.30-06 info

[milboltnut]

Is .004 HS too much in my M70 ? I start with 2.046 and have to size to 2.042. Funny the NG gauge is 2.046 and doesn't come close to the bolt closing and the go gauge is 2.042 which the bolt has very slight resistance on closing.

Is the 06 hard to deal with HS wise ?

[Parashooter]

Quiz -
HeadspaceCquiz.jpg

Answer -
HeadspaceC.jpg

"Is .004 HS too much in my M70 ?" Hard to answer if you really mean "HeadSpace, but .004" end-play is no problem

[bruce]

Ammunition has to be produced to fit the smaller end of commercial chambers. Chambers have to be cut by commercial manufacturers to accommodate rounds within the range of allowable tolerances. No commercial round will give a reliable gauge of head space. Only depend on quality head space gauges for such decisions. If the bolt will close on the go-gauge ... fine! If the bolt will close on the no-go gauge ... not good at all! Remove the rifle from service until a qualified gun smith can correct the head space. Sincerely. bruce.

[milboltnut]

Ammunition has to be produced to fit the smaller end of commercial chambers. Chambers have to be cut by commercial manufacturers to accommodate rounds within the range of allowable tolerances. No commercial round will give a reliable gauge of head space. Only depend on quality head space gauges for such decisions. If the bolt will close on the go-gauge ... fine! If the bolt will close on the no-go gauge ... not good at all! Remove the rifle from service until a qualified gun smith can correct the head space. Sincerely. bruce.

I already know that bro, but thanks!

[milboltnut]

Found this explanation on another forum

On a new chamber the difference between is measured with Go and No Go gauges. The difference between these two gauges is generally accepted to be .004" from min to max.

I measured the high and low step on my case head space gauge and there's .004 difference, big surprise huh !

Also I would say chamber concentric to the bore is important, the case being non-linear shoulder angle can create a problem chamber problem.

[fguffey]

Is .004 HS too much in my M70 ?

No, .004" is not enough but if we are talking about clearance? .004" clearance is perfect. I have a M1917 with a chamber that is long; the chamber is .002" longer than a field reject length gage. That means nothing to most but when I fire a minimum length case in the field gage length +.002" chamber I have .016" clearance. I do not wonder what happened to all of the ammo fired in my rifle before I measured the length of the chamber.

And then I ask about a 30/06 chamber that .011" longer than a go-gage length chamber; is the chamber in my M1917 too long?

F. Guffey

[milboltnut]

Definitely dizzy after your post Guffey. Max SAMMI is 2.058 and minimum is 2.048. Explain clearance verses HS. And did you do a chamber cast to know the length of your 1917 ?

[fguffey]

Milboltnut, forgive, I do not normally check to determine who is active on a thread, hello.

F. Guffey

[milboltnut]

HEADSPACE The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats.


HEAD CLEARANCE The distance between the head of a fully seated cartridge or shell and the face of the breech bolt when the action is in the closed position. Commonly confused with headspace.

How do you know the latter ?

[lyman]

guffey is a bit hard to read and understand sometimes, but once you learn his style, he is usually correct on headspace,

I think he sees it from another angle so to speak,



meanwhile, re the .04

USGI gauges are 1.940, 1.946, and field is 1.950


one a bolt gun, simply measure our fired cases, and throat, and adjust your dies to load to fit,