noob reloader: help me define headspace!

[Hornet_RN]

please help me figure out what they mean on reloading manuals regarding headspace? and why is having the correct headspace important when reloading?

I've tried to look it up in my reading and videos, but i still don't really understand how headspace is defined. all i know is that i shouldn't have too much and that i shouldn't have too little or "BAD" things happen when you fire off a cartridge.

if it helps...i'm primarily reloading .308 Win in a Remington 700, .223 Rem for an AR-15, and .45 ACP for a 1911.

thanks CGers

[buffybuster]

Consider the cartridge case (brass) is the vessel and seal between you and 60,000psi of burning gas. Correct headspace insures the cartridge case is not over stressed and is able to maintain the seal. If the headspace is excessive, then the cartridge case may not be able to make/maintain the seal, resulting in case failure (rupture) and 60,000psi of burn gases going toward your FACE. If headspace is inadequate, you will not be able to close the bolt properly. If you fired the rifle in this condition, it could be a "Out of Battery" discharge meaning the locking lugs were not properly engaged, resulting in case failure (see above).

Headspace is spec'd to with 0.005". It is a VERY CRITICAL measurement. If you're new to reloading, have someone experienced assist/supervise you, read ALL die setup instructions carefully TWICE.

I would start with .45ACP. It's simple to reload and the pressures are lower (20Kpsi).

A simple definition of Headspace: Is the measurement (distance) between the boltface and the headspace datum. This datum varies dependent on the cartridge and where the datum is established. Each cartridge family has it's own headspace specification and gages. Most rimless straightwalled pistol cartridges headspace off the casemouth. Most rimmed cartridges headspace off the rim. Most bottleneck cartridges headspace off the shoulder. Belted (magnum) cartridges originally designed to headspace off the belt, but more and more they are being headspaced off the shoulder like rimless cartridges.

[Chief-7700]

I can only comment on .45ACP don't worry about it I have never trimmed a .45ACP case in 35+ years of reloading. I'm sure that the rifle guys will jump in here soon with good information for you. Please remember that there are no dumb questions about reloading!

[J-cat]

Headspace is the amount of fore-aft wiggle room the round has in the chamber. The more wiggle room, the more the case has to stretch to seal the chamber. The more the case stretches, the weaker it gets because it does not stretch evenly- all the stretching happens at the casehead.

This is why you should adjust your sizing die to bump the shoulder just slightly, about .003-5" at the most. If you bump your shoulder back .010" every time (by screwing your die to touch the shell holder), you will reduce the case life to maybe five loads tops. Sizing minimally will double if not triple your case life.

Straightwalled handgun cartriges are different. They don't stretch so you should adjust your die to touch the shell holder.

[Mrskylinetou]

I don't know if this help u but the max length on an ar is 2.266. Once someone told me this it changed the way I reloaded drastically. Either way I learned just as much as u one this one.

[joedogboy]

A simple way to look at headspace is to consider how much toe room you have in your shoes.

If the shoes are too short for your feet (not enough headspace or too long a cartridge), it will crush your toes and cause you pain.

If the shoes are too long for your feet (too much headspace or too short a cartridge), your feet will slide around and get blisters, causing you pain.

If the shoes are just the right fit for your feet, they will work as designed and you can walk around in them comfortably all day.

Now think of the more technical explanations, with all that gas and pressure, and much more at stake than just uncomfortable toes - don't you want the round to properly fit into the chamber?

For the .45, the overall length of the completed round is important. For the rifle rounds, the overall length, case length, and measurement to the "shoulder" of the case are all important considerations. This is why a straight walled pistol cartridge is a lot easier for a beginning reloader than a necked rifle cartridge.

[bjl333]

A simple way to look at headspace is to consider how much toe room you have in your shoes.

If the shoes are too short for your feet (not enough headspace or too long a cartridge), it will crush your toes and cause you pain.

If the shoes are too long for your feet (too much headspace or too short a cartridge), your feet will slide around and get blisters, causing you pain.

If the shoes are just the right fit for your feet, they will work as designed and you can walk around in them comfortably all day.

Now think of the more technical explanations, with all that gas and pressure, and much more at stake than just uncomfortable toes - don't you want the round to properly fit into the chamber?

For the .45, the overall length of the completed round is important. For the rifle rounds, the overall length, case length, and measurement to the "shoulder" of the case are all important considerations. This is why a straight walled pistol cartridge is a lot easier for a beginning reloader than a necked rifle cartridge.

Very well said !!!

[Mrskylinetou]

I have a question. I'm loading 223 and my case length guage says 1.70 is supose to be my proper length. Do I go off of that and trip to fit or do I need to find a way to measure the chamber? If so what do I need to do that. I have a trimmer but I never used it. I have a case guage (it a price of brass) I'm guessing u use that to compair yr spent brass too?...

[Milsurp Collector]

http://www.surplusrifle.com/shooting/headspace/index.asp

[Boots]

http://www.surplusrifle.com/shooting...pace/index.asp

Great resource!
Bookmarked.

[J-cat]

A simple way to look at headspace is to consider how much toe room you have in your shoes.

If the shoes are too short for your feet (not enough headspace or too long a cartridge), it will crush your toes and cause you pain.

If the shoes are too long for your feet (too much headspace or too short a cartridge), your feet will slide around and get blisters, causing you pain.

If the shoes are just the right fit for your feet, they will work as designed and you can walk around in them comfortably all day.

Best analogy!

[Hornet_RN]

A simple way to look at headspace is to consider how much toe room you have in your shoes.

If the shoes are too short for your feet (not enough headspace or too long a cartridge), it will crush your toes and cause you pain.

If the shoes are too long for your feet (too much headspace or too short a cartridge), your feet will slide around and get blisters, causing you pain.

If the shoes are just the right fit for your feet, they will work as designed and you can walk around in them comfortably all day.

Now think of the more technical explanations, with all that gas and pressure, and much more at stake than just uncomfortable toes - don't you want the round to properly fit into the chamber?

For the .45, the overall length of the completed round is important. For the rifle rounds, the overall length, case length, and measurement to the "shoulder" of the case are all important considerations. This is why a straight walled pistol cartridge is a lot easier for a beginning reloader than a necked rifle cartridge.

thank you for the info...my reloading equipment came in the mail today, this information will help me out!

[joedogboy]

thank you for the info...my reloading equipment came in the mail today, this information will help me out!

You are most welcome. It is a pleasure to help.

One of the worst things about being out of work is that I don't have as many opportunities to use my teaching/training skills.

While there was a lot of great information given in this thread, it was very technical (my eyes may have glazed over as I read it). I hope that my "simple" analogy helps make sense of it.