Head space


PDA






jbs606
May 11, 2006, 01:12 AM
Need help. I have been reloading for about one year now for three guns. 308,243,and 30/30. My question is head space. What is this? I have been reloading the same brass for these gun's for this amount of time and have had no problems with head space, I think!! I only neck size my cases except for the 30/30. Is there some way to check my load's to see if the head space is good or not.
Thanks Jbs

If you enjoyed reading about "Head space" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
The Bushmaster
May 11, 2006, 01:40 AM
I don't know about the other two, but if the .30-30 has too much head spacing the fired case will show a primer backed out just a little. If it isn't...No problem. If it is backed out a bit I have the solution to solve it.

ClarkEMyers
May 11, 2006, 02:17 AM
Wilson gages do a good job of gaging cases. RCBS sells a case mic and others also sell tools.

Notice that headspace although strictly defined in SAAMI terms for each cartridge becomes a little fuzzy for the reloader. Best to read a book or do a search and read at some length.

The .30-30 by definition headspaces on the rim which can gradually pick up burrs and such but is mostly unchanged by the sizing die. Just the same setting back the shoulder of any bottlenecked case should be avoided.

Compare the head to shoulder on a new case, on a fired case and on your reloaded case. Any difference should fall within narrow tolerances that vary with different circumstances. Taking a more obvious case :D for example once fired 7.62X51 brass which has been fired in automatic weapons is often sold for use as .308 with the caution that small base dies should be used to first resize. The machine gun chamber is usually considered to be somewhat different from the commercial .308 rifle chamber. Similar differences are found in other firearms including firearms with more or less stretch. Rear locking actions often stretch more on firing than front locking actions so that the case also lengthens to match the stretched chamber, then the chamber shortens up again so the case can be too long for the cold chamber. Most cases if fired and resized enough will eventually lengthen not only at the neck but at the shoulder - that's why rifle cases eventually need trimming and having the shoulder set - bumped - back - see e.g. Redfield die sets with both a necksizing die and a shoulder bump die. Most handgun cases start out short and never grow over long. Notice that any brass trimmed from a rifle case has to come from someplace and the case may have lost enough brass to be too thin while still looking good.

Many people find that modern quality control of firearms, brass and dies means that they never have to worry about such things and just keep shooting, reloading and shooting some more. I always use Wilson gages or equivalent and I have had only one rifle out of many where headspace became a real issue - a factory .30-'06 chamber that was way too long and cases stretched and would have separated if resized and reused. That one was pretty obvious.

Ol` Joe
May 11, 2006, 02:25 AM
Headspace with RIMLESS bottle neck cartridges is the distance between the bolt face and a datum on the shoulder area of the chamber. The fact you are only neck sizeing and not touching the case shoulder when sizeing means you have a fireformed case that SHOULD fill that space as perfectly as it gets. With the 30-30 and other RIMMED rifle cases headspace is the area between the bolt face and the back of the chamber that the front of the case rim rests on when chambered.
The best way to size any case for your chamber is to do it the least amount that allows the cartridge to chamber easily in the firearm. Don`t move the shoulder unless chambering becomes difficult and then only enough to cure the problem.

The Bushmaster
May 11, 2006, 11:29 AM
The trick that I have for the .30-30 was told to me by a prominant gun smith that made the top NRA 100 when the NRA was making that list. It is for old Winchester mod 94's that have a little wear on them. Just like a lot of us old codgers...He did tell me that it was only to be used on those lever action rifles that use rimmed cases.

Smokey Joe
May 11, 2006, 01:22 PM
Jbs--Headspace has been defined for you so I won't repeat that.

You are FL sizing the .30-30 cases as you should--that won't change the headspace, and your NOT reporting that the cases are stretching and cracking after 3-4 firings/reloadings tells me that yr .30-30 has a chamber that is not worn oversize.

You are neck-sizing your bottleneck rimless cases, which tells me that they are correctly headspaced for your rifles after the first firing.

All your cases chamber in your rifles with no difficulties.

You don't have a problem, mister!

Now, you may develop a problem down the road, if your cases start chambering hard. The solution is a special shoulder-bump die, which pushes the shoulder of the case back just a tad without changing any other case dimensions. Worry about it if/when it happens.

Enjoy!

jbs606
May 11, 2006, 06:18 PM
Thanks to all for the reply, big help.
JBS

Sunray
May 13, 2006, 01:49 PM
"...What is this?..." Headspace is a manufacturing tolerance thing for the rifle. It allows for slightly different sized cartridges made by all ammo manufacturers to be fired, safely, in the rifle. The case and loaded ammo, themselves, have nothing to do with it. Neither have headspace, only the rifle has headspace. Nor can bad headspace be fixed by doing anything to the case.

The Bushmaster
May 13, 2006, 01:58 PM
Sunray...You're right, of course. But...................:D

ClarkEMyers
May 13, 2006, 05:19 PM
IMNSHO - there are circumstances in which the chamber is too long, a condition of excessive headspace - and by fireforming the case to fit the chamber that is doing something to the case - cases can be made to fit the particular rifle.

This is often accomplished by seating bullets out so the case in effect headspaces on the bullet into the throat/lands. The case is fireformed with light loads. In this circumstance a normal case and bullet combination would likely stretch and so weaken the case. With the bullet seated out the shoulder is blown forward to fit the long chamber.

After fireforming proceed as usual but of course segregate the cases for use in the particular rifle. This is one of the many uses of the Wilson adjustble case gage - belted (and rimmed) cases are more likely to be used in firearms with long chambers because the chamber can be long but the headspace on the belt correct.

This might be thought of as creating a custom wildcat - a variation on an improved cartridge - and of course does nothing to correct headspace on the firearm in the sense of making the headspace correct by SAAMI specification for the named cartridge - that does require machine work - typically setting back the barrel or rebarreling or in a few cases e.g. some machine guns some other action.

The Bushmaster
May 13, 2006, 06:40 PM
Aah...I believe ClarkEMyrers has hit on what I do to keep the primers from backing out in that ol' Winchester Thutty-Thutty. I set my resizing die .030 from the shell holder and fire form the case. It tends to move the shoulder forward setting the case head against the bolt face. And you are right. My rounds will not chamber in my son's newer Winchester mod 94.:) But the primers don't back out anymore.

brickeyee
May 13, 2006, 07:18 PM
"Nor can bad headspace be fixed by doing anything to the case."

Not true. You just create brass for the chamber you have and treat the gun as a wildcat.
As noted above, pretty easy. Though using a bullet to fire form is not very reliable. Expanding the neck and then creating a false shoulder is safer and produces better brass with less chance of any stretching.

If you enjoyed reading about "Head space" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!