Trouble Shooting 308 AR headspace

[Kansas_Born]

I built my own 308 AR out of a conglomeration of parts. Let me be the first to say, I know it’s not the same as small frame ARs. I am using a Wilson Arms barrel and a tool craft bcg, JP rail and palmetto upper/lower. I was trying to build it on the cheap and I’m paying for it in down time. My first outing I tried to chamber my first round it would not go fully into battery.
I’ve read several threads on large frame failures and decided the next step (probably should have been the first step while putting everything together) was to check headspace. I pulled the barrel and stripped the bolt.

Go gauge in the barrel.

Go gauge and stripped bolt.

No go gauge

No go gauge with bolt.

168 gr Sierra matchking

I am at a lose. I know on bolt guns that I shouldn’t be able to close the bolt on no go and be able to close on go. I can see a physical difference without the bolt in place between the two gauges but once the bolt it in the barrel they look the same. What am I missing here?

 

[Waorani]

Does bolt rotate into lock on go gauge and not on no go?

 

[Kansas_Born]

That would be a crucial step wouldn’t it? It doesn’t rotate into lock for either. Contact retailer or manufacturer?

 

[Mike_in_FL]

I am at a lose. I know on bolt guns that I shouldn’t be able to close the bolt on no go and be able to close on go. I can see a physical difference without the bolt in place between the two gauges but once the bolt it in the barrel they look the same. What am I missing here?

Most manufacturers actually cut the chamber for 7.62x51 rather than .308. So that people can run surplus. If you're concerned about it, buy a .308 field gauge and make sure it doesn't close on that. IIRC, .308 no-go is 1.634 and that's like a go in 7.62x51.

EDIT: Looked closer at your pics, are you even rotating the bolt when you're checking headspace? What happens with the stripped bolt in the upper assembled? Will it close then?

 

[Waorani]

I've had some Craddock bbls that were tight and wouldn't go in by hand on go gauge but after talking to him, turned out they were still fine. Shouldn't be but I've also seen differences among different brands of gauges. Call to mfg wouldn't hurt but I'd bet you're good.

 

[Kansas_Born]

Most manufacturers actually cut the chamber for 7.62x51 rather than .308. So that people can run surplus. If you're concerned about it, buy a .308 field gauge and make sure it doesn't close on that. IIRC, .308 no-go is 1.634 and that's like a go in 7.62x51.

EDIT: Looked closer at your pics, are you even rotating the bolt when you're checking headspace? What happens with the stripped bolt in the upper assembled? Will it close then?

I’m new to this and forgot to rotate the bolt. I went back and tried to rotate into battery by hand and neither gauge would allow for it.

 

[Kansas_Born]

I've had some Craddock bbls that were tight and wouldn't go in by hand on go gauge but after talking to him, turned out they were still fine. Shouldn't be but I've also seen differences among different brands of gauges. Call to mfg wouldn't hurt but I'd bet you're good.

Should I reassemble the rifle and see if stripped bolt/carrier will lock up on the go gauge?

 

[Mike_in_FL]

I’m new to this and forgot to rotate the bolt. I went back and tried to rotate into battery by hand and neither gauge would allow for it.

Then it sounds like it's short chambered. That makes more sense. Can you exchange it? Other guys here had great success with Wilson Arms barrels before.

 

[Mike_in_FL]

Should I reassemble the rifle and see if stripped bolt/carrier will lock up on the go gauge?

Yes. I think for an AR15 you should have to apply like no more than 16 pounds of pressure to the back of the carrier to get the bolt to close. I would just use hand/thumb pressure with the stripped bolt assembled to the carrier in the upper. Although it looks like you've already pulled the barrel from the upper?

 

[Kansas_Born]

Yes. I think for an AR15 you should have to apply like 16 pounds of pressure to the back of the carrier to get the bolt to close. I would just use hand/thumb pressure with the stripped bolt assembled to the carrier in the upper. Although it looks like you've already pulled the barrel from the upper?

