New rifle question

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sfbruner

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I just picked up my first gun ever...the mosin nagant. I am currently working on cleaning the gunk out and reading up all about my new toy. Having said this i came across a write up on head space. Does anyone know where i can pick up the gauges?

I also ordered the svt so gauges for both rifles would be ideal.

Thanks,

Bruner
 
sfbruner said:
I just picked up my first gun ever...the mosin nagant. I am currently working on cleaning the gunk out and reading up all about my new toy. Having said this i came across a write up on head space. Does anyone know where i can pick up the gauges?

I also ordered the svt so gauges for both rifles would be ideal.

Thanks,

Bruner
Click to expand...
I never bothered to check headspace on my milsurps. Gages are useful if you rebarrel or replace the bolt otherwise i would not worry. Mosin and SVT have been refurbished so headspace should be ok. As for the gages, you could check Brownell, Ebay, but like i said, i wouldnt bother but its me.
Joce
 
Easiest way to check headspace on a Mosin.
If the round chambers without using a 2x4, fire it. Inspect the empty casing. If there is no noticeable deformation, cracks, ruptures, you are good to go.
Always wear eye protection.
 
points said:
Easiest way to check headspace on a Mosin.
If the round chambers without using a 2x4, fire it. Inspect the empty casing. If there is no noticeable deformation, cracks, ruptures, you are good to go.
Always wear eye protection.
Click to expand...

If you don't get all the gunk out of the chamber you might need a 2x4 to get it back open. :D
 
Couple of points:

Headspace is critical with RIMLESS ammunition because of the possibility of the round going too far into the chamber and not being supported when it is fired.

RIMMED ammunition does not have this problem because that ugly, old-fashioned rim PREVENTS the thing going too far into the chamber.

The rifles currently available are Soviet Red Army War Reserve rifles. I REALLY doubt that the Red Army would have a million or so War Reserve rifles on hand..... and REBUILD them all..... without bothering to check the headspace.

You really should be good to go with either rifle...... or both.

Happy shooting!
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Headspace is a much over-rated topic here on the fourms, and a great many of the people who post such cautions have very little of actual knowledge and understanding of just what it is or how it is really measured.

One thing that headspace really does is add one more post to those of the competitive people who are headed toward a Zillion posts in their numbers and "Check the Headspace" is a good post for adding to their total.

Now if you have a Browning Machine Gun, it is wise to check and set the headspace, because you could end up with a case stuck in the barrel with the head ripped off it at an inopportune moment. However, since you have a Mosin Nagant, if you are really wary of first firing it, take an old rubber tire, attach the rifle to it with bungee cords, tie a string to the trigger, and load and fire it first this way.

Most of the Mosin-Nagant rifles for sale lately are Arsenal refinished, so they would have been checked. However, I will caution anyone who buys one is to really CLEAN the cosmoline out of it, ESPECIALLY THE BORE. I have seen what happens when an Idiot fired one with the bore still plugged with preservative. Of course, he did not check the bore, but then again, he complained loudly that it was not HIS fault, but that of the rifle and the dealer who sold it to him.
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The best source for headspace gauges is Brownells. These are considered as tooling, so there are no export/import issues.

When you are dealing with a pressure bloom of 40-50,000 PSI a couple of inches in front of your face with the possibility of serious injury to self or rifle from the release of hot gases and brass particles from a ruptured ctg case, headspace is a topic worth considering.

The only way to verify headspace is by the use of proper headspace gauges for the caliber in question. Headspace is established within parameters of minimum or "go" and maximum or "no-go" at the time that a rifle is manufactured or overhauled at arsenal. This is done by using the appropriate "go" and "no-go" gauges with the bolt which is installed in that particular rifle. Once in use, safe headspace limits can be verified by the use of a "field" gauge which is slightly longer than the "no-go" manufacturing/overhaul measurement. Using the .30-06 as an example, "go" measurement (bolt must close w/o resistance on the gauge) is 1.940, "no-go" measurement is 1.946 (bolt must not close on gauge) and the "field" measurement is 1.950 (bolt must not close on gauge). These measurements are taken from the face of the bolt to a datum line on the shoulder of the gauge. If the rifle/bolt combo qualifies on both the "go" and "field" gauges it is within headspace limits and is safe to shoot. If it qualifies on the "no-go" gauge, so much the better.

Once in use headspace can increase towards the maximum limit thru aggregate wear on the following areas of the rifle; the chamber depth (least likely), rear face of the bolt locking lugs (likely), bolt face (unlikely) and the locking lug seats in the receiver (likely). Obviously the critical dimensions can be changed by indiscriminate swapping of bolts and/or detachable bolt heads w/o verification of headspace measurement with gauges. This is why many types of rifles have the bolt numbered to match the rifle s/n at time of manufacture.

