I've never had any (as far as I know) problem with head space but was wondering what kind of guage would be best for setting a die to make sure the head space is correct.

Stoney Point, once again easy to use.

http://www.stoneypoint.com/headspace_index.html

Ol' Joe, have you used it on any belted magnum cases? I was taking a look at it, but it doesn't seem like any of the bushings would be long enough to measure from the belt since, of course, the belted magnums headspace from there, not the shoulder. It almost looks like they just measure from the shoulder for them too. Experience with this?

I checked with Stoney and they didn't have a head space guage for the 7.7 Jap. But they did have a blank that could be drilled for it.

quote:

Originally posted by Blob1:
...what kind of guage would be best for setting a die to make sure the head space is correct.

Actually you don't need anything but your Full Length Resizing Die - set so it Partial-Full Length Resizes(P-FLR). Anything else is a waste of time and effort.

You simply set the FL Die to P-FLR and when the Bolt closes with a slight bit of resistance, you have "Zero Headspace". And you then Set the Die Lock Ring so you can return to this same setting. Of course you need to use the same Shell Holder each time.

If the FL Die is screwed into the press any farther, then you are Full Length Resizing, you have created some Headspace and the Bolt will close as if the Chamber was empty. This needs to be done if you will be hunting in Dangerous Game country so all the cases feed without any resistance.

Since it is "set by Feel", nothing else is needed.
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I know a lot of folks really like the Stoney Point devices, But I'm not a fan. Way too erratic on the readings for me. A long time ago my buddy Don had one. He got five different folks together and let each take a reading. He got five different lengths. Same if one person took multiple readings.

Apparently they do work for other folks real well though, cause I see people recommend them all the time.

Because nothing in this world is perfect, you must take a measurement, turn the case one quarter turn, take another and repeat till you've gone completely around.

Pick one of the measurements or average and then test the other cases. It's fairly consistent but not "perfect"

I doubt that any chamber is perfectly round.

quote:

Originally posted by tmoore4627:
Ol' Joe, have you used it on any belted magnum cases? I was taking a look at it, but it doesn't seem like any of the bushings would be long enough to measure from the belt since, of course, the belted magnums headspace from there, not the shoulder. It almost looks like they just measure from the shoulder for them too. Experience with this?

Tim they do measure from the shoulder only.

The headspace of a bottle neck case will vary from the shoulder blowing out during firing, changing it`s relation tho the chamber. This is normal and it can be controlled by careful sizeing and held to a minimum. The Stoney Point helps in this. A belted case won`t change the location of the belt in relation to the chamber unless you really do something you shouldn`t have . The belt to chamber relation can`t be altered safely, but the shoulder to chamber can.
First, I don`t reload any belted cases so the rest of this is mostly info I`ve gathered from reading and talking to others that do.
The belted case can be sized to headspace off the shoulder in place of the belt and better accuracy is reported along with longer case life. The Stoney Point will aid in setting up your die to do this. ( basicly partial sizeing)Headspacing the belted case off the shoulder in place of the belt will also help prevent early case head seperation due to stretch and should lessen the trimming needed per times fired.

How much P-FL are we talking about? I usually set the die so the press cams over real lightly and it has worked real good. But the way you say is to set it so you have a bit of resitance, just enough to know you have taken up all the space. That is how my cases come out by a slight cam over. A small amount of resistance as the bolt closes.

quote:

How much P-FL are we talking about? I usually set the die so the press cams over real lightly and it has worked real good

I can`t tell you an amount of "cam over" or height off the shell holder to set your die when FL sizing. That`s where the Stoney Point comes to play. I set mine to just touch the shoulder of the case and leave it at the same, or a thousanth under the fireformed measurment when FL sizing. The dies I have normally knock a few thousanths off the shoulder depending on the rifle chamber when set to cam-over.
When I try setting the die a bit high (P-F: sizeing) and not touch the shoulder, the expander will pull the shoulder out some and makes for resistance in chambering as the bolt forces the shoulder back in place. Measuring with the Stoney Point acually will show some growth in the shoulder measurment. I lube case mouths but some drag is still present.which is the reason for the slight set back when I size. The snug fit isn`t a problem at the range but isn`t always wanted when hunting.
When I partial FL size I leave a small ring of unsized case neck (0.010" or so max) this helps aline the case in the chamber IMO but goes let the shoulder move and sooner or later you`ll need to bump it back. For P-FL sizeing I`ve found setting up my die useing a Redding oversize shellholder is the easiest way to go. They come in various heights from 0.001 - 0.010" in 0.002" increments, and just pick the size you need and set the die up as one normally would. Once you figure out how much you need to back the die off this is fastest and of course very repetable.

Well with .375 groups and no problems best let things alone.

quote:

Originally posted by Blob1:
... A small amount of resistance as the bolt closes.

quote:

Originally posted by Blob1:
... Well with .375 groups and no problems best let things alone.

I would say you are doing it correctly. And your groups indicate that as well.

By the way, if you figure out a way to "significantly improve" on those groups, let me know what you did!!!

The idea of headspacing is to be able to have rifles built within certain limits so that when you buy commercial ammo made within their limits it fits yout rifle. When you reload the idea is to ADJUST YOUR DIES SO THAT THE FORMED CASE OR REFORMED CASE JUST NICELY FITS YOUR RIFLE. I think really that was the point that Hot Core was trying to make. If you had a set of 7.7 headspace gages it would mox nix.(meaningless).

Case in point. I, and others I know have bought AB chambered barrels spun them onto Mod. 98 actions and used them just as they arrived. You may have to take a little off your sizing die but that's it. Seldom will these rifles chamber a factory load ; nor were they meant to.Maybe not a purist approach but it gives you another toy to play with. What are you going to use that Arasaka for? It will duplicate .308 performance but with the repeatability you're claiming you may just make a killing at the range. roger