Talk:Headspace (firearms)

message: I changed minimum and maximum to "go" and "no-go". Besides the more common terminology, a gauge made to "maximum" chamber dimensions ought to chamber. A "no-go" is just a bit larger than the maximum chamber dimensions, and represents the smallest size that will not chamber. 66.173.192.96 01:18, 19 December 2005 (UTC)
replies: text: I find this article confusing, even with the diagram (thanks, Xmastree).  Is it possible for a someone with a strong grasp of the topic to go through and totally rewrite it for the layperson?  68.232.64.116 23:23, 12 December 2006 (UTC)

text: Can we get another diagram depicting a cartridge that headspaces on the rim?  I believe there are also come cartridges that headspace on the extractor. SquareWave 02:57, 24 March 2007 (UTC)
replies: text: Headspace is typically either rim thickness (for rimfire like .22 and rimmed centerfire cases like .303), distance from datum line on the shoulder to case head surface (rimless necked cartridges like .30-06), or distance from case mouth to case head surface (rimless straight cartridges like .45 ACP).  If there are any that headspace on the extraction groove, I'm not aware of them.  But I agree that diagrams of these types of headspace dimensions, and some examples of headspace gages, would be very informative.  Lihan161051 (talk) 15:47, 28 July 2009 (UTC)

text: Just reworded the article.  How about it now?  —Thernlund (Talk | Contribs) 01:15, 15 February 2007 (UTC)
thread_title: Go, No-Go

message: The term "Headspace" is used to refer to several things, perhaps we should move the article to "Headspace (firearms)" and make this page a disambiguation link. If nobody objects I will do this in a few days. Sjschen (talk) 05:34, 25 May 2008 (UTC)
thread_title: Move

message: For current or former military calibers, a "field" gauge can also be used.  The "field" gauge is designed to take the place of the "no-go" gauge in military firearms, and functions in the same way.  Military firearms are designed to withstand higher pressures.  As such, a greater tolerance in the firearm's headspace is acceptable, and the "field" gauge takes into account this greater tolerance.  "Field" gauges should be used only on military firearms, and not on commercial firearms.  Headspacing a commercial firearm with a "field" gauge can create an unsafe condition.  (Military arms are not designed for higher pressures than civilian arms.  The Field gauge does not replace the No-Go Gauge.  The No-Go Gauge is used by a manufacturer or gunsmith to tell him he has or has not reached maximum allowable chamber depth and the firearm will be safe to fire.  The Field Gauge indicates if a chamber is under the maximum allowable chamber depth/headspace or exceeds it.  There is a general misunderstanding of this use of No-Go Gauge for reaming new chambers and the Field Gauge for measuring excessive headspace.
Any firearm that locks on a "field" gauge is unsafe to fire, and should be checked by a trained gunsmith.
Guns that fail to lock on the "go" gauge may simply need cleaning, especially at the bolt face, as build-up may occur on this surface and this buildup can cause problems in chambering a round without stressing the brass.
Headspace gauges are designed to indicate simply whether a firearm's chamber is in tolerance. There can be other types of gauges that measure exactly how over or undersize a chamber might be.
:I moved the preceding unreferenced discussion of field gauges out of the article until reference citations may be found to transfer appropriate sections back into the article.Thewellman (talk) 18:54, 12 March 2010 (UTC)
thread_title: Field Gauges

message: It might be helpful also, if go no go gauges were related to threading, as in screws and bolts/nuts.
just a suggestion.
Ghosty1 (talk) 04:59, 15 January 2011 (UTC)
thread_title:  go no go gauge 

message: This article has been expanded by user 123.200.238.50 for clarification and to include additional information.  The additional information requires reference citations.  An alternative definition of headspace is especially confusing in the existing page layout.  I suggest moving the information regarding other chamber dimensions to a new section at the end of this article or possibly to another article (to be identified in the Headspace disambiguation page) to avoid confusion about the single dimension along the bore axis, at a specified radius perpendicular to that axis, fitting the definition of headspace in the cited reference.Thewellman (talk) 07:54, 19 March 2011 (UTC)
replies: text: Reference citations requested above were provided (in non-standard format) by user 121.91.96.140.  Unfortunately, while these references discuss similar subjects, they do not confirm the statements they follow.  I am moving these unreferenced statements to the talk page with a summary of the inconsistencies until more accurate reference citations are provided. I suggest a more informative reference citation format such as:Thewellman (talk) 17:50, 26 April 2011 (UTC)

text: The citation provided refers specifically to Browning machineguns, and makes no mention of being "...the last time you pull a trigger."Thewellman (talk) 17:50, 26 April 2011 (UTC)

text: The citation provided is an advertisement which does not support any definition of free space rather than a single total space of the standard definition.Thewellman (talk) 17:50, 26 April 2011 (UTC)