A rimless ctg, like the .30-06 or 7x57 Mauser, headspaces on the case shoulder while a rimmed case, like the 7.62x54 or .303Brit, headspaces on the rim. The fact that a .303 Brit or 7.62x54 case cannot enter further into the chamber as a result of it's being seated on the rim is not a positive assurance of correct/safe headspace. In these cases, accumulated wear on the rear of the bolt locking lugs and/or the bolt lug seats in the receiver, can and will contribute to a change of headspace dimensions (distance from the bolt face to the base of the ctg case) thru use. Should excessive headspace be created by wear in these critical areas, then the case has the possibility to expand beyond limits and rupture when fired.

If you are into shooting in a serious way it is a prudent (and cheap) precaution/insurance to have a set of "go" and "field" headspace gauges on hand for each caliber that you shoot so that correct/safe headspace can be established at time of aquisition and periodically while in use. I've been at this a long time and have a set of gauges for all 8 of the MILSURP calibers that I shoot. Sorry, but I just don't make an act of faith that a rifle that may have last seen competent military technical control 70 yrs ago is still within safe headspace parameters, and this especially includes the .303 Brit where a matching numbered bolt may have a different size bolthead screwed on in a heartbeat. Over a period of time there are many opportunities for ignorant dealers/owners/whoever to #### this up, to say nothing of the actual dimensional changes which might occur in a specific rifle/bolt combination as a result of use. One shining example of this was a widely reported problem with ex-Greek M1903 Springfields from the US CMP having chambering issues in spite of the fact that the barrels appeared to be new. It turned out that those ever- diligent Greek military armorers had installed new barrels, but had then failed to set up the correct headspace by finish reaming the chambers:redface:. Too much ouzo or something at coffee break I suppose. I'd assume that this same type of screw-up was within the realm of possibilities for Igor the armorer somewhere in Russia.

When using headspace gauges the bolt should be stripped so that spring pressure and extractor interference can be eliminated and the bolt can actually be "felt" on the headspace gauge when using light finger/thumb pressure on the bolt. The bolt face, lug seats, bolt lugs and chamber should also be clean of crud. Also, the bolt should never be forced on a gauge. When resistance is felt to light pressure, STOP. Assuming that headspace is within established limits, you can maximize case life/case stretching when reloading by necksizing your brass after the initial firing in that particular rifle. Do not necksize for a semi-auto like the Garand or M14 clones as the bolt lacks the camming power of a bolt action to close on a case body which has expanded towards the max limits as a result of only the neck being resized.
 
I have a story that might be of interest. Many years ago I acquired a Mannlicher-Carcano rifle in 6.5mm with a mismatched bolt that didn't slide very freely in the receiver. I took it to a friend who was an old RCEME armourer who not only knew a lot about fixing rifles, he actually understood it all. He fixed the bolt sliding problem in the way you would expect and then asked about the headspace. Neither he nor I had proper headspace gauges so he improvised. First he removed the firing pin from the bolt in order to avoid surprises. Then he took a new-looking 6.5mm Italian military cartridge from his cartridge collection and slid it into the chamber. He gently closed the bolt. It closed easily. He said this showed the bolt met at least the minimum headspace required. Next he aplied a single layer of scotch tape to the base the base of the cartridge and repeated this process. Again the bolt closed easily and the scotch tape was not scored at all. When he tried it again with a second layer of scotch tape, the bolt closed easily but the tape was lightly scrated by the bolt face. He said a layer of scotch tape is .004" thick so the difference between the minimum headspace and the maximum on the rifle was less than .008" which was fine for any rifle. I'm not recommending this method to anyone but, when I later fired the rifle, the fired casing showed no signs of being stretched anywhere it shouldn't have been.
 
There can be dimensional variations between ctgs of the same caliber as a result of manufacturing tolerances, but if a round chambers w/o resistance that would normally indicate that minimum or "go" headspace exists. What you describe is a quick and dirty way of trying to measure max headspace. In your case it worked out, but the only infallible way is to use a "no-go" or "field" headspace gauge which is precision ground to known dimensions. In the absence of "no-go" or "field" gauges one can use a "go" gauge with shim stock of known thickness against the base of the gauge to get a feel for the actual degree of headspace that exists. It is always best to check this with the actual gauge though.
 
Thanks purple.

I actually ordered up a.set of okie gauges a few days ago. I wont fire this piece of history without checking. The rear retainer spring is broken on it also so i have to wait for the parts.
 
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