Setting headspace?

[Rlbol]

This may not be in the correct section but I am not sure the best place to put these questions? So I have a 110 currently in 270 win. I have a 300 win mag heavy barrel for it. So my questions, since the 300 is headspaced from the belted area on the cartridge. Why use a go gauge verses a factory cartridge? Wouldn't all unfired brass be the same if it is in spec? I figured a new unfired peace of brass wouldn't be very different from a go gauge? It would also be easy to measure the belted area? I have never done much with the belted magnums but after looking at the brass and reading about them it seams simpler with the headspace?

I also need a need bolt head. Which size would you use for the 300?
Thanks again for all the great knowledge and advise on this website!

[jonbearman]

I believe the bolt head is .562. You probably could get away with a new cartridge in a pinch,but I wouldnt due to variations in manufacture. I think the gage you want is about 25.00,what is your life worth.

[Dennis]

.532 should be the magnum bolt head.

You can rent go/no go guages, FYI . . . https://www.reamerrentals.com/searchresults.asp?cat=26

You should find what you need in the above link. $5.00 rental + postage - x2 if you rent the no go guage.

It's not to often I need a go/no go guage, but the only one I have never bought is the 338 edge. The rest of them get used, well enough for me to justify buying them. If a set starts collecting dust, you can usually sell them within 5 days on this Forum :rolleyes:


what is your life worth

Something to consider

I converted a 7mm to a 338 Edge, Very accurate rifle by the way. I am glad I use the proper headspace guages. Using 92.5+ grains of powder builds massive pressure in the chamber. I would never second guess this rifle or a 300 Win Mag.

[Rlbol]

Thanks for the help guys

We should get a communal set of gauges. And just let people barrow them and just ship them back.

I will post what gauges I get if someone needs that size.

[stangfish]

The belted magnums are really simple. You set the belt tight to .002 loose. Then neck size or bump the shoulder back .001 or .002. The shoulders vary on reamers by as much as .010. The first firing can be hell on a magnum and the often suffer head seperation. Most guys just keep the shoulder tight after setting the belt(headspace) tight.

http://www.larrywillis.com/headspace.html

[bigedp51]

You do "NOT" want to use a cartridge for a headspace gauge.

Below shows .008 allowable variation in belt length in cartridges case manufacture.

Also chamber headspace can vary .007 thousandths, in a worst case scenario you could have .015 head clearance or air space between the bolt face to the rear of the case. Or if you use a cartridge case as a headspace gauge the next time you buy cases your bolt will not close because the belt is longer on that batch of cases.

http://i122.photobucket.com/albums/o254/bigedp51/300WinMag_zps5ba42e3f.jpg

http://i122.photobucket.com/albums/o254/bigedp51/Headspace_2_lg.jpg
http://i122.photobucket.com/albums/o254/bigedp51/Headspace_1_lg.jpg

[Rlbol]

http://www.larrywillis.com/headspace.html

Thank you, that is a great web site it explained things very well.
So I ordered some gauges I also planned on ordering a new bolt head from ptg but I was unsure of the ejection port? On a normal right hand 111 is the ejection to the right or left? I have never noticed on the regular 10/111 models?