Ask Ian: What is Headspace? (And Why It Matters)

From LongBeef on Patreon:
"What exactly is headspace? And how important is headspace in old milsurp guns vs. more modern guns?"

Headspace is basically the amount of play a cartridge has in a chamber. There has to be some to account for manufacturing variations in guns and ammunition, but too much or too little can cause problems. Too little can cause extraction problems and poor accuracy. Too much can cause poor accuracy as well, and also shoulder separations, case head separations, and kabooms.

Also shown in this video:

[BigBadBalrog]

It always surprises me when Ian explains the topic in the first 30 seconds, but then continues to give us a stream of useful info for the next 10 minutes plus

[marknovak]

The thickness of a sheet of paper is the difference between too short and too long. Well said sir.

[robinblackmoor]

If Firearms 101 was a college class, Ian would be the professor that everybody on campus wants to get.

[waylonsmythers]

Overlaying a physical bullet onto a diagram, while explaining different processes & issues, really helps to understand them better. Please do some more like this in the future.

[Niinsa]

I'm a technical illustrator, have been for twenty years. Your illustration of headspace is top notch. In my defense, I often have to illustrate something explained to me by someone who is not good at explaining. You obviously know what you're talking about, and you're good at explaining. Those two don't always go hand in hand.

[MrMaselko]

Videos with Ian explaining these kinds of topics are great

[cameronfelkel]

Ian hit it on the "head" with this answer! I work at FN America in Columbia SC as a barrel QA technician in the barrel shop. This is exactly what headspace is and the importance of it being correct. If you have the experience and means to get the gages to check it, do it. If not please don't try. Excellent video on this topic Ian!

[DANO-]

Ah, headspace and timing! Essential Marine Corps training for the Ma Duece 50 cal. Brings back fond memories .

[thegreenman]

I’ve known and been checking headspace on various rifle platforms for years now, that being said this was extremely informative and easy to understand for those who didn’t know or understand it.

[WingZeroGWO]

I'd just like to point out that there are situations where a headspace issue is less obvious, meaning that the weapon can appear to be cycling fine for several hundred or thousands of rounds, and then suddenly detonate. Typically what happens is a minor case of the situation you were describing @4:50 but instead of the spent case producing an evident indication, what happens is the locking lugs become fatigued from repeated impact of slamming that short distance, until either the bolt lugs shear or the trunnion lugs shear.

[kjn]

Class is in session. Professor Gun Jesus teaches more about head space in 10 minutes using hand drawn diagrams with an actual cartridge overlay than probably 90+% of us knew from years of being pew-thusiasts. Yet another reason to live this channel.
Thanks Ian. Merry Christmas! May all of your head spaces be just right, your Scotch be a fine single malt and your shots be inside the 10 ring.

[grizzlyblackpowder]

Should have answered this the way my drill sergeant did for a private in my basic training: "headspace is the thing that stops your face from getting blown off, private".

[spondulixtanstaafl]

Headspacing is one of those firearms concepts that can be tricky to understand, thanks for a thorough and concise explanation . I never tire of content like this.

[SamGray]

I had an SMLE with blown out headspace, so, of course, it was non-firing and used as a wall hanger. A certain thief stole it, along with other items, and the police were unable to find said thief. I often wondered if they ever tried to fire it.

[boingkster]

It's really important if you want to have a properly functioning, safe and accurate firearm. If you have too loose a tolerance you will find that the brass backs out of the chamber under pressure and ruptures at the case head (bottom of the brass) which vents hot gas at the shooter, or has too large a gap to jump the projectile to the rifling which causes accuracy issues, among others.

I've experienced both but never severely. I've also seen a few Lee Enfield conversions which had such severe headspace issues they ruptured every case they fired just above the case head.

I immediately told that shooter the short explanation and that he really should take it to a gunsmith to fix.

I never saw him again but I hope he listened.

Awesome work on the video, Ian, and a really good illustration on what the problem is and how to identify it! As always, keep up the good stuff.

[iainbaker]

It’s easy to forget until you see a video like this just how ingenious a design a modern firearm is. Probably why the design hasn’t really changed much in the last 100 plus years - it’s hard to improve on such a fundamentally sound design.

[Peter-uryy]

These videos are arguably my favourite. Helps you to understand a lot more of what the weapon rundown videos are actually talking about.

[petervienna]

Very very good video!

When I bought my (brand new) AK here in Austria a few months ago - having no previous practical experience with guns - the guys in the gun shop DID NOT KNOW THE TERM HEADSPACE ! When I told them that I heard a lot about headspacing on videos of Brandon Herrera and other people, they said something like Headspacing would surely only be some problem of the americans and that they don't have that kind of issues with their guns in the shop...

Later I found out that they primarily sell AR-style Rifles and only the expensive kind, they don't really build guns themselves (only minor repairs and stuff like that). So they might never have had issues with improper headspacing (of course they only use best-of-the-best ammo, too).

But still, this should have been a major NO-GO for me. Now I know better and with Ians excellent explanation, I know why it is really important.

[dalevines]

I used to run the calibration lab on the USS Carl Vinson. We calibrated everything. From headspace gauges to rubidium oscillators. Oscilloscopes, spectrum analyzers. It was good.

[andrewnovak]

Thanks! Always enjoy your videos. I particularly appreciated this one.