Easy Headspace Check

[kis2]

so ive heard a lot about needing to check the headspace on milsurp rifles, and im a bit confused. im not entirely sure what headspace is, even though i tried reading up, and the instructions online i found to check the headspace on my 91/30 involve gauges and whatnot.

is there an easier way by chance to check the headspace on my rifle? its an all numbers matching 1944 mosin 91/30... if that matters. i never checked my sks ( out of ignorance ) but it ended up being ok...

i just really dont want to have my first shot out of this thing kill me. overly paranoid?

thanks again for all the help guys. and again, im not much of a gunsmith, so if im being irrational or not using proper terms, forgive me.

 

[Doggy Daddy]

Yeah, I'm in the same boat. My "new" MN came with a warning on the trigger guard to have the gun examined by a smith before shooting. What should I look for myself? Or do I really need to have a smith look at it?

 

[Hoppy590]

theres no trick to avoid head spaceing. too little head space is obvious as the bolt wont close with ease. too much head space is where you risk the round not seating and gasses escaping. this could cause injury.

 

[Sistema1927]

If you aren't going to have the headspace checked, or take the time to learn how to do it yourself, then let me suggest the following:

Strap the rifle to something, like a tire, and attach a long cord to the trigger. Fire the rifle using this cord, and then check to see if you have case stretching, case separation, or anything else bad.

 

[ReadyontheRight]

If you aren't going to have the headspace checked, or take the time to learn how to do it yourself,

I think Sistema1927 is asking HOW to take the time to learn it himself.

 

[DMK]

To check headspacing, you really need the proper gauge set for the caliber of your rifle and the proper specifications for pass/fail. The headspace set will include three gauges that look kinda like a solid cartridge (Go, No-Go and Field). When you close the bolt on the "Go" gauge, it should close and lock. If not,your headspace is too tight. If your rifle passes that test, you use the "No-Go" gauge. It should not close and lock on it. Some military guns will close on a no-go and still be safe to fire, but it's not optimal for accuracy. They make them loose like this so they will be more reliable with poor ammo or poor cleaning. If the bolt closes and locks on a "Field" gauge, it's unsafe. Depending on the gun, it may require a new bolt, or some other part replaced to get it back to spec.

There is no other way to properly check headspace.

BTW, different calibers headspace on different parts of the cartridge (some on the rim, some on the mouth,some on the neck, some on the belt, etc). You must use the proper gauge for your caliber. They are NOT interchangable even if similar.

 

[Avenger29]

Easiest way to check headspace is with the set of gauges mentioned above. Some rifles call for a specific procedure, usually outlined in the armorer's manual.

Don't forget to check the firing pin protrusion. This is an issue on Mosins. The bolt tool that should have been included with your rifle has slots to check this.

 

[zinj]

Some military guns will close on a no-go and still be safe to fire, but it's not optimal for accuracy. They make them loose like this so they will be more reliable with poor ammo or poor cleaning. If the bolt closes and locks on a "Field" gauge, it's unsafe.

IIRC, this isn't about reliability. Rather, the NO-GO is just the maximum for a new or rearsenaled gun before it is issued, to ensure there is adequate service life. The Field gauge is the point at which the gun starts to become unsafe, and needs to be taken out of circulation. Basically, NO-GO is for the factory and Field is for the field.

 

[Jeremy2171]

Here is the breakdown of the different gages and thier usage: (written for M1s but applicable to almost every rifle.)

GO= used when installing a "new" barrel to ensure the chamber is cut deep enough for the longest possible cartridge.

NOGO= used when installing a "new" barrel to ensure the chamber is not cut too deep after chambering.

FIELD= used by actual armorers once the rifle is out in the unit to verify that the headspace has not exceded the max allowable limit (1.950" for .30cal)

FIELD TEST BOLT= is an actual bolt that has been ground to have a certain measurement that when used in conjunction with a FIELD gage it will determine whether the reciever has worn too far to be able to correct the excess headspace with only a bolt swap. If the FIELD TEST BOLT closes on the FIELD gage then the reciever/barrel is unservicable and should be returned to Depot level for repair/overhaul.

GO and NOGO are used only when barrel a new barrel and setting headspace.

FIELD gage is ONLY used once the rifle has been issued/left the arsenal.

A rifle that closes on the NOGO but NOT the FIELD is NOT unsafe! Only when the bolt closes on the FIELD do you need to worry or on a bolt that WILL NOT close on the GO gage.