Yes, pulled it to start from scratch. I can reassemble though. I purchased this in part because of @padom’s review. I’ve had this barrel for too long to return to JSE. I tend to buy parts for projects as money allows. I can call Wilson arms on Monday and see what they say.

 

[Mike_in_FL]

Yes, pulled it to start from scratch. I can reassemble though. I purchased this in part because of @padom’s review. I’ve had this barrel for too long to return to JSE. I tend to buy parts for projects as money allows. I can call Wilson arms on Monday and see what they say.

Ok, I gotcha. When you tried to shoot it initially were you using factory ammo? How wet with lube was the bolt and carrier? I always start a brand new AR off dripping.

If you reload and you own the Hornady tool for headspace, you could size the brass down until it fit and the bolt will close and measure that.

Also, this does close on an empty chamber?

 

[Kansas_Born]

Ok, I gotcha. When you tried to shoot it initially were you using factory ammo? How wet with lube was the bolt and carrier? I always start a brand new AR off dripping.

If you reload and you own the Hornady tool for headspace, you could size the brass down until it fit and the bolt will close and measure that.

Also, this does close on an empty chamber?

Closes on an empty chamber but would not close on the 168gr Sierra match kings. I don’t reload currently as I only have a single stage press and I’m not that patient. I thought it was wet enough but I suppose that could have been the issue?

 

[Mike_in_FL]

Closes on an empty chamber but would not close on the 168gr Sierra match kings. I don’t reload currently as I only have a single stage press and I’m not that patient. I thought it was wet enough but I suppose that could have been the issue?

I would just torque the barrel nut and leave the gas stuff and handguard off if possible and see if it will close on the go gauge with no more than 16lb. pressure on the back of the carrier. If that works try the no-go. If neither will close it's short chambered. You can probably send it back to WA. I would think they can cut it a little deeper without issue if that's what's needed.

I mean wet for break in and general cycling. Have to be able to chamber first.

 

[Waorani]

On assembled gun, are you dropping bolt from full rear on round or lightly trying to chamber? Drop from fully retracted and if it goes fully into battery, shoot a round or two to test. I'm betting you just have a tight match chamber.

 

[Kansas_Born]

On assembled gun, are you dropping bolt from full rear on round or lightly trying to chamber? Drop from fully retracted and if it goes fully into battery, shoot a round or two to test. I'm betting you just have a tight match chamber.

I tried bolt release to chamber a round and charging handle to the full rear.

 

[Waorani]

I tried bolt release to chamber a round and charging handle to the full rear.

And bolt is not going fully into battery? Then you might have a short chamber as mentioned. Tried different ammo? Have you got another bolt you can try?

 

[Kansas_Born]

And bolt is not going fully into battery? Then you might have a short chamber as mentioned. Tried different ammo?

Bolt would not go into full battery with either method. At first I thought that I hadn’t torqued the barrel properly. I initially used a sandwich type system to hold the upper so I bought a reaction rod type to make sure everything was secure. The barrel but was torqued and was difficult to take off so that wasn’t the issue. I have not tried any other ammo. I have some prime 175’s on hand and maybe some federal 150 soft points. I can try those after reassembly.

 

[Mike_in_FL]

Bolt would not go into full battery with either method. At first I thought that I hadn’t torqued the barrel properly. I initially used a sandwich type system to hold the upper so I bought a reaction rod type to make sure everything was secure. The barrel but was torqued and was difficult to take off so that wasn’t the issue. I have not tried any other ammo. I have some prime 175’s on hand and maybe some federal 150 soft points. I can try those after reassembly.

Did you use anti-seize on the threads? Torque and release twice and stop on third time? How much torque?

 

[Kansas_Born]

Did you use anti-seize on the threads? Torque and release twice and stop on third time? How much torque?

I used anti seize and torqued to 40 ft/lbs. I know that I torqued and loosened more than once but can’t remember if it was twice of three times. I just reinstalled the barrel and will torque and loosen three times to see if it makes a difference.

