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If a tight chambered .125 AR barrel won't quite close on a go gauge (it'll almost close with a .125 bolt) but will close with a .136 bolt would it be reasonably safe to use that way since it headspaced?
Steve............
Steve............
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Last edited by se3388; 08-28-2018, 05:27 PM. -
I think it is OK since the headspace IS proper for a .136 bolt.
That's what the Go and NoGo gauges told you.
Edit:
se3388, you edited out the part where the NOGO gauge would not chamber with the .136 bolt.
I will retract my reply. It might not be safe.Last edited by bj139; 08-29-2018, 12:18 AM. -
Are we doing apples and oranges here?
1. what did the mfr/vendor say it is headspaced for?
2. What happens with the no-go gauge and the 0.136 bolt?
What I gather from your post,
a. the barrel+go gauge+0.125 bolt = no go
b. the barrel +go gauge +0.136 bolt (which has a deeper face cut so naturally there's more room) = "go" or close.
You still might have too much room under #2 above, meaning use of the 0.136 bolt might cause case head separation/ failures."Down the floor, out the door, Go Brandon Go!!!!!"Comment
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Original post has been changed? Why?Comment
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I streamlined the question so it would be a little more coherent, it was too busy and seemed to repeat itself. It says the same thing just less busy.
Barrel is supposed to be used with a .125 bolt but is tight chambered. It will almost close on a go gauge using a .125 bolt.
I tried a .136 and it closed on the go gauge, the chamber is not long enough (too much headspace) to close on a no go gauge (i.e. will not close on a no go gauge). Hope this clarifies things, sometimes I don't explain things plain enough even to myself.
grayfox got it right with b.
Steve........Last edited by se3388; 08-29-2018, 01:19 PM.Comment
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If with the .136 bolt, it will close on a go gauge but not close on a nogo gauge then headspace is correct for that bolt.
It is a simple test. It is not headspaced for a .125 bolt according to your test.
I was just a little concerned because you deleted important information making my answer look incorrect.Comment
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Sorry about that, I was trying to make it easier to understand. The barrel is supposedly a tight chambered Mossberg barrel and it was sold as requiring a .125 bolt. I tried my .125 bolt and it almost locked up, so I tried my .136 bolt and it locked up snugly, tolerances seem to be on the tight side. I'm thinking it might have been mislabeled for a .125 bolt instead of a .136 bolt. Hand guard, adjustable gas block and gas tube should be here next week, I'm like a kid at Christmas waiting on the stuff so I can shoot this one. I already have an AR in 6.5 Grendel and a Mini MkX in 6.5 Grendel also.
Steve........Comment
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Sounds much better now. Agree with Bj, but I would still, for the first round, be very very careful. I don't like mis-labeled things when kabooms are around...
Definitely use a factory round.
Mossberg barrel, what is this? Is this for a bolt gun or ...?
Who made it?"Down the floor, out the door, Go Brandon Go!!!!!"Comment
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AR barrel, I was told by the place where I ordered it that it was made by Mossberg. I already bought a box of factory ammo and I plan to hold it around the other side of a tree in the yard to fire maybe the first 5 to 10 rounds.
Steve............Comment
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Holding around the other side of a tree. Good idea.Originally posted by se3388 View Post
I have also strapped the gun to a rest and used a string around the trigger.Comment
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Don't let the tree huggers sue ya!!!!!Originally posted by se3388 View Post"Down the floor, out the door, Go Brandon Go!!!!!"Comment
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grayfox
Had one two houses down (College Professor) but she retired and has sold her house and moved away.Nobody in this small neighborhood could stand her but that is a very long story. I solved everything by sending the barrel and bolt to Precision Firearms to work his magic.
Steve.....Comment
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Steve,
My take on your situation.
NO GO: Both .125 and .136 bolts fail to close on the NO GO gauge. This is good because they are well within the max headspace specs for this calibre.
GO:
The .125 does not close
The .136 closes.
Use the .136...It's good to go (pardon the pun).
That said, even if the .125 bolt doesn't close on the GO gauge it might still be OK if your factory ammo goes fully into battery. I say this because factory loads and new cases are usually shorter than SAAMI (this way so they can load and fire in almost any gun). You do however want at least .003" of headspace for reliable cycling in an auto-loader but even .001" clearance like in a bolt gun is perfectly safe as long as the bolt fully closes. You can then take those spent cases and squash them down in your sizing die to at least .0025 -.004" less than fired and you can reload them from then on until the cows come home. Perfectly safe.
Here's an example of what I am talking about. I don't have Grendel GO/NO GO gauges but I do have .223. The principle is the same. Measuring the headspace of the GO gauge with the Hornady Comparitor gives 1.4530". Then measure a few unfired Lapua cases and they are shorter than SAAMI at 1.4510". Out of the box Lapua brass is .002" less than SAAMI. The American Eagle is very close to SAAMI at .0005". The Nosler Silvertip are .0015". As long as the bolt closes fully on any of these including the American Eagle they are OK to fire.
As for shooting round a tree...Good idea! I fire the first round of all my new barrels from the hip while turning the head away. If I have gloves handy I wear them too. This, because even if the GO/NO GO work the neck might still not have enough clearance to release the bullet and these gauges only measure horizontal headspace, not lateral headspace.
Do you have the Hornady Comparitor gauge?Last edited by Klem; 09-08-2018, 08:15 AM.Comment
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After looking at brass fired in it (safe load in all my other rifles) I was getting flattened primers and under magnification it looked like the mouth of the brass might have been hitting the end of the chamber (on some brass) so I'm thinking it may not have been throated right so it left yesterday to Precision Firearms.
Steve.........Comment
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