Headspace gauges for 7.62x54r Mosina Nagant rifles

[Hang Fire]

As I have several MN rifles and look at others when the chance arises. Most of the rifle bolts have a forced match for s/n, but some I haven’t fired are mismatched numbers and gives me a little concern.

Decided a set of headspace gauges were in order. after looking on the Web where several people had made their own, I considered doing likewise. They varied from tape on cartridge head face to making them from washers and etc. of correct thicknesses. The tape idea is pure **** and unworthy of consideration, majority of the metal ones did not consider the bolt/cartridge head face 18.5 (some state 20) degree mating angle, which would give an erroneous headspace.

I then looked at commercial headspace gauges and found a Firewerks three piece set (go, no go and field) on Amazon for $45.00 with free shipping, so the decision to buy was an easy one.

[pretzelxx]

$45 on an old mismatched rifle is a better deal than blind in one eye and missing a finger. Not everyone sees it that way, glad it was an easy choice!

[tomme boy]

There was someone on here that makes the HS gauge for the Mosin. I can't remember who it was. Maybe he will see this post and have a say. I have never heard of a Mosin out of HS. They do have deep chambers, but the HS is right on.

[Mr opinionated]

This is were i found mine gauges good luck


http://www.okiegauges.com/



MR. O

[LAGS]

I bought the three 7.62x54 gages years ago from either Midway or Brownell's
I have found many a MN that had headspace that would close on the Field Gage.
But being a rimmed cartridge, it is more forgiving than a rimless headspacing cartridge.
IE, the case can Fire form to fit the chamber with loose headspace or a too deep chamber.
Lately, I only see people offering the Field gage in this caliber. That is the MAX headspace gage.
The washer method works for a rimmed cartridge, and the Tape method will work IF you know what you are doing, but only as a Preliminary check.
But " Correct " Headspacing is more important if you are going to be firing Steel Cases Surplus ammo.
The cases dont stretch or flex and rupture easily.
If you are using the Tape Method, You have to use an Unloaded, " UNFIRED " case to get any kind of correct reading.
Do Not use a "Previously Fired" Case.
You can also use a unfired case, and shims cut out of an automotive feeler gage.
You do not want more than .008 " between the back of an unfired case and the face of the bolt.
If the bolt closes on an .008" shim then your headspace is too much.
Also.
You NEVER Force the bolt closed on a headspace gage of any kind, and it is always best to remove the Extractor from the bolt face for a Proper reading.

[WineMan]

These are the ones I have. http://www.yankeeengineers.com/product/ Not sure if they are still in business. I have a NO-GO and it is 0.071" thick. My Field for a 30-40 is 0.074". Just remember that you should use very light pressure, any resistance to closing the bolt and it passes, a stripped bolt is recommended so the spring does not interfere.

These look similar http://www.ebay.com/itm/like/330894784787?lpid=82

http://firewerks.net/shop/firewerks-headspace-gauges/

Okie Gauges also make them http://www.okiegauges.com/ but Google says the site may be hacked???

I had three Mosins (M38, M91/30 and a Finn M39) and I could not interchange the bolts. All of them passed the NG check though.


Dave

[MaryB]

Okie gauges are good, I have a set.

[leadman]

I do use the metal duct tape as a preliminary check on a rifle that I can't measure easily with automotive feeler gauges like the break opens. The tape varies in thickness from roll or brand so measure it. Most of it is .004" thick so if you have to use more than 1 piece to get a light resistance on the bolt closing you need to have it checked with proper gauges.

Most of the ammo and new cases I check, either surplus or commercial, are either out of spec or borderline so keep this in mind.

The tape method is handy when you are setting up your dies for a new gun. It is very possible to create excessive headspace by full length sizing the case with dies or shell holders that are marginal. I have seen top name brand dies do this. On my Contenders and Encores it is easy to check the headspace by using an automotive feeler gauge between the standing breech and the head or the case. I usually size to .0015" clearance, or headspace.

[Hang Fire]

Be a cold day in Hades before I would ever used squishy tape for any reason related to headspace.


Quote: It is very possible to create excessive headspace by full length sizing the case with dies or shell holders that are marginal.


Uh, the 7.62x54r headspaces on the rim.

[Outpost75]

I have a JGS "Go" 0.063" gage which I would sell, as I've checked my three rifles and don't plan on buying any more.

For NoGo a 1cm diameter 0.2mm thick (about 0.008") steel shim is placed in the boltface before placing the gage under the extractor. You can cut the appropriate NoGo shim from a piece of feeler gage, flat stoning the cut edge and checking thickness with a micrometer.

[LAGS]

@ Outpost 75
The Extractor should Always be removed so there is no chance of it binding something, and giving you the feeling that the headspace is good.
If you are going to take the time to check a critical measurement with the proper gage, then wouldn't it be worth the extra time to make sure you are Only measuring the headspace .

[Clark]

http://i757.photobucket.com/albums/xx220/ClarkM/762x54Rheadspacegaugedrawingandpics6-23-2011.jpg
I make my own headpsace gauges for the MN, based on the thickness of my Lapau brass.
I have one that is a turn on the barrel threads large. The extractor gets in the way of everything and all the receivers are clocked differently.

[LAGS]

Now that gage is set up to eliminate any stress or binding that can be caused by the extractor.
The Clymer ones do not have the extractor relief, so it is best that the extractor be pulled off.
The using the washer method, Take the extractor off also.