Help. Mosin headspace question

[Casull]

I need help with measuring headspace on a Mosin Nagant without the use of guages. I read a post some time back (not sure if on G & G or somewhere else) about measuring headspace with a lead disk and a dial caliper (measuring the compressed thickness after closing the bolt). Anyone familiar with the procedure or where I can find the post (article?). Any help will be appreciated.

[troy2000]

Originally Posted by Casull

I need help with measuring headspace on a Mosin Nagant without the use of guages. I read a post some time back (not sure if on G & G or somewhere else) about measuring headspace with a lead disk and a dial caliper (measuring the compressed thickness after closing the bolt). Anyone familiar with the procedure or where I can find the post (article?). Any help will be appreciated.

But I'm not familiar with the technique. You'd want a very soft lead, and you might want to pull the firing pin anyway.

To tell the truth, I have eight Mosins in the safe and I've never headspaced any of them. If the bolt closed on a round (and they all did), I put on a pair of shooting glasses and some ear plugs, and pulled the trigger.

Any particular reason for wanting to do it?

[29er savoy]

yankee engineers at YankEng@aol.com sell coin style gauges that do not require you to remove the firing pin and extractor.

[Casull]

Any particular reason for wanting to do it?

Just being extra cautious I guess. I just picked up a laminated M44 to go with my other M44, and I have not shot either of them yet (even though I have had the first one for over a year now). I have a couple of spam cans of Hungarian milsurp that are supposed to be delivered tomorrow and thought I might go out this weekend. Troy, you seem to represent about 9 out of 10 guys on this issue. Maybe I'll just throw a sandbag over the bolt for the first shot and then get to business. Makes me feel alot better knowing that you have 8 and have never had a problem. Funny thing is I have a couple of K31's and a couple of Yugo M24/47's and fired those without checking headspace, and with little or no trepidation. If I make it out this weekend I'll let you know how it went. Thanks.

[Mooseman684]

When you load your first round and the bolt has some resistance when you close it, you can pretty much figure it is ok. If the bolt won't close without really forcing it you can bet that headspace is too short. If the bolt is very very easy to close, you may have excessive headspace.
This is a RIMMED cartridge so the thickness of the rim from the barrel to the bolt face is where these space !
Fire one round and measure or compare case shoulder and length to a live round. It will tell you real quick !
Rich

[billy]

i just tie em to a tree and do the old string trick. ive got 5 of em and none of them have a problem.

[allan1898]

I always check the head space, but have never found one with a problem. The gauge is very inexpensive, you need the No-Go, and then if a round will chamber, there's your Go. I have over a dozen Nagants of various models. Has anyone out there found one that checks excessive head space? I've yet even to hear of one, but I still check!

[billy]

ive never heard of one either. but i still tie em to a tree

[Casull]

The only problem is that the local range will not let me tie it to a tree and remote shoot.

[billy]

i keep forgetting that not everyone lives in the woods. sorry bout that...

[Mooseman684]

If you are scared of it, Set it up on a benchrest, load it, place a sandbag over the action and fire it ! Remove the sandbag and extract the shell and examine it closely. I have 6 different mosins and not one has had a headspace problems...

[jellydonut]

Dad taught me to check headspace using Plasti-gage. It's available at any auto supply store like Autozone or NAPA. It's a thin plastic rod of malleable plastic which is meant for measuring engine valve clearances or something.
Anyway, there are at least two sizes available at the store. They are different sizes for measuring different ranges. I think one is for 1-3 thousandths of an inch, and the next step up is 4-8 thousandths or something. Anyway, you break off a tiny little piece of this rod (It'll be about $2.50 per package of plastigage) and somehow stick it to the back of the cartridge where the boltface will make contact when you close the bolt. (We used spit so it wouldn't take up any extra space and give a false headspace measurement). Make sure you stick it onto the cartridge so that the circular part of the plastigage rod is touching the back of the cartridge, not the flat part where it broke off. (that's so it always squishes out the same amount in the same amount of space, from the same starting diameter--the diameter of the rod)
So you carefully insert the cartridge into the chamber and close the bolt, making sure that the little pellet of plastigage that you stuck on the back is still in the right spot, and you close the bolt. Wait a second for it to squish out completely, and then you can remove the piece, compare its width to the printed ruler on the plastigage package, and find out your headspace pretty accurately. In each package there's probably enough stuff to check the headspace on 100 guns.
I THINK, and you'll definitely want to double check this, but headspace for bolt-actions should be from 1-2 thousandths of an inch, and for semi-autos are acceptable somewhere around 3 or 4 thousandths of an inch. Anything more than that is dangerous. This is just from my recollection of what dad told me. DO NOT TAKE THIS AS ADVICE, and I AM NOT A QUALIFIED GUNSMITH. ANYTHING I HAVE SAID HEREIN IS NO GUARANTEE OF SAFETY. USE OF THIS TECHNIQUE IS AT YOUR OWN RISK.
Disclaimer aside, I've used this successfully (at least they haven't blown up yet) on a mosin and another hi-power milsurp bolt action rifle. It's at least a nice peace-of-mind country-boy test that doesn't cost much.
JD

[ruger22com]

spend 20 bucks and get a field gauge from brownels...dont screw around with headspace questions.

[Devin]

I am a gunsmith, and "ruger22com" speaks the truth on this.

[GoodAim]

I know that my M44 came with all the tools and it has a tool in it that is used to check the headspace. I did use it you check the space. It seemed to be right on the money. This is the first time I have ever considered checking the headspace on a old rifle. I didn't even know what it was until I read a post on here. I had another M44 years ago and never checked the headspace. Fired perfectly. Get on Ebay if you want the tool they have the complete kit on there and then go to 7.62x54r.net and there is a complete explanation as to how to check the headspace using the tool from the kit. It's the cheap and easyway to check. Nothing better than alittle piece of mind. If you are confident in your rifle you will be a better shooter and if that is what it takes to be confident then by all means do what you feel is required. My 2 cents.

[just_a_car]

GoodAim, I believe what you may be referring to is the firing pin gauge/screwdriver. It's use is shown here, near the bottom of the page.

A true headspace gauge for the mosin will be inserted into the chamber or attached to the boltface and will tell you if the distance from the boltface to the chamberface, where the rim seats, is within tolerances. They discuss it briefly here on question 18. Generic headspacing is talked about here (They also do a pictorial of headspacing an M44 on that page).

[Tex in Maine]

if your refering to the tear drop shaped tool with the notches in it that is not a head spaceing tool, that is for checking pin protrusion, way different.

[Vintovki]

These folks make headspace guages for the 7.62x54R they are well made and affordable.
To Products and Services by Yankee Engineers.

[waltham41]

Hello, I am new here, and only have 3 mosins, but I was told that the mosins do not have the gas escape that the mausers do, and if you have a failure caused by excessive head space, it is possible for the firing pin to be driven by the escaping gas out of the rifle and into your face.

I cannot say if this is true, but it only cost me 25 bucks to get a field head space gauge that makes me feel safer as to the condition of the rifle.

I also fired my first round with the butt of the rifle off on my arm so my face wasnt directly behind the bolt, and then inspected the case to make sure.

They are a real fun rifle to shoot, but they are old rifles so a certain amount of caution is reasonable.

I only have 2 eyes and one face to loose.

(I have 5 -8mm mausers and bought the field head space gauge for them also)

[GoodAim]

Oh my bad you are right. I still think though if it closes down firm and the bolt head is not worn it would be ok. Do you think that would be a good assumption..... using that word carefully. LOL