cannot lock on GO gauge :(

[R2BRO]

Guys, I just assembled AR, bought GO/NOGO set, i disassembled the bolt (although maybe I shouldnt since I saw extractor cutout in those gauges...but anyway), I put the GO gauge and it doesnt lock!

The AR parts I bought from 22mods4all.com and it all came in together, so one set of matched parts...

when I put unused brand new Hornady case into chamber, it DOES lock.. .so any ideas? maybe im putting gauge in a wrong way??

[grayfox]

You're guiding it all the way in with your fingers (against the ejector force), right? Not trying to slam it with the bcg/buffer spriing...
New hornady case shoulders and case lengths can typically be a few 0.001's shorter than Saami to ensure they always fit.
Are you sure it is the go gauge? put up some pics of the 2 gauges. I know it sounds silly but just do a double check.
Also, are the go/nogo's from the same mfr? You can't mix and match.
What about the chamber and bolt, as in bolt face depths. Assume nothing when you say "one set of matched parts." need to verify.
If I get this right, ie, a chamber set for a 0.136 bolt face depth yet you have a bolt with 0.125" face depth, it will not close. Go ahead and measure the bolt face depth with your calipers.

ok... I looked up the web site and they state that they use BCA barrels and uppers... BCA as you can read on here is hit and miss as to quality controls...
Sometimes good, sometimes well, not so good.

Maybe a couple other AR builders will chime in but that's what comes to mind as I sit here.

[NugginFutz]

I had a similar occurrence with a barrel from BHW. Would not close on either gauge, but fired factory ammo without issue. A return visit to the vendor for a touch up, and all is well.

[R2BRO]

Hi guys!

my answers:

* yes, I am guiding it all the way with my fingers, I do not close using spring
* putting picture of a gauges

* it was a GO gauge of course
* same manufacturer, ordered together
* my bolt is Type II, so is chamber/barrel
* i measured distance between bolt face bottom and bolt edge just by putting caliper near it and judging by eye, it was roughly 0.137 or so

The Hornady lilve ammo chambered well on the range.

Anyway guys.... I decided to just test it, and it worked! No explosion or anything, all 89 rounds chambered well!

I will post another thread about my first build in a neighboring thread now!

[Klem]

R2,

I can see a couple of situations how this might be;

1. The gauge makers accidentally marked a NO GO gauge as, 'GO'.
2. Your chamber has been reamed shorter than SAAMI.

You might know this but often ammunition manufacturers load rounds slightly shorter than SAAMI to make sure they fit in every gun, including yours. They can't make them too short however as case stretch will occur and maybe even rupture in a perfectly normal chamber.

Here is a chart of measurements taken with a Hornady/Stoney Pt comparator. I have used 223 as I don't have any factory ammo in Grendel. At the top are the min and max permissible headspaces published by SAAMI. NO GO is in between min and max so it's really a voluntary headspace suggested for new guns.

You can see that 2/3 of the factory loads are less than, or equal to SAAMI minimum headspace. Add to that list Lapua brass for handloaders which is just under SAAMI at 1.451". 1/3 of the factory load are just above min SAAMI threshold but definitely nowhere near max SAAMI ('FIELD').



If your chamber has been reamed shorter than SAAMI and it sounds like that factory ammunition is equal or slightly less than your headspace then it should be safe to fire. I agree with Nuggin however, it pays to get that chamber fixed or at least explained by whomever you bought it from. I've never heard of it but I note the warning on Brownells technical sheet that slamfires have occurred when ammunition that is a bit too long for the chamber is slammed into battery in a semi-auto. In a bolt gun it is more gentle and not an issue The bolt will either close or not on ammunition that is slightly bigger than the chamber.

Do you have a set of calipers that you can check those two gauges are actually different sizes, regardless of what they've engraved on the side?

[NugginFutz]

Here is one more thing to consider. IF this Grendel is the only one you will own, then no worries. Fire-formed brass will work just fine in that chamber and new factory rounds May or May Not, depending on what level of adherence to the specifications the mfgr chooses for their brass.

If you decide to get a second Grendel, however, things could get complicated as they did in my case. Fire-formed brass from two different chambers will need to be kept segregated from each other, as one chamber will be shorter than the other. I found this out the hard way when reloads from one rifle would not chamber in the other. This was one of the motivations I had to send the short chambered barrel back to be re-finished.

Some will say to keep brass with a given rifle, regardless, but I do not have enough brass to keep all my different rifles fed on their own special diet of brass. Instead, I strive for uniformity across all chambers, and compromise when resizing the brass so they will chamber well in all my rifles.

[Sticks]

Here is one more thing to consider. IF this Grendel is the only one you will own, then no worries. Fire-formed brass will work just fine in that chamber and new factory rounds May or May Not, depending on what level of adherence to the specifications the mfgr chooses for their brass.

If you decide to get a second Grendel, however, things could get complicated as they did in my case. Fire-formed brass from two different chambers will need to be kept segregated from each other, as one chamber will be shorter than the other. I found this out the hard way when reloads from one rifle would not chamber in the other. This was one of the motivations I had to send the short chambered barrel back to be re-finished.

Some will say to keep brass with a given rifle, regardless, but I do not have enough brass to keep all my different rifles fed on their own special diet of brass. Instead, I strive for uniformity across all chambers, and compromise when resizing the brass so they will chamber well in all my rifles.

I am in the same boat. A PF cut Bartlien and a Lilja cut Lilja. .017 diff between them on fired shoulder length. Sizing for the Lilja - shorter of the two - with only .001 +\- .0005 bump. Howa is way shorter, and kept separate.

I got lucky that my already loaded ammo works.

[R2BRO]

I measured my GO/NOGO gauges with caliper:

GO gauge: 1.3395
NOGO gauge: 1.3375




does it sound right even??

[Tex Nomex]

The go/nogo is usually measured at a specific point along the shoulder, so I'm thinking the overall length of the gauges is not important in itself. They probably created the gauges from the same blanks.

Measure the distance on both gauges from the head to the shoulder break. If it's the same, the go gauge is probably mis-marked.
What's the difference among those readings and the head to shoulder reading of a spent case? Of a new, unfired round?

[Kswhitetails]

The only way to compare these two gauges correctly would be with a head space comparator, am I correct?

[R2BRO]

Well, I do have Hornady Headspace Comparator but I have only A330 (for .223) and D400 (for .308) heads. I do not have D350 head for 6.5G

In any case I decided to still use A330 just for a curiosity, and here are results:

GO: 1.229
NOGO: 1.233

Klem, I know not the right head was used, but even with A330 head, can it be concluded that GO and NOGO most likely turned out to be same?

[centerfire]

The go/nogo is usually measured at a specific point along the shoulder, so I'm thinking the overall length of the gauges is not important in itself. They probably created the gauges from the same blanks.

Measure the distance on both gauges from the head to the shoulder break. If it's the same, the go gauge is probably mis-marked.
What's the difference among those readings and the head to shoulder reading of a spent case? Of a new, unfired round?

Correct, measure the gages from the datum line at .350 diameter on the shoulder.

[R2BRO]

Alright guys, today I got a B350 Hornady bushing head. Here are results:

GO:


NOGO:


Results:

GO: 1.214"
NOGO: 1.218"

so the difference is just 0.004? Does it sound right? Or do you think my Manson headspace gauges are messed up?

[Sticks]

Contact Manson

[grayfox]

Mine measure:
GO: 1.2155"
NOGO: 1.2205"

Allowing for measurement tolerances (2 different calipers, yours v. mine) I'd say yours measure ok.

Contact Manson just to be sure.