text: Again, this advertising reference refers only to headspace gauges and says nothing about 'art' and 'science' or the accuracy impairment potential of cartridge misalignment.  The issue of misalignment is more directly related to cartridge diameter rather than headspace.  It may cause confusion in this headspace article and might better be placed in the handloading article.Thewellman (talk) 17:50, 26 April 2011 (UTC)
thread_title:  Reference citations 

message: Have a competent person conduct these checks with the proper gauges prior to using any second-hand firearm for the first time. If you don't, then it may well be the last time you pull a trigger.
Citation:
http://browningmgs.com/Malfunctions.htm
:The citation provided refers specifically to Browning machineguns, and makes no mention of being "...the last time you pull a trigger."Thewellman (talk) 17:50, 26 April 2011 (UTC)
thread_title:  1st unreferenced section 

message: Headspace for a firearm made for rimmed ammunition is the free space that remains between the rim-stop and the bolt face (less the thickness of the rim) once the cartridge is fully within the chamber and the bolt is fully home and locked (if it is a breach locked action).  The purpose of correct headspace is to ensure safe reliable loading and consistent accuracy.
Citation:
http://www.forsterproducts.com/store.asp?pid=24834
:The citation provided is an advertisement which does not support any definition of free space rather than a single total space of the standard definition.Thewellman (talk) 17:50, 26 April 2011 (UTC)
thread_title:  2nd unreferenced section 

message: If the case is too short then the cartridge can move ever so slightly up, down and sideways within the chamber. Imagine the rim-stop has some grit or sand specks fouling the small step at the rear of the chamber. On closing the bolt on a short case, this grit can cause the cartridge to cant in the chamber, putting the point of the projectile off center to the bore. On firing the projectile starts out engaging the rifling with less than optimum attitude, which translates to a broader spread of the points of impact compared to the point of aim. Even when the rim-stop is clean a short-case cartridge with a flush or recessed primer can cant as it is not fully supported at the neck and dips down slightly due to gravity. Target shooters have several ways of eliminating, or at least, greatly reducing these error inducing characteristics. This is the 'art' part of the 'science' of target shooting.
Citation:
http://www.forsterproducts.com/store.asp?pid=24834
:Again, this advertising reference refers only to headspace gauges and says nothing about 'art' and 'science' or the accuracy impairment potential of cartridge misalignment.  The issue of misalignment is more directly related to cartridge diameter rather than headspace.  It may cause confusion in this headspace article and might better be placed in the handloading article.Thewellman (talk) 17:50, 26 April 2011 (UTC)
thread_title:  3rd unreferenced section 

message: I'm curious about the US made version of the Hispano-Suiza HS.404 20mm cannon used during WWII (this is the US copy of the gun the British used in their fighter aircraft). Apparently, the UK-made gun served as an excellent weapon with great reliability, but the US gun never entered wide-spread service due to appalling reliability. The commonly stated reason for this is that the US version, the M2, for some reason was given a longer chamber, which  cause the primers to be lightly struck, not igniting the round. The case appears to be headspaced off the shoulder, as it is rimless and beltless, and has a strong but shallow shoulder. If one were to make a chamber several millimeters too long, so that that the round sits so far into the chamber that the striker can't hit the primer properly, isn't that a headspacing issue? I don't see anything about that on this page, other than that the CIP claims that headspace doesn't need to be tested because "the round will fail to fire" (don't recall if that was from excessive or too little headspacing though). Seems like it could be more clear (both on this page and the HS.404 page). If the headspacing is too LITTLE, the round will protrude  from the chamber and perhaps rupture? How is it that the bolt can even close totally? Would the headspacing have to be REALLY off to prevent that? And too MUCH headspacing leaves the rear of the case unsupported? It says that it can cause the primer to be blown out, or the rear of the case can seperate...wouldn't the case be blown back against the bolt face by the pressure of the explosion? Or does it stick in the chamber due to being forced outwards at high pressure, yet the rear isn't being supported by the bolt face, and so can separate from the rest of the case? Is too MUCH headspace dangerous, or does it just mean the cartridge won't go off? Why didn't the US have problems with 20mm cases bursting if their chamber was "several millimeters" too long? I'm confused as to the dangers and reasons for these dangers, of too much and too little headspacing, respectively..45Colt 19:28, 1 September 2015 (UTC)
replies: text: Your questions about consequences of headspace variation imply your knowledge of the subject may be limited, and cast doubt on the validity of your edits without reference citations. I hope finding the requested reference citations will lead you to the answers to your questions. Thewellman (talk) 04:30, 2 September 2015 (UTC)
thread_title:  20x110mm Hispano cannon, US reliability issues vs headspacing