that ALL centerfire guns there is supposed to be .125 or 1/8 inch of case sticking out the back end of barrel..Is this true for ALL centerfires ? Also, do you guys thread first then chamber or chamber then thread last ? All guidence is helpfull. Thanks a lot MSR243ai..

 

[skinnj1]

No offense intended but buy Hinnant's book, the pictures and descriptions will get you there if you know how to run lathe and if not, it will give you an idea of how much you need to learn........

 

[jscandale]

How far do I need to insert the reamer to get proper headspace ? I was told that ALL centerfire guns there is supposed to be .125 or 1/8 inch of case sticking out the back end of barrel..Is this true for ALL centerfires ? Also, do you guys thread first then chamber or chamber then thread last ? All guidence is helpfull.

Thread first then chamber! You will absolutely need the threads in order the check headspace. As far as your question about how far should the case stick out of the bbl, that is the part of the case that is enclosed by the bolt when the rifle is assembled. With no intentions of insulting you in any way, your question raises an obvious question about your understanding of the fundamentals. There are several good how to books on this very subject. I would strongly suggest that you check it out. This is not something that want to find your way in doing due to the eminent danger that can be innocently built into your project.

Safety first!!
JS

 

[Gundoktr]

Jscandale:
Not to insult you either but some of your answer is dead wrong or at least misleading. You DO NOT need to thread first, you do need a shoulder from where to measure your headspace from. In practice, threading last will ensure the barrel threads remain concentric with the chamber in some cases of the bore being out of concentricity with the OD of the barrel, this will depend a lot on your method of holding and mounting your barrel. All chambers DO NOT have the case sticking out of the barrel. Remingtons have a counterbore the case is enclosed in, however it does stick out. Mausers, Winchesters, Sakos and others have the case sticking out.

Give the guy a break, some body had to start somewhere, Where did you get your start?

 

[msr243ai]

Thanks Gundoktr,jscandale.......I need to find that book sounds like. Yes this is all new to me (gunsmithing) I am an avid shooter all year long. Have been shooting since I was young. Also, have been operating a lathe for about 10 years. So yeah I know what I am doind on my lathe. Just not the smithing yet but, I want to learn how to.....Thanks again..

 

[jscandale]

Jscandale:
Not to insult you either but some of your answer is dead wrong or at least misleading. You DO NOT need to thread first, you do need a shoulder from where to measure your headspace from.
Give the guy a break, some body had to start somewhere, Where did you get your start?

Thanks, I'm glad you are into splitting hairs. My main concern to msr243ai was to ensure safety. There are several ways to skin a cat, and I am quite sure that he will find his own way that will work just fine.

JS

 

[rayjay]

By using a depth mic you can measure from the front of the receiver down to the bolt and make a drawing that will show you what you need to know. You do need to remember to add the thickness of the recoil lug and whatever clearances you decide to use.

You will need to measure :

#1- to the 'nose' of the bolt
#2- to the recess in the front of the bolt that the base of the cartridge actually sits in
#3- to the front of the locking lugs

What I did is make an internally threaded sleeve that screws onto the bbl threads. With the sleeve in place I can measure down to the various machined surfaces of the tenon and to the back end of the go gage. Subtract the length of the sleeve and you have the exact dimensions of the tenon. I normally leave the torque shoulder a bit long, say .020". Once I get the back end of the tenon cut to specs I then screw the receiver onto the bbl and check the headspace I then move the torque shoulder forward a few thou at a time until the headspace is where it needs to be.

 

[rayjay]

If you go to the Stiller site they have drawings for their receivers. A drop port action uses a Remington pattern bolt so you can get an idea of what you are trying to accomplish and what your drawing should look like.

You MUST always measure your own action when dealing with a mass produced action.

 

[Rustystud]

Suggestion:

Whether you are a master machinist or newbe there is no better way to learn chambering than from and experienced person. Find a qualiified mentor or take a NRA short course in chambering. It will be the best lesson you can have. There are many ways to skin a cat and after skinning a few cats I quickly found some ways to be much better than others. Books and the internet are great but as with real life there is a lot of BS out there. You want your chamber to be both concentric and co-axial with less than .0002 tir. Your headspacing has to be +/-.00175 to fall in the .0035 SAAMI spec.
Nat Lambeth

 

[shortgrass]

After reading through this thread, I'd take 'rustystuds' advice. There's no substitute for hands on, qualified instruction.