Go & No-Go Gauges.

[User00044]

Just to muddy the water a little more , here's a SAAMI chamber drawing . Notice it allows spec to spec minus 0.010" . The difference between a go and no go is 0.004" .
I believe the spec to minus 0.010" is to allow for reamer wear during a factory
production run .

 

[White Spider]

I made a set for my .303 during lock down, no issues with the rifle, although it did prove the correct bolt head is fitted.

 

[Stalker62]

Just to muddy the water a little more , here's a SAAMI chamber drawing . Notice it allows spec to spec minus 0.010" . The difference between a go and no go is 0.004".

Thank you.
That is demonstrably helpful, and is actually useful in assisting me making a decision.

 

[Stalker62]

Having spent most of the day searching the Internet for GO & NO-GO (now have to delete my search history), I cannot believe (yes I can) the about of tools out there, and no, I don't mean the gauges.

However, thank God for this chap - Larry Potterfield (always enjoy his videos) knows his stuff and the videography is professionally done - not some Redneck (apologies to our Redneck readers) using a hand-held camera, filming in the crawl space under their trailer, whilst belting out Country & Western music at full blast, all the while 'teaching' you something they themselves have never before done.

Any hoo.

Here comes Larry...

 

[Edinburgh Rifles]

Do you own one of these:

It is a similarly useful device when used at the correct time or when some confirmation of size is required
If there is a problem that requires that confirmation…..then invest in some gauges
However ..if the show fits….stop measuring

 

[Twodogs]

In the military we used to always check headspace on any weapon that had a positive locking system (as opposed to API).
The main reason was nothing to do with initial fit but because they often incurred lots of wear due to high usage and could easily exceed headspace requirements. The MOD was averse to getting sued even in those days.

This became a bit more of an issue with the SA80 (ok, rifle 5.56mm L85A1, for the pedants) as the bolts/carriers were not numbered to the rifle
so it was not uncommon for users to swap bits around, aaargh. This in theory should not have been a great issue, well it wouldn’t have been if manufacturing quality and tolerances had been maintained.

With bolt action rifles and especially the amount we civvies use them headspace will rarely, if ever, be an issue.

 

[Foxyboy43]

View attachment 302090

Just to muddy the water a little more , here's a SAAMI chamber drawing . Notice it allows spec to spec minus 0.010" . The difference between a go and no go is 0.004" .
I believe the spec to minus 0.010" is to allow for reamer wear during a factory
production run .

Gosh I am glad you posted that!

 

[User00044]

Gosh I am glad you posted that!

I don't know what to tell you ! In my spare time I like to take over from @Smellydog playing Devils Advocate , you know, so he can go shooting and have a rest from the forum .


I should keep my head down or he'll want that tenner .

 

[Smellydog]

so he can go shooting and have a rest from the forum .

Nearly worth me sending you a tenner that!

 

[Stalker62]

In the military we used to always check headspace on any weapon that had a positive locking system (as opposed to API).

API?

 

[sh1kar]

Primer ignited when bolt still moving forward to chamber round in blowback auto rifle

 

[Stalker62]

API = Advanced Primer Ignition.


In an API blowback open bolt weapon, when the moving parts group moves forward after being fired, it has significant momentum. If this mass were allowed to bottom out against the weapon’s receiver, it would have no value, but API blowback harnesses that momentum to resist part of the thrust generated by the cartridge’s ignition. To do this, the ammunition is ignited not when the breechblock is home against the barrel, but before, so that the thrust of the round must first stop the breechblock’s forward motion before it can begin to force it to move rearward.

 

[Foxyboy43]

Right then - NoGo Gauge. Words fail (particularly often and for good reason(s) on SD) so see sketches pictures below:-

It is a good idea to try closing the bolt a few times before you add the gauge to let you see how much/little effort is normally required. Then you simply insert the bolt with gauge fitted and gently slide the bolt forward and gently try to close it. If all is good the bolt handle will quickly come to a dead stop - in my two mosins probably after about 25-30 degrees out of the 90 required to fully close. If your bolt fully closes headspace is an issue!
Simples.

PS
I particularly recommend particularly you not doing this with a loaded rifle - particularly as to remove the bolt you have to pull the trigger.
Just saying, you can’t be too careful like…….

 

[HonestJohn]

Right then - NoGo Gauge. Words fail (particularly often and for good reason(s) on SD) so see sketches pictures below:-
View attachment 302128View attachment 302130View attachment 302129
It is a good idea to try closing the bolt a few times before you add the gauge to let you see how much/little effort is normally required. Then you simply insert the bolt with gauge fitted and gently slide the bolt forward and gently try to close it. If all is good the bolt handle will quickly come to a dead stop - in my two mosins probably after about 25-30 degrees out of the 90 required to fully close. If your bolt fully closes headspace is an issue!
Simples.

PS
I particularly recommend particularly you not doing this with a loaded rifle - particularly as to remove the bolt you have to pull the trigger.
Just saying, you can’t be too careful like…….

use of gauges should always be done with a stripped bolt, no firing pin, no extractor claws, etc. only clean bolt face

 

[Foxyboy43]

use of gauges should always be done with a stripped bolt, no firing pin, no extractor claws, etc. only clean bolt face

Hmm. I think that was the danger/beauty of this one - cut to bolt-face size and to accommodate the extractor claw so no bolt dismantling required.

 

[jthyttin]

Bolt dismantling will be required to get rid of the resistance that firing pin, spring etc. create. Just the same if you are trying to setup resize die to match your chamber (and preferably add a bit clearance). The bolt handle should drop on pure gravity, no assistance needed.

 

[jthyttin]

One case where gauges might be needed, is if you have rifle with barrel nut like Savage, and swap barrels. The nut makes it hard to set any precise indicator marks on barrel, and if you gently tighten the barrel on GO gauge and then proceed to torque down the nut -> you get quite good repeatibility with practice. And you want to get similar headspace every time to avoid problems with brass, especially if you're matching the resize process to your chamber.

 

[HonestJohn]

Bolt dismantling will be required to get rid of the resistance that firing pin, spring etc. create. Just the same if you are trying to setup resize die to match your chamber (and preferably add a bit clearance). The bolt handle should drop on pure gravity, no assistance needed.

This above

 

[Jura]

This question comes about thirty minutes too late really.

Has anyone got them?

Has anyone used them?

Did they improve your life?


View attachment 302009View attachment 302010


I have just ordered three sets from the USA, in:-

.308
.243
.303

I fully expect them to change my life for the better - and lets face it, it needs to...

Yes, I had the 'Go' and 'No Go' gauges in .275 Rigby (7 x 57); they saved me a shed load of hard earned when I bought a 275 Rigby rifle from a well-known London gunmaker.
The 'No Go' gauge chambered, so I returned the rifle and got a full refund.

 

[Foxyboy43]

Bolt dismantling will be required to get rid of the resistance that firing pin, spring etc. create. Just the same if you are trying to setup resize die to match your chamber (and preferably add a bit clearance). The bolt handle should drop on pure gravity, no assistance needed.

Actually my gauge does not require any bolt disassembly for the Mosin - if you look at the pictures in my earlier post you will see that the gauge has a cut-out to accommodate the extractor and a hole to do likewise for the firing pin . Simply dry-run a few cockings with the complete bolt to get a feel for cocking and bolt closure then repeat with gauge set in place - if the closing action is stopped you clearly have an issue. Simples.