All you millennials complaining about his not buying a whiteboard or paper are missing the bigger picture. The skilled English and German craftsman who built or build high end museum quality guns, built their own tools. In fact, as an apprentice, you didn't touch a gun until you could make the screws or fine tools to build said guns. Mark is a Craftsman of the old school quality. Did you not notice the adjustable length white board he made from a common piece of paper towel? You don't need to buy frivolities when you have the skill to do it yourself. Mark is the man!
The biggest revelation for me, back as an engineering student was "nothing is ever perfectly made to dimension". This leads to "everything is made differently", "everything has primary and secondary dimensions", and "everything must be measured". One of the purest illustrations of this is headspace. However a gun headspaces, tells you the datum.
The other thing that most people don't seem to appreciate is that most of the normal reality around us is good to 2 or 3 decimal places at most. Vast quantities of reality are constant to about 3%, which is like 2 1/2 decimal places, not the 8 to 12 people are used to getting from a phone or pocket calculator. People somehow think that more decimal places is more accurate, but really in most cases it is just more meaningless.
@@lwilton I can agree with you to a degree. The Decimal place has been a Standard for the growth of the Industrial revolution. 1 Decimal place is Sloppy and requires true hand fitting. 2 Decimal places allowed for manufacture of rifles that had 'basic interchangeability' meaning that the lock, stock and barrel of two (or more) rifles could be swapped around. The Third Decimal place, the Thousandths of the inch was the big game changer. The .001 allows for relatively interchangeability of machined parts. Gears in a manual transmission and a lot of gun parts. The third Decimal place still required some hand fitting of extremely intricate parts (the hammer and sear are a good example). On a 1911, you can replace the hammer and it may (or may not) function without fitting. The 4 Decimal place is an interesting place. If something is 'blueprinted' to the 4th decimal,, that allows for nearly true interchangeability (think swapping AR hammers and triggers without any fitting). Now we reach the BIG Problem, consistency... Parts (or cartridge cases) are going to have some variations. Also, there is accumulation of undesired 'material'. That undesired material can be dirt, fouling or anything that didn't belong in the dimensions. That's why I agree with you. As far as a machine goes, planning the design to the 5th Decimal or beyond is counter productive because your designing for failure. Whether it is manufacturing tolerances or undesired material (that everything in the world has) getting in it, the machine or system will fail to function correctly. Hopefully this will make some of those .00001 people understand that accuracy to that level is theory and Not a workable thing! Ya'll Take Care and be safe, John Just a side note... Did you know that in the past in England, that they had an 'Enfield Inch'?? Talk about trying to 'Monkey-Wrench' something, those Brits made a specific unit of measurement different, but only for weapons of the Enfield facility... Dang Guys, You're killing me over here!🤣🤣🤣
@@JohnDoe-pv2iu Actually I did know about the Enfield inch. I think there was an interesting story around it's creation, but I've forgotten it long ago.
Brings back the time I really got some dude mad at me. I called him for bullshit on making a zip gun for a 9mm in jail. I asked him how he headspaced it. He couldn't understand that if he put a rimless cartridge in a tube it'd just slide out the other end. I've seen some brilliant engineering by cons but cutting a chamber in a tube sans lathe or reamer of some kind is beyond believe. More so from someone who had no idea what headspace meant. Thanks again sir. Never get tired of your content.
The amount of knowledge being shared on this channel is impressive and I appreciate very much that you're sharing it with us, what you're talking about is a perishable skill and even if I'm not a gunsmith nor skilled enough or equipped enough to emulate what you're showing, it matters a lot.
Great video Mark, I learned about headspacing in depth, while reloading 40-72 ammunition for my dad's (formerly my Grandfather's) 1892 Winchester lever action. I'd done basic semi-auto (9×19 paraballum, .45ACP, .380ACP, 9X18 Makarov). Was a learning curve finding the right powder to not overpressure the cartridge, or barrel, but I have a formula in my "reload notebook" for what works. (Lyman's 40-70 data was close, but I made a few fine adjustments).
I've always had trouble wrapping my head around headspace - you've done a fantastic job explaining something I've long been curious about. Thank you so much for taking the time to make this video!
Mark I am sure someone else called it but...the Roth Krnka or Roth-Steyr as it is called in all the books (I know, designed by Karl Krnka) is NOT chambered in 9X23 Steyr but rather the 8mm Roth-Steyr. Ballisticaly a little like the 32ACP. 20 to 30 years back Fiocci made this one and I bought 2 boxes I cherish.