 

[Kansas_Born]

Ok, with the rifle reassembled and the barrel torque I can get the bolt to lock into battery on a go gauge with a decent open hand pop to slam it all home with the upper out of the rifle. It’s a TIGHT fit and requires some work to get the bcg out of battery but it’s possible. This leaves me with the conclusion that it is a SUPER tight chamber but is not defective. I on the other hand might be. I’m wondering if my buffer spring/buffer needs to be heavier/strong since neither method to chamber a round was successful or if things just need to settle in.

 

[Kansas_Born]

Thank you @Mike_in_FL and @Waorani for your help!

 

[rpoL98]

Ok, with the rifle reassembled and the barrel torque I can get the bolt to lock into battery on a go gauge with a decent open hand pop to slam it all home with the upper out of the rifle. It’s a TIGHT fit and requires some work to get the bcg out of battery but it’s possible. This leaves me with the conclusion that it is a SUPER tight chamber but is not defective. I on the other hand might be. I’m wondering if my buffer spring/buffer needs to be heavier/strong since neither method to chamber a round was successful or if things just need to settle in.

my understanding is that it should not take a lot of pressure on the bolt with the GO-gauge to go into battery, finger pressure should be sufficient. regardless, whether the barrel is installed in the upper, or bare barrel and bolt. If you're applying force to get it into battery, then you're out of spec, your chamber is too short. Applying more force only runs the risk of damaging your gauge, or your chamber.

you could get a finishing chamber reamer (live-pilot), if it's not chrome-lined, and see if you just give it a few light spins (be generous with the cutting oil) to get the chamber into spec, constantly checking your progress. I had to do that once, maybe that's the bubba way, it worked. or send it to a gunsmith who will do the same.

if you have some other 308 bolts laying around, you could see if you get different (better) results with another bolt. I've had some luck sometimes with that also.

JMHO. YMMV.

 

[NukeMMC]

Are you stripping the bolt when checking with the GO gauge?

Check the brass on the FGMM you're trying to chamber. See if there are burnish marks where something is hanging up the round, especially at the neck/leade junction or the shoulder.

 

[Kansas_Born]

my understanding is that it should not take a lot of pressure on the bolt with the GO-gauge to go into battery, finger pressure should be sufficient. regardless, whether the barrel is installed in the upper, or bare barrel and bolt. If you're applying force to get it into battery, then you're out of spec, your chamber is too short. Applying more force only runs the risk of damaging your gauge, or your chamber.

you could get a finishing chamber reamer (live-pilot), if it's not chrome-lined, and see if you just give it a few light spins (be generous with the cutting oil) to get the chamber into spec, constantly checking your progress. I had to do that once, maybe that's the bubba way, it worked. or send it to a gunsmith who will do the same.

if you have some other 308 bolts laying around, you could see if you get different (better) results with another bolt. I've had some luck sometimes with that also.

JMHO. YMMV.

If it should only require light pressure I’m way past that. I’ll call Wilson in Monday and see what hey will do. I have no desire to modify the barrel, even if it will fix it.

 

[Kansas_Born]

Are you stripping the bolt when checking with the GO gauge?

Check the brass on the FGMM you're trying to chamber. See if there are burnish marks where something is hanging up the round, especially at the neck/leade junction or the shoulder.

The bolt was stripped for the hand check and I reinstalled the extractor for the full bcg test.

 

[Mike_in_FL]

you could get a finishing chamber reamer (live-pilot), if it's not chrome-lined, and see if you just give it a few light spins (be generous with the cutting oil) to get the chamber into spec, constantly checking your progress. I had to do that once, maybe that's the bubba way, it worked. or send it to a gunsmith who will do the same.

I think you're exactly right and that's probably how anybody would solve the problem. A handle on the reamer and a couple turns ought to do it. I think I had read somewhere that it shouldn't take more than 16 lb. to close (with a fully assembled bolt) because the weight reminded me of a bowling ball, lol.

OP, if you're going to send it into Wilson, send them your bolt. I'd have them hold the headspace no more than 1.632 and you'll have a good shooting rifle.

 

[padom]

It closes on a Go but wont chamber a live round? Did you mark the live round with black marker to see where the rub is?? Did you try any other ammo? If you load a mag, pull the CH all the way back and let go it wont chamber the round?

