trouble closing bolt on a round (detailed and long post)

[soylentblue]

Not all gunsmiths are the same - in my experience, 4 out of 5 that call themselves 'gunsmiths' don't know much beyond how to assemble the parts of an AR.
The most important thing for them to know is that they sometimes they don't know.

[WeldonHunter]

Not all gunsmiths are the same - in my experience, 4 out of 5 that call themselves 'gunsmiths' don't know much beyond how to assemble the parts of an AR.
The most important thing for them to know is that they sometimes they don't know.

Yeah I can understand that. I've been an auto tech for 32 years and an ASE Master Certified most of that time and he seen all kinds of self described "mechanics" over the years. One thing I used to tell my customers is if they ever talk to a mechanic that says he knows it all....run as fast as you can. Working on machinery, especially automobiles is a dynamic process as far as methods go. I used to teach all my apprentices that no matter how long you've been doing something always be open to learning new methods.

[wingspar]

Bold head. $25. https://www.libertytreecollectors.com/p ... category=0

Okie No-Go_Gauge. $25. http://www.okiegauges.com/sales.html

[steveholt]

wouldn't it be best to purchase all 3 gauges? in case there is too little headspace and the GO gauge doesn't close and in case there is too much headspace and it closes all the way up to a field gauge?

so let's say i pass the no go gauge and the bolt doesn't close all the way, is there a chance that it might not close on a GO if there is too little headspace? or generally if the no go is a pass then the go gauge should be a pass too? how likely is it that a bolt head passes a no go but fails the go?

adding to that, if it does close on a no go gauge is there a possibility it closes on a field gauge rendering my headspace too excessive and unsafe?

am i overthinking safety or with mosin bolt heads and mosins in general are the odds typically in my favor? how likely is it for unsafe headspacing on mosins?

[graphic914]

I am having the same problem, think i will go the new bolt head way, cant go wrong for $25

[WeldonHunter]

wouldn't it be best to purchase all 3 gauges? in case there is too little headspace and the GO gauge doesn't close and in case there is too much headspace and it closes all the way up to a field gauge?

so let's say i pass the no go gauge and the bolt doesn't close all the way, is there a chance that it might not close on a GO if there is too little headspace? or generally if the no go is a pass then the go gauge should be a pass too? how likely is it that a bolt head passes a no go but fails the go?

adding to that, if it does close on a no go gauge is there a possibility it closes on a field gauge rendering my headspace too excessive and unsafe?

am i overthinking safety or with mosin bolt heads and mosins in general are the odds typically in my favor? how likely is it for unsafe headspacing on mosins?

Steve you can never over think safety. Headspace gauges check a critical clearance and there's no substitute for checking it. No one can tell you what your odds are of it being correct because it either is right or it's not. Measuring things is how you eliminate a potential problem and there's no substitute for this. I never did a brake job on someones car and guessed if the rotors or drums were still in specification. I measured them and checked that against the recommended specs. To do otherwise was to take their life in my hands. Something I'm not willing to do. We wouldn't have recommended checking it if it wasn't important. Anyone who comes in here and recommends otherwise is being casual with your safety. This is a firearm we're taking about that is basically a controlled explosion inches from your face not the spark plug gap on a lawnmower. It has the potential to kill you if something isn't right. Any checks that can be done to minimize the possibility of failure are always a good thing.

As for the gauges, I have all three but the ones you'll need for the most part are the Field and No-Go. At a minimum the Field gauge will be ok. The Go gauge is mostly for checking a new rifle or one that the barrel was replaced on to set minimum headspace and it's unlikely you'd ever need it. The Field gauge checks maximum/excessive headspace and was as the name explains for use in the field to check rifles for safe use. The No-Go is less forgiving but if it fails the No-Go but passes the Field gauge the rifle can still be fired but is getting to a point where the headspace needs to be addressed some time soon. This is from Okie's site.

"Headspace is measured in different ways on different calibers. For a rimmed cartridge such as the 7.62x54R (where R stands for “rimmed”) headspace is the distance between the bolt face and the face of the chamber where the loaded cartridge rests. In a rimless cartridge such as a .308 the headspace is measured to the shoulder of the cartridge. This dimension is important for proper and safe firearm function regardless of the type of cartridge being checked. Too little headspace will not allow the bolt to fully close rendering the weapon unable to fire. Too much headspace can cause excess chamber pressure, as a result of the cartridge not being held firmly in the chamber on firing. This can be particularly dangerous given the chamber pressures generated by centerfire rifle cartridges..

Headspace gauges generally come in 3 sizes:

GO: measures the minimum acceptable headspace. This size is most often used when re-barreling or re-chambering a firearm.

NO-GO: This gauge is used to check for excessive headspace. If a firearm closes on the NO-GO gauge it is an indication that the weapon MAY not be safe to fire. Reloading ammunition for a firearm that fails NO-GO can result in unsafe loads due in part to the expended brass being elongated as a result of not being firmly chambered. Most military surplus firearms that pass NO-GO (the bolt will not fully close on the gauge) are considered safe to fire with either surplus ammunition, or with modern loads that may or may not be intended for reloading.

FIELD: A firearm failing the NO-GO spec can be tested on the slightly more forgiving FIELD gauge. Military chamber specifications are generally looser than commercial firearms, giving them a bit of tolerance for adverse conditions such as dirty chambers, weather extremes, etc. A firearm passing FIELD spec (not closing fully on the gauge) is generally considered safe to fire the ammunition it was designed to fire, i.e. military surplus ammunition of the designated caliber.

These are to be considered GENERAL GUIDELINES and are in no way intended to be an assurance of the safety of a particular firearm. If you have doubts about a firearm’s safety and usability you should have it checked by a professional gunsmith."

[millman]

If your bolt closes on a cartridge then you dont need the go gauge.