PS: the 9X23 Steyr was used in the 1912 Steyr Hahn the Army pistol of the Austro-Hungarian Empire. the 9X23 is ALMOST identical to the 9mm Bergman Bayard or Largo but slightly more tapered. I have 2 Steyr Hahns. One is a bit more sloppy and will chamber 9 Largo, the other will not. The Roth-Krinka /Steyr was from 1907 and was the issue pistol of their cavalry. Ian Mcollum did a wonderful video witha older gentleman on this pistol some years back. And yes, I have one.
When Dad gave me his hand built .22-250 it came with instructions ... always shoot fireformed handloads from this rifle. It was built when .22-250 was still a wildcat cartridge and the headspace is .0035 - .0040 long at the shoulder from what became the standard. With factory rounds, it shoots like crap. However, with fireformed brass in a mid-range handload, its performance is EPIC. BTW - most of the brass I got from him is actually headstamped either 250 SAV or 30-06.
@@ndenise3460 I actually have the reamer and dies that were used/made when the rifle was built. There are about six of them to gradually bring different cartridges to size as well as a dedicated neck sizing die (which is the one I use the most.) I just have to be ultra careful because I truly have a one-of-a-kind.
beautifully explained.... thank you for sharing the info about the 455 Webley 1911... I didnt know theyd chambered it in that before... wow... thank you Mark... as for the 45-110... i'm a fan... I own a sharps chambered in it... fun gun to shoot
Love seeing 1911’s on the bench. Takes me back to my childhood watching a gunsmith back in the day put a comp on one (when that was the cool new thing). Love seeing a master at work! 👏🏼
Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) defines headspace as: "The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats. 1. BELT: A type of chamber design in which the cartridge seats in the chamber on an enlarged band ahead of the extractor groove of the cartridge body. 2. MOUTH: A type of chamber design in which the cartridge seats in the chamber on the mouth of the cartridge case. 3. RIMLESS: A type of chamber design in which the cartridge seats in the chamber on the shoulder of the cartridge case. 4. RIMMED: A type of chamber design in which the cartridge seats in the chamber on the rim or flange of the cartridge case."
Just, the amount of knowledge, Mark has. It’s just a sit back and enjoy the master at work. I have learned a lot. Keep up the great videos and information.
unrelated, but can you please explain how you make a card scraper cut on the push and on the pull stroke? I know hor a normal hook works, just the push thing is new for me
Not sure if this would help but here's a tutorial by Mark on how to make and use a card scraper. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-7NLQEmwAvo4.html
Bought a spanish mauser recently and the term headspace came up in the conversations. had an idea what it meant but this video helped solidify the concept Thanks
Thanks Mark, I understood what headspace is but it's always better to hear it again and get reedgimacated! Also clearing my head space is worth the time watching your educational videos!
OK, I'm definitely not a big 1911 guy - but that 455 Webley 1911 has gotta be one of the coolest things out there!!! A real "who the hell thought that would be a good idea?", but an idea that I'm glad exists!
One I've always wondered about is headspace on a Oerlikon 20 mm cannon, because it's blowback but also advanced primer ignition... So the bolt is still moving forwards into the chamber when the round fires. I suspect it's one of the few guns that doesn't really have headspace, but I've never had the chance to talk to someone who was trained on one.
The Oerlikon has a rebated rim which is narrower than the diameter of the case. The extractor grabs the rim and holds the case hard against the bolt face as it goes up the chamber. The chamber has an extension shroud which completely encloses the bolt and round. For a full explanation, look in George Chinn's book on The Machine Gun.. vol 4. You can find it on the internet..
I'm aware of how it operates, but my point was there isn't a defined area of the chamber where the cartridge case stops with the bolt fully pressed up against it... the bolt is still moving forward further into the chamber as it fires and only comes to a stop very briefly before moving backwards and extracting (and the point at which it does so varies). How would you define headspace in such a design? it doesn't really have one as far as I can tell.
@@etelmo I suppose, using Mark's view that an unlocked breech has no headspace, you are correct. At the end of the day, we are discussing the tolerances that apply to a closed, static breech to ensure that the round can achieve battery. The Oerlikon never achieved battery in the conventional sense, and (..as I recall) the round is fired when the breech block engages a fixed pawl in the reciever, operating the striker.
@@felixthecat265 IIRC there were two blocks on the exterior side of the chamber that actually locked the gun…it’s been a loooong time since I worked on one (we had them in the USCG when I was in..1990 ish) and we had to use a feeler gage to check those were within tolerance (headspace)…
Good stuff, good stuff. I think you might want to add how having too much headspace in locked breech guns, especially rifles, can lead to casehead separation and tie this in with an understanding of GO/NO-GO/FIELD gauges.
At approximately time hack 4:00 you imply that the "abutment space" is the headspace. I respectfully disagree. Headspace is the distance measured from the bolt face to the portion of the chamber restricting the cartridge from further forward movement.
