The Russian Mosin Nagant Forum

I am frequently asked if our coin style gauges can be used to check headspace in semi-autos such as the SVT 40 and PSL. The short answer is "yes". The process is a bit different so I will explain it here.

1. First and foremost make sure the weapon is UNLOADED.

2. Check to see that there is NO AMMO in the weapon to be tested.

3. Make sure the weapon is UNLOADED.

4. Hold the bolt back and place the gauge on the bolt face, aligning the notch with the extractor just as you would do with a bolt action.

5. DO NOT LET THE BOLT SLAM SHUT!!!!!!! This will destroy the gauge (at the very least) and possibly cause serious damage to the weapon.

6. I repeat...DO NOT LET THE BOLT SLAM SHUT!!!

7. Gently close the bolt, holding on the whole way.

8. Once the bolt is fully forward give it a gentle forward nudge with the heel of your hand to make sure it is closed as far as possible.

9. Aim the weapon in a safe direction and pull the trigger.

The hole in the gauge is for firing pin clearance, and comes into play now. If the bolt goes fully into battery with either the NO-GO or FIELD gauge in place then pulling the trigger will drop the firing pin and you'll hear and feel it click (dry fire). This lets you know that the rifle has FAILED the test. Again, if the firing pin drops when you pull the trigger it is the same as a bolt action fully closing on the gauge...a FAIL. If using the GO gauge then you want the rifle to fully close on it (dry fire).

Clicks on GO gauge = PASS

Clicks on NO-GO or FIELD = FAIL

And remember to make sure the weapon isn't loaded when checking headspace.

Please also tell us what to use to check the headspace for SKS and AK 47 7.62x39 cals. Thanks JGC

Did you say " unloaded".

Celt wrote:Did you say " unloaded".

I think he meant to say "unloaded"

Thanks Websterz


Dolk

Jolly Green Chopper wrote:Please also tell us what to use to check the headspace for SKS and AK 47 7.62x39 cals. Thanks JGC

These are not rimmed cartridges, Okie provides gauges for rimmed cartridges like .303, 7.62x54r, 8mm Lebel, if he is doing the rimless ones I haven't been told.

I thought the 7.62x39 was rimmed. I thought that was why the ak mags had that curve in it. I guess I never paid much attention to when it was rimmed or not haha. But it isn't haha.

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The 7.62x39mm is a modern round, it's rimless as all modern rounds are since the Germans designed their 8mm Mauser round in the late 19th century. The 7.62x39mm is actually a copy of a German intermediate cartridge used in the stg44 but I wont get into that now.

ponycarman wrote:I thought the 7.62x39 was rimmed. I thought that was why the ak mags had that curve in it. I guess I never paid much attention to when it was rimmed or not haha. But it isn't haha.

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The mags are curved because the cases are tapered.

Ahhh that explains it. Cool, you learn something new everyday

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I've got the Gauges now it's time for a SVT 40 or two (I wish)

That wish can be filled on Gunbroker, all it takes is money