A good 100rds in a newly built large frame gasser is usually necessary to brake it in. If its closing on a go, but tight, I would go put 100 or so rounds in it, running it wet to break it in. I actually tested 2 of these barrels, they shot great and were very accurate.

 

[Kansas_Born]

It closes on a Go but wont chamber a live round? Did you mark the live round with black marker to see where the rub is?? Did you try any other ammo? If you load a mag, pull the CH all the way back and let go it wont chamber the round?

A good 100rds in a newly built large frame gasser is usually necessary to brake it in. If its closing on a go, but tight, I would go put 100 or so rounds in it, running it wet to break it in. I actually tested 2 of these barrels, they shot great and were very accurate.

It closes on a go with a pop with my hand on the end of the bcg (extractor in ejector and spring removed). I was unable to get the stripped bolt to rotate into the locked position with my hand on a go gauge.

Mag in charging handle back and release or drop the bolt with the release-neither option chambers a round.

I didn’t try any other ammo as the only 308 ammo I brought to the range on that day was the 168gr gmm. I’ll throw a marker in the range bag and a couple of other 308 ammo for the next trip.

 

[padom]

It closes on a go with a pop with my hand on the end of the bcg (extractor in ejector and spring removed). I was unable to get the stripped bolt to rotate into the locked position with my hand on a go gauge.

Mag in charging handle back and release or drop the bolt with the release-neither option chambers a round.

I didn’t try any other ammo as the only 308 ammo I brought to the range on that day was the 168gr gmm. I’ll throw a marker in the range bag and a couple of other 308 ammo for the next trip.

The smacking with your hand is most likely.the rough barrel.extension which is why putting 100 or so rounds in it to break.it in will help.

A GO is going to either close or not close...you hitting it with your hand isnt pushing the shoulder metal in the chamber to get it to fit...this isnt wood.

Would be very interesting to see where you're rubbing with a sharpie round...

 

[sinister]

Forcing the bolt closed on a gage may damage it. The gage and loaded rounds should fit finger tight (without the ejector).

A bolt carrier group requiring force to lock means each round is being force-fit and final-sized into the chamber -- maybe good for precision grouping/firing, but definitely detrimental to extraction and ejection. Should you feed a cartridge even a little bit dusty, or once there's a little fouling in your chamber you will have compromised extraction, ejection, feeding, and chambering as more energy is needed for cycling.

Your options include:

1) returning the barrel with your bolt to be done correctly;
2) swapping bolts for proper headspacing; or
3) getting a gunsmith to use a finishing reamer to get a proper fit.

Rounds should go in with finger pressure and fall out easily once you tilt the muzzle up, with gravity doing the work.

 

[__JR__]

do you know what your 'go' measures? Like is it 1.6300? a go can vary depending who's go it is.

 

[Kansas_Born]

The smacking with your hand is most likely.the rough barrel.extension which is why putting 100 or so rounds in it to break.it in will help.

A GO is going to either close or not close...you hitting it with your hand isnt pushing the shoulder metal in the chamber to get it to fit...this isnt wood.

Would be very interesting to see where you're rubbing with a sharpie round...

I just sharpies up a round and chambered it. The round chambered and the bolt rotated.
Pictures are acticing up so they will be attached at the end. It’s looks like the bullet is being shoved into the lands.

 

[Kansas_Born]

do you know what your 'go' measures? Like is it 1.6300? a go can vary depending who's go it is.

Go gauge is 1.630

 

[padom]

I just sharpies up a round and chambered it. The round chambered and the bolt rotated.
Pictures are acticing up so they will be attached at the end. It’s looks like the bullet is being shoved into the lands.

No that's not your lands, that's typical markings on a gasser round with an unpolished barrel extension. Those mark's are from the rough barrel extension when the bullet is stripped from the mag and pushed through the barrel extension before the tip of the bullet enters the chamber.

It chambered, bcg locked into battery. Go fire 100rd

You would have land marks down on the ogive of the bullet if the bullet was jamming into the lands...