As a gunsmith myself from 1985..on I enjoy seeing you from Charleston..I'm in Sumter sc..heard of you for years..always wanted to meet you but ..I don't drive long distances .hay I'm 71....only got one eye now so night driving..gone..o well...
@Mark Novak Starline brass has 9mm styer and #4600 - 9x23 Comp Brass (Small Rifle or Small Pistol primer). Dunno if that may help you and the owner or not.
Ahhh.. the abutment on the Martini is the back of the hinge groove.. the pin takes NO firing stress.. a brass pin works fine, as would a wood one, although it would wear a bit! It is perfectly safe to shoot a Martini with no pin fitted, although the bolt might pop out when you open it! Peabody got it right with the design of that breech block... strong as hell!
This is excellent mark👍. I think however rimfire deserves some elaboration and explanation in a separate video as it does not really fall into any of these categories neatly as a rimmed cartridge. Headspace on a rimfire is even more critical than on center fire not only for accuracy considerations but for safety reasons. Ever had a semi-auto rimfire go full auto due to slam firing? I learned this lesson on a couple rimfire projects years ago😂
Wait.....for the (presumably) Colt Woodsman 22.....you say the headspace is zero. Hmmm....isn't there a depression ( like all 22LR's), in the forward surface of the slide, with remaining metal that "surrounds" the rim of the 22 cartridge? The depressed front surface of the slide, is where the firing pin hole is...and isn't that depression a "smidge" deeper ( as measured from the surrounding surface plane of the front of the slide), than the rim thickness of the cartridge? Headspace for this 22 would then be the rimfire cartridge spec rim thickness ( typ 0.040") "plus" the rattle-gap....say, another 0.002" to 0.003"...right?...to yield a headspace value of maybe 0.043" or so....not zero. Said another way, it would be the depression depth total. The metal of the slide that "surrounds" the depression is what hits the back of the chamber (breech face) to limit forward slide travel....so THAT interface is zero gap, leaving the depressed portion as the headspace dimension, I would think.
There has to be some relief made to prevent the rim from being crushed in a semiauto .22 rimfire. A sharp blow to the rim, even if spread out over the entire surface would have the potential to ignite the priming disc in the base of the rimfire cartridge resulting in an accidental discharge. Also critical is firing pin protrusion that it does not hit the edge of the chamber, but yet is still long enough to point crush the rim.
@@TheWilferch When ever I chamber a round in a 22 rf, especially a semiauto one, I am always conscious that while extremely rare, that act could be enough to cause a discharge. Just takes a speck of debris or out of dimension rim along with a super sensitive priming issue to have a discharge.
@@loquat44-40 ..I get that....with a semi-auto pistol ( as example), locked back and the slide then released ( also picking up a round from the mag).....the speed at which the slide slams forward *can* discharge a round... if the rim is too thick ... or there is debris in the rim-recess of the front face of the slide....cheers.
in short, a tolerance inside the breech for brass cartridges(which also impossible to be 100% the same all the time, hence, machine tolerance)? too loose and the cartridge ruptures inside breech, hangfire etc., too tight and the cartridge shears/fail to eject, or even dangerously firing in what seem to be in-battery position.
Good one Mark, now that all the customers are totally confused except for the rare exception.......LOL.....lets really throw em in a titheee and discuss lands n grooves and rates of twist and stabilization/ bullet weight/shape and dont forget to throw in bullet ogive vs COAL.......
Does .32 ACP not headspace off the rim though. I thought that was why Browning went with a semi-rimmed cartridge over a true rimless for that and the 9mm Browning Long.
Yes .25, .32, .38 ACP ( .38 Super) are semi-rimmed and originally used the rim to headspace, while .380 ACP and 9mm Lugar are rimless and headspace on the neck. However many manufacturers later made guns which headspace on neck of semi rimmed cartridges.
Great explanation for the guns you went over. The only issue I have is the 22 Rim Fire. It depends on the gun not the case. Some rifles have a recess in the barrel like most rimmed cartridges and of course the model you showed and I presume others do not. Thanks for sharing.
I would argue that, recessed or not, the controlled depth the 22LR cartridge stops is dictated by the rim on the case itself. If a chamber is not recessed the bolt face would be to accept the base/rim of the cartridge, headspace or depth of the cartridge in that chamber is controlled by the rim. On a chamber that is recessed the bolt face would be flat to close the action, but the depth of the cartridge in the chamber is still controlled by the rim. The other way to think about this is putting a screw into wood, where the head of the screw is the "rim" A countersunk screw head sits below the surface of the wood, to put something on top it can be flat. This is your recessed chamber with a flat bolt face. A screw that isn't countersunk sits above the wood, in order to place something on top of it and to sit flat you need to hollow out a spot for the screw head in what you are placing on top. This is your recessed bolt face/flush chamber. I'm not sure if I cleared anything up but I hope so
@@endutubecensorship In the case of the hand gun in the video, it had neither a recess in the bolt nor the barrel and was claimed to have zero headspace. Therefore, just doing the math, if there is a recess in either the bolt or the barrel the headspace must be greater than zero. The amount is controlled by the thickness of the rim and allowance.
