Can you order a specific headspace length when you re-barrel?

[Taxman1002587]

Can you when you are having new barrel fit to your action request a specific headspace length. For example the SAAMI min/max headspace for a 6mmBR is 1.760/1.770 - so, for example, can you request that the headspace be set at 1.761 still within the SAAMI approved range but at the low end of the range?

If possible would you need to provide your own finishing reamer?

Thanks in advance for your help.

 

[watercam]

Buying and having the smith use your own finish reamer is something I have done with good success. Once had a rifle with problems of brass sticking in the chamber with loads below starting. Ran a new reamer in by hand and problems solved. Any good gunsmith will aim for a minimum sized chamber as you are asking. Just tell him you want it tight (but not under of course).

 

[Taxman1002587]

Thanks for the quick response. I have my own reamer that I purchased from PT&G so I just need to tell the gunsmith I want it headspaced close to the SAAMI min is that correct?

Also do you know if a factory gun is generally headspaced close to the min or close to max - or is there no general rule?

Also do you know of a tool (within a reasonable price range - under $100) to determine the exact headspace - I'm not talking about go/no go guages- prior to firing a new gun?

Thank you

 

[Preacher]

You can have your smith cut the chamber so it will barely close on a Go gauge and it will be on the low side of specs... Most all of Kiffs reamers are on the low side of SAMMI specs ...
Factory rifles are usually on the long side...........

 

[blawton]

What are you trying to really do with this? Do you want this close to another gun or are you worried are new brass not working? Either way you go about it there is a easy fix to headspace issues. Fire the first round out of the brass with the bullets at least .01" into the lands and then when resizing pushing the shoulder back .002" and your good to go. When i did my hunting gun i did it in a 30/338 Lapua IMP. I set the headspace .03" long so i didn't have to trim alot and to shorten the neck on it. Once fired formed it works great!

 

[clowdis]

The most used headspace gauges are nominal (go) to +.004 (no go). I think a field gauge is maybe +.010 so not many gunsmiths use them for chambering. So, getting a chamber to +.001 isn't much of a problem for most smiths, but all BS aside, a tolerance of + or - .001 is reasonable.

 

[Taxman1002587]

Thanks everyone for your help. I now know due to Forum members that new brass is short of the SAAMI headspace min. Some of mine are 2/1000 short. So if the new gun is headspaced close to the max could wind up stretching the brass 9 or 10/1000. I now definitely plan on jammin the first loads when fire forming. I also plan on pulling the ejector pin or button whatever its called out of the bolt face so it is not pushing the cartridge into the chamber - I will put it back in after I get 100 + formed cases - or is pulling the button a waste of time?

Regarding neck tension on the bullet - I am planning on expanding the necks using the Scinclair neck trimmer mandrel not the expander mandrel.
I believe the trimmer mandrel is 1/1000 smaller then the expander mandrel -- will this give sufficent neck tension?

 

[Rustystud]

There are reasons for everything. New comers and folks who really don't know about headspacing should leave those decisions up to a competent smith to give them advise and do their work for them. Experience is a hard but great teacher. There are times for tight headspace and there are times when tight headspace will get you in trouble or killed. Remember the function of the gun is the responsibility of the manufacture or gunsmith. The function of the ammo is the responsibility of the gun owner. All non wildcat chambers should be cut to SAAMI spec. All non wildcat Ammunition should be loaded to SAAMI spec. One can cut a chamber and it will not adjust after being cut. One can adjust ammunition by die forming, fire forming, and trimming.

Too much is printed on the web by folks who don't know what they are talking about. An too much is read by others and taken as gospil.

I chamber a few barrels and build a few rifles. And what is posted by others sometimes scares the hell out of me. Sometimes I scare the hell out of myself.

Shoot Safe

Nat Lambeth

 

[clowdis]

Gotta agree with Nat on this. We sometimes spend way too much time worrying about .001 or .002 when all we need to do is go shoot. A chamber done by a good gunsmith will be within .004 of minimum SAAMI standard and you can shoot any factory brass in it without having to remove ejectors or seat bullets into the lands to prevent excess pressure. In fact you can create excess pressure by seating bullets into the lands rather than jumping them. If you're only .002 under SAAMI minimum on the brass you're good to go.