Go Gauge vs No-Go Gauge - Do you need both?

[CWulf]

As I get more into building out an AR (This is really like adult Lego's!) I wanted to ask about Go and No-Go gauges. The question is simple enough, I know what they are supposed to do, but do I need both? Can I just go with the No-Go gage? They are not hugely expensive but I would rather by ammo with $30-40 I wont have to spend if I just by one or the other. Any thoughts?

 

[xtry51]

You need both.

 

[ntomsw]

Forster go/no go gauges.

It's cheap insurance.

 

[glide]

An argument could be made that all you need is a 'field' guage.

 

[acoonradt]

If you bought an upper from a reputable manufacturer and they already installed the barrel then all you should need is the no/go. The manufacturer should have already set the barrel in the upper and confirmed that it will close with a round chambered.

Otherwise you will need both a go and no/go.

 

[ntomsw]

An argument could be made that all you need is a 'field' guage.

That would be a wrong argument. Even if your rifle passes a field gauge, I wouldn't fire it. That puts your rifle at the farthest end of the spectrum of being safe to shoot.

Get a set of good go/no go gauges.

 

[CWulf]

That would be a wrong argument. Even if your rifle passes a field gauge, I wouldn't fire it. That puts your rifle at the farthest end of the spectrum of being safe to shoot.

Get a set of good go/no go gauges.

Ok. Another question, spent some time at the Brownells site, plenty of options there of course. However, Forsters gages look to be .223. I am using 5.56. Are the gages specific?

 

[jasons]

An argument could be made that all you need is a 'field' guage.

And it would be wrong.

 

[Mr. Brownstone]

An argument could be made that all you need is a 'field' guage.

I was told all I needed was a NO-GO. I was corrected by JasonS. I did a little research based on that correction. There are a whole other set of problems associated with too little headspace. None of which I want happening to me, or to someones rifle I have checked. Thank you JasonS. Now I have both.

 

[ntomsw]

Ok. Another question, spent some time at the Brownells site, plenty of options there of course. However, Forsters gages look to be .223. I am using 5.56. Are the gages specific?

They are the same dimensions. At least with Forster.

That's what I have.

 

[7.62x39]

Those who know not of what they speak, should refrain from offering their ill conceived advice in matters of such importance as safety.

You need both both a go and a no-go.
I don't see much use to field gauges (I have never used one, even though I own them in several calibers) If it fails my no-go, I address the problem and correct it. Field is for last resort, life or death situation only.

 

[Mr. Brownstone]

Those who know not of what they speak, should refrain from offering their ill conceived advice in matters of such importance as safety.

You need both both a go and a no-go.
I don't see much use to field gauges (I have never used one, even though I own them in several calibers) If it fails my no-go, I address the problem and correct it. Field is for last resort, life or death situation only.

Unfortunately for me, I was given my bad info in an armorers course. Luckily I was corrected before anyone got hurt.

 

[jasons]

Ok. Another question, spent some time at the Brownells site, plenty of options there of course. However, Forsters gages look to be .223. I am using 5.56. Are the gages specific?

Forster does make 5.56 gauges as well (you have to look for the ones marked NATO.) There are some slight differences, but it's nothing to get too worked up over. I use standard SAAMI .223 gauges in everything.

Details here:
http://www.ar15barrels.com/data/headspace.pdf

 

[ntomsw]

I do also have a Forster 5.56 NATO minimum gauge, and a Forster 5.56 NATO maximum gauge. (5.56 minimum gauge is same dimensions as a .223 go gauge, and 5.56 maximum is the size of a field gauge.)

So I do have both sets. No reason to though. A set of .223 gauges would work just fine.

 

[Hardwired]

I went with the Manson gauges. They have a 3 gauge set called "Down n Dirty" that comes with go/no-go/field and they have clearance around the head so you don't have to remove the ejector.

They don't list this set and you have to call to order from them at any rate ($60 + ship). They sell these to smiths and they are a little cheaper because the finish on the sides aren't completely polished.

http://www.mansonreamers.com/

 

[CWulf]

Thanks for all the help guys, much appreciated.

 

[StevieP]

So the first AR I "built" was with a complete upper (RRA).

This .308 AR I'm building "from scratch." It'll have a DPMS barrel, upper, and BCG. Since they're all the same brand, is it ever "safe" to assume they'll mate up perfectly?

I ordered the armorer's wrench from the GB. What other tool (go / no-go guages?) will I need? Does someone around southern Worcester county have one they'd loan, or just let me come over when the time comes, to use?

 

[EvolutionArmory]

I was told all I needed was a NO-GO. I was corrected by JasonS. I did a little research based on that correction. There are a whole other set of problems associated with too little headspace. None of which I want happening to me, or to someones rifle I have checked. Thank you JasonS. Now I have both.

If all you use is a no go, how would you know when the chamber was headspaced? All the no go tells you is if your chamber is over cut. It doesn't tell you if it is under sized or correct.

As said before, you really need both. A field gauge is not the correct tool for a new build. A field gauge is alright on a proven rifle, not an unproven rifle.

 

[Mr. Brownstone]

If all you use is a no go, how would you know when the chamber was headspaced? All the no go tells you is if your chamber is over cut. It doesn't tell you if it is under sized or correct.

The instructor in the armorers course I took told us that. I looked back to my notes, and he specifically said it. After thinking back, the class was mainly geared towards LE armorers. I think he may have been saying that if you have known rifles that were fine and you were checking them for wear, a no go would be all you needed. That is the only way I can think that his advice would have made any sense.

 

[USMC2111]

A field gauge is all we used for our LTIs and PFIs.. Never had a rifle blow up out of my armory

 

[jasons]

A field gauge is all we used for our LTIs and PFIs.. Never had a rifle blow up out of my armory

Do you only do an LTI after installing a new barrel?

 

[Gammon]

So the first AR I "built" was with a complete upper (RRA).

This .308 AR I'm building "from scratch." It'll have a DPMS barrel, upper, and BCG. Since they're all the same brand, is it ever "safe" to assume they'll mate up perfectly?

I ordered the armorer's wrench from the GB. What other tool (go / no-go guages?) will I need? Does someone around southern Worcester county have one they'd loan, or just let me come over when the time comes, to use?

Stay away from DPMS barrels. I have had three and all came with rough chambers that needed serious polishing before the gun would function reliably.

 

[Archilochus]

Stay away from DPMS barrels. I have had three and all came with rough chambers that needed serious polishing before the gun would function reliably.

I've had problems with their LPK's. I stay away from anything DPMS.

 

[USMC2111]

Do you only do an LTI after installing a new barrel?

Every weapon that came in to our shop would get an Lti unless Iit was due for a PM... even then thats all I remember using... machine guns and the SASR are the only time I remember using both gauges on

 

[StevieP]

Anyone in central MA (southern Worcester County -- Millbury, Grafton, Westboro and surrounding area) got a set of these gauges, and willing to put them to use checking my .308 AR build for me?

Go / No-Go / Headspace check.

 

[wolo]

Before I had all of the gauges, I used just a no-go plus a Hornady headspace comparator tool with a set of calipers to convince myself that most factory ammo is pretty near SAAMI min. When I was able to chamber the factory round and gently rotate the bolt into place (with ejector and extractor removed), and then confirm that in doing so hadn't changed the headspace on that factory round, I was comfortable. Curious what others think of that practice for a first-time, one-off confirmation on quality parts.

Note that you do need at least one precision gauge, since the comparator itself only provides relative numbers.