So that being said...for a casual shooter who likes to do thier own tinkering I would have at a minimum a FIELD gage. Then as you decide to spend more money on tools/gages get a GO gage, if you don't plan on ever using a chamber reamer then you can forget the NOGO as that is the only usefull purpose it has. A FIELD TEST BOLT is a neat item to have but very expensive and hard to find.

So in summary:
not closing on a GO= BAD
closing on a FIELD = BAD
closing or not closing on a NOGO= doesn't matter...see above.

 

[judaspriest]

Mr. Jeremy2171, are you suggesting the NO-GO is redundant? That would certainly save some money...

In general, are there any brands to be avoided? I see midway selling PTG, callingcoyotes selling forster (GO and Field), amazon mentions Lyman (but doesnt' seem to have them, in any cal) Or is pretty much any is good.

For someone with a MN M44, it looks like a pretty raw deal to spend 60% of its price on a couple of gauges... I guess I could sell on ebay afterwards, but someone mentioned headspace shoudl be checked periodically (I guess at least the FIELD should be retained).

Any tips for MN M44 and SKS will be very much appreciated!

Many thanks!

JP

 

[silverlance]

i'm a Forster dealer so I want to get that out first.

that said what jeremy said is right. the correct gage to use for your Mosin Nagant is the FIELD 0.074 gage.

It is very easy to do - simply twist and insert the gage under the extractor and then try to close the bolt gently. If it doesn't, you're golden. If it does, time to sell the rifle as a wall hanger, return to dealer, or rebarrel (not practical in most cases).

There are "poor man's" methods of headspacing but I would not recommend it - I am a cheapskate, so that's saying something. Besides, once you buy a gage you can always charge your friends and buddies at the range 5 bucks to headspace their guns - after four or five your gage becomes free. That's how I did it myself - I wanted to be safe but didn't want to pay so much. So I would buy a gage, then make it pay for itself. Now I have lots of friends and acquaintances who come by and borrow my gages (after they paid for themselves, I just loan them out).

here's my one shameless plug - I can sell you one if you want. okay there, have a good day! (and if you do the rope and a tree trick better make sure you are aware of your target!)

ps: watch out for the bulgarian surplus - they're hot and the brass is thin!

 

[rockstar.esq]

I wonder if you could make a chamber cast using cerrosafe only make it long so that you could file the breech face end until the bolt closed on it. Seems like you'd be able to determine the following:
A) Exact headspace dimension of your particular rifle.
B) Throat wear on your particular rifle.

Plus when you're done, you can re use the cerrosafe on other rifles of different chamberings with the same process. Granted, this would require a person to obtain a chamber drawing of the cartridge in question but I'd bet that most milsurp's have credible sources. Seems like I saw a thread a little while back where somebody had found a Mosin Nagant site that had all chamber dimensions for the 7.62x54R.

 

[RubenZ]

Sorry to bring an old thread back.

But what if your putting the barrel that came with the action back on the action? Do you still need to do all that stuff?

 

[Hoppy590]

yes you should. any time you mess with the distance between the bolt and the chamber, you should check headspace. so if you get a new bolt. or bolt head. check headspace

 

[Bill73]

Checking headspace takes very few minutes. Your gunsmith charge for checking it would be less than buying a set of gauges.

 

[Dave P]

Or a cheap approach:

1) try to chamber a factory cartridge. Does it close easily? Good.

2) put 2 layers of masking tape on the back of that cartridge. Does the bolt not close now? Good.

3) does it close with one layer of masking tape?



I think if you pass the first two tests you are good to go. I know I would shoot it.

Dave

 

[davera]

I've done this with several milsurps - Gunsmiths are few and far between where I live

1.) Assuming the rifle and bore are in pretty good condition (you don't buy them if they are in crappy condition right?)
2.) Check the function of the bolt - does it at least appear to close securely and tightly?
3.) Does the receiver look intact and undamaged?
4.) Fire a standard round with plenty of eye and face protection - protective glasses, hat. (this assumes or hopes fervently the rifle will not literally explode or come apart) Good advice for any rifle shooting.
5.) Compare the fired round to an unfired - check if the shoulder is blown out or there are other signs of excess stress on the cartridge.

All my milsurps have passed this test, the worst being the Enfield but an expanded shoulder is more or less normal for this rifle.

Your mileage may vary.