Getting ready to cut my first Remington 700 breech. Check numbers please...

[Taylorbok]

After reviewing all the input from everyone, how about this for some final numbers:

Headspace location from shoulder: 0.957"
Tenon length: 0.947"
Headspace gauge protrusion past tenon: 0.010"
Bolt nose to counterbore clearance: 0.018"

Tony.

Your Counter bore is to deep, that's gonna give you more unsupported case.
BF to nose is .145" and you've already got the .010" clearance built in since you shortened .010 off the whole length.

 

[swd]

There's a lot of overthinking going on here.... Put the bolt in the action and recoil lug on the front, measure to the B dimension from the front of the lug to the bolt lug B and subtract off whatever you like for clearance. I like .007", .010" is fine too. Cut and thread the tenon. Measure the actual bolt nose B2 and touch off at the back of the barrel and cut that actual linear dimension and it will be the same clearance as B. Open your I clearance to whatever you want, I like .007"-.010" and your done. If you want the recoil lug to locate a little better set the tenon a little larger in that area for .001"-.002" or so.

If you're someone who wants things tighter realize there is a small radius on the bolt at the corner of the bolt lug and nose and you'll need to break that corresponding edge on the barrel which I do anyways to keep brass from shaving along with edge of the chamber. And after that I give it a quick polish with 320 or 400 wet with oil.

 

[Taylorbok]

There's a lot of overthinking going on here....

Ya I had a bit of a struggle juggling the measurements, I've got it sorted now. I was focusing on the wrong measurements and was confused about HS of the chamber vs HS on the action.

I think it is better to ask the questions to figure it out and why instead of just following those instructions blindly.

 

[DaveTooley]

Your Counter bore is to deep, that's gonna give you more unsupported case.
BF to nose is .145" and you've already got the .010" clearance built in since you shortened .010 off the whole length.

Agreed
Use the .145" number
Just a note; Your number would not be dangerous and work just fine. Most cartridges have are solid out to about .200".

 

[Dvldawg]

I use a PTG piloted breech cutter, .705 diameter and depth is usually .150 -.155 and I also do .010 clearance.

 

[DR_2297]

I use an 18 mm end mill in a holder in the tailstock to cut the Cbore in Remington barrels with stock extractor and do a final cleanup with boring bar since end mill will have some relief angle from corner to center. Whatever lug to bolt nose distance is, is cbore depth as I set overall tenon length .010 short of lugs. Usually 0.150 - 0.155 in depth.

 

[ELR LVR]

Just a note; Your number would not be dangerous and work just fine. Most cartridges have are solid out to about .200".

THIS ^^^
The extractor groove is an unsupported area anyway.
Plus there is an area of the web which does not expand at all
noted by the pointed out line in the pics
Which the counterbore can also be cut into that area of depth
which conincidentally as Mr. Tooley notes, that line measures right at about .200" from the end.
if the case expands behind that line just in front of the extractor groove... you have bigger problems.
You will notice when FL sizing that short .040" or so area does not get sized back down because it never expands against the chamber wall, which is why there is a noticeable line

 

[Taylorbok]

How far would you expect a bore to "wander" in comparison to the O.D.

I've got a 12" chunk of barrel cut off from a buddy that I threaded for practice.

When I indicated it the bore was .005" out of center from the O.D. is that normal?
This would be in the "middle" part of the barrel, 12" up from where the original chamber would have been.

 

[urbanrifleman]

Remington made about a billion (exaggerating... but not really) Rem 700s with a .155" CB and .010" stick out past the end of the tenon for a total of .165" thou gauge stick out.

 

[swd]

How far would you expect a bore to "wander" in comparison to the O.D.

I've got a 12" chunk of barrel cut off from a buddy that I threaded for practice.

When I indicated it the bore was .005" out of center from the O.D. is that normal?
This would be in the "middle" part of the barrel, 12" up from where the original chamber would have been.

We bought a 34" blank from a small but pretty well known custom maker to cut in half and make 2 custom lever action carbine barrels that had .050" runout in the middle. But I would say on average .001"- 006" with the good customer makers.