I need to get a set of gauges to head space a new .308 build but don't know which set to get, I have seen a couple of companies that make them but was wondering if there are differences in quality or if any will work? Thanks for the help.
hiltonjg
Just out of curiosity, I can understand why a gunsmith might need a headspace gauge. But this doesn't seem to be the kind of thing a do-it-yourselfer would need.
Could you enlighten me please?
Could you enlighten me please?
For initial setup of Savage and Rem-age barrel systems, you need to have the correct go/no-go gauge set for that chamber such that you don't blow off your face on the first 3-5 rounds through the barrel.
Indeed, for the more advanced (and lathe-equipped) DIYer, you need the same gauges for traditional shouldered installations as well.
Once you have a fired case or 5 from a given chamber, you can use the casing to RETURN a Savage or other barrel-nutted barrel to it original position...but only with THAT chamber. Any ol' casing cannot be plugged in without risk to one's face.
-Nate
Indeed, for the more advanced (and lathe-equipped) DIYer, you need the same gauges for traditional shouldered installations as well.
Once you have a fired case or 5 from a given chamber, you can use the casing to RETURN a Savage or other barrel-nutted barrel to it original position...but only with THAT chamber. Any ol' casing cannot be plugged in without risk to one's face.
-Nate
The first chamber I ever cut was a .257 Roberts Ackley Improved, and I used a new piece of 257 Roberts brass.
It turns out that is .004" too long.
Ackley chambers need to be .004" shorter so that when the firing pin pushes the case forward, the brass neck base is already pressed into the chamber neck corner.
In belted magnums, I would be foolish to use a SAAMI go gauge. Those should be made at least .005" short per all the brass I have found in 7mmRM, 300WM, and 338WM.
In 7.62x54R I made my own headspace gauge that is one thread long, so I can keep the extractor and extractor relief cut question out of the way.
In the 257 Roberts Ackley Improved Rimmed wildcat I am making right now, I got a lifetime buy of Norma 7x57mm Mauser Rimmed brass, and measured the brass rims. Then the should position will be driven by having the neck lengths come out right.
It turns out that is .004" too long.
Ackley chambers need to be .004" shorter so that when the firing pin pushes the case forward, the brass neck base is already pressed into the chamber neck corner.
In belted magnums, I would be foolish to use a SAAMI go gauge. Those should be made at least .005" short per all the brass I have found in 7mmRM, 300WM, and 338WM.
In 7.62x54R I made my own headspace gauge that is one thread long, so I can keep the extractor and extractor relief cut question out of the way.
In the 257 Roberts Ackley Improved Rimmed wildcat I am making right now, I got a lifetime buy of Norma 7x57mm Mauser Rimmed brass, and measured the brass rims. Then the should position will be driven by having the neck lengths come out right.
I just react to what is available mass produced.
The brass from the factory may have a belt that is .215-", but the same brass is very short at the shoulder.
This means factory ammo in a factory gun has the firing pin push the case more than .005" forward, the belt stops it, the primer goes off and the case expands. The case grabs the wall and then stretches in the rears. The pressure goes away and the case only shrinks .002" The case has been stretched .003" and that is not good. If guy has one rifle and reloads the cases, he bumps back the newly fire formed shoulder .001" or so. The next time that case is fire, much less damage is done.
I reload magnum cases expecting the shoulder to stop the forward firing pin push, just like everyone else.
But when I build a magnum, I headspace the shoulder at .215" to reduce the damage from the first time firing.
The brass from the factory may have a belt that is .215-", but the same brass is very short at the shoulder.
This means factory ammo in a factory gun has the firing pin push the case more than .005" forward, the belt stops it, the primer goes off and the case expands. The case grabs the wall and then stretches in the rears. The pressure goes away and the case only shrinks .002" The case has been stretched .003" and that is not good. If guy has one rifle and reloads the cases, he bumps back the newly fire formed shoulder .001" or so. The next time that case is fire, much less damage is done.
I reload magnum cases expecting the shoulder to stop the forward firing pin push, just like everyone else.
But when I build a magnum, I headspace the shoulder at .215" to reduce the damage from the first time firing.
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