Case length is checked on a rimless shouldered rifle cartridge because if the case mouth comes into contact with the lead in the chamber it will crimp the case mouth into the bullet causing excessive pressure as the friction to move the bullet will be greatly increased, too long of case may even prevent chambering as the case mouth will ram into the lead in the chamber.
A lot of references define the headspace as the distance from the datum to the breech face. Is the abutment distance the same thing?? (ie your first sketch??) SAAMI = "The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats." So it is the distance from breech face to face of the cartridge. Not a challenge as I will nevr catch your genius on all this. Just confused a bit between what you called abutment distance and headspace distance.
It’s not. SAAMI specs show a “headspace dimension” between the breech face and *something*. For a rimless bottleneck cartridge the something is the datum line on the shoulder. For 45 ACP it’s the case mouth. For rimfire it’s the forward edge of the rim, and for belted cartridges it’s the forward edge of the belt. The abutment can be important for firearms where there could be significant variances in the distance between the abutment and the breech face. An M1 Garrand or it’s cousin the M14/M1A come to mind immediately. You should not take a bolt out of one Garrand and drop it into another without testing headspace, and don’t be surprised if the end result fails headspace tests. There’s too much inconsistency in manufacturing and the shape of the locking lugs makes the problem worse. In contrast, the abutment in an AR-15 is an integral part of the barrel assembly. It’s relatively easy to manufacture the necessary parts so that you can swap bolts between barrels. You still should check headspace every time, but it’s unlikely to be off by a significant enough distance.
@@chipsterb4946 The TM doesn’t recommend swapping of bolts in a M16 (AR15). It can be done due to tighter manufacturing and tolerances nowadays. But it’s not recommended due to wear.
@@mikeseigel6566 I didn’t express myself well at all. I recently had a “match” AR-10 barrel that did not have enough headspace to close on a 308 Winchester GO gauge. Same bolt was fine in a different barrel. Fortunately I have the gauges and the barrel maker reamed another thousandth or so out of the chamber and all was good. TL:DR Mike is correct that you shouldn’t assume AR-style bolts are interchangeable. The point I was trying to make is that headspace often gets adjusted when *building* a Garrand or M-14 style rifle. It’s quite rare to have a problem when building ARs but it does happen.
@@mikeseigel6566 Interesting enough, The Canadian Army Operates with bolts being completely interchangeable in the C7/C8 (M16/M4) and C9 (M249) Fleet. For the C7/C8 Armourers will verify all bolts on a interchangeability gauge anytime we work on one. no such gauge for the C9 However.
For a rimmed cartridge without straight sidewalls, like the 11mm Gras for example, do you ever have issues where the rim and shoulder of the case "disagree"?
Actually, does the same issue come up for the belted and bottlenecked cases that seat on the belt instead of the shoulder of the case? Asking for a friend 😀
pretty much what hold the line said, the automatic natures dependent on the fireing mechanisms setup. im not sure how much detail your looking for but forgotten weapons, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Ga4uoWmfEt4.html, has a nice play list of different locking mechanisms with fire arms examples. other videos outside of that playlist have more teardown of these mechanisms
A firearm designed for automatic fire will often have less rotational travel to lock the bolt. Think of the huge amount of arc on a bolt action rifle vs the tiny arc angle of AR bolt lugs. Then there are open bolt designs.
So wait... On that first gun you show.. the martini Henry 22 The headspace... Would be something like.. damn near 3 INCHES.. Is that what I'm getting here.??? According to 2hat was just write down that should be right
That is what he’s explaining. As long as the breech block or whatever it’s called on a martini is in spec then the measurement from that pivot pin to the edge of the barrel will be a fixed dimension and that is the headspace. I think generally people think of the headspace as the measurement of the gap between the cartridge case and the bolt face. Really that measurement is a result of the actual mechanical headspace measurement he’s explaining. From the datum line to the abutment. And hinges on tolerances like the locking lugs being in the right place, lugs being the right length, the bolt being the right length, etc. If you put a no go gauge in a gun and it closes on it all that tells you is that it’s outside of factory headspace. The gauge doesn’t tell you why it’s outside of headspace. What Mark is explaining shows you what the actual locking surface is in relation to the chamber and how the different cartridges are held in relation to that surface. This video gives you the mental tools to actually look at the firearm and determine what is causing the gun to be out of headspace and/or understanding how to set headspace on a new gun. This video is the what and why part of the equation.
