AR 15 barrel swap

N

newmexkid

New member
So, my grandson wants a different barrel for his AR. I should have all the tools, (this weekend) I need to do the swap and have been watching You Tube videos on the process. The only part the puzzles me is the headspace. I have watched videos on how to check it with go/no go gauges and how guys do it without the gauges. However, They all say that the headspace must be checked on a new barrel but...None say what to do if the headspace isn't correct. Seeing as this will be the first AR I work on, to say that I'm confused is not the halve of it!! So, any help on how I can do this correctly? Thanks. Thought I'll do his first before I try it on mine
 
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If it isnt correct, you will need another bolt to check it with.
Ive assembled several AR15s and AR10s. Never had one out of headspace yet.
I check them with a live round with the rifle pointed in a safe direction.
 
Originally Posted By: NonnieselmanIf it isnt correct, you will need another bolt to check it with.
Ive assembled several AR15s and AR10s. Never had one out of headspace yet.
I check them with a live round with the rifle pointed in a safe direction.

So, are you saying you just install the new barrel, make sure a round chamber properly and touch her off?
 
Originally Posted By: newmexkidOriginally Posted By: NonnieselmanIf it isnt correct, you will need another bolt to check it with.
Ive assembled several AR15s and AR10s. Never had one out of headspace yet.
I check them with a live round with the rifle pointed in a safe direction.

So, are you saying you just install the new barrel, make sure a round chamber properly and touch her off?

I've got four dozen uppers setting here. None have ever seen a head space gauge. I still have all my fingers and toes and have never had one that mic'd out of spec based on fired cases when used with an in-spec bolt. I had a long 6 PPC but the bolt was about 0.017 too deep!! BTW it shot fine anyway.

Greg
 
If the headspace is wrong, there's not much that can be done without major rework to the barrel assembly.

Originally Posted By: newmexkid,So, are you saying you just install the new barrel, make sure a round chamber properly and touch her off?

That's it. Check the fit of a factory round with thumb pressure and no action spring. If the fit feels tight, stop and investigate. If the round fits without a lot of thumb pressure, reassemble the rifle and test fire.
 
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The beauty of the AR Stoner design is that it is made to be easily field repaired. The specs required any bolt to headspace on any barrel then there would not be need to machine anything for a proper repair or replacement of a bolt or barrel. As long as the mfg follows military specs they should all headspace. The only time I would worry is if you got a cheap Chinese product.
 
Originally Posted By: GLShooterOriginally Posted By: newmexkidOriginally Posted By: NonnieselmanIf it isnt correct, you will need another bolt to check it with.
Ive assembled several AR15s and AR10s. Never had one out of headspace yet.
I check them with a live round with the rifle pointed in a safe direction.

So, are you saying you just install the new barrel, make sure a round chamber properly and touch her off?



I've got four dozen uppers setting here. None have ever seen a head space gauge. I still have all my fingers and toes and have never had one that mic'd out of spec based on fired cases when used with an in-spec bolt. I had a long 6 PPC but the bolt was about 0.017 too deep!! BTW it shot fine anyway.

Greg

To tag onto what what Greg was saying here, if you have a top quality barrel manufacturer, you are probably not going to run into problems. As Greg said, sometimes there is a lot of allowable variances that will still allow the rifle to be safely used. When we try a new barrel manufacturer we will check with a go-no-go gauge to see if they are within the tolerances. We saw problems with the 6.5 Grendel in the early days of it's life, when people were mismatching bolts to chamber prints. If you do not want to go with the go-no-go gauge you can use the poor mans gauge. Strip down your bolt, pulling your extractor and ejector out of it. Drop in a live round and see how much effort it takes to close and rotate the bolt. There should be some resistance and the bolt should lock up snug, no rattle. if you cannot get the bolt closed, the chamber is too shallow. If the bolt rattles and wiggles, then the chamber is probably too deep. Either condition should be taken to a gunsmith so that the chamber can be accurately measured. I have gotten barrels from some companies that were chambered too deep and the rounds would get pushed forward by the firing pin and would not ignite causing a fail to fire condition. These problems tend to be a little more prevalent in the non-mil-spec calibers. We don't really see problems like headspacing too often these days.
 
Well, as this rifle will be just a plinker/coyotes down the road, I decided to just order a barrel from EABCO. Got the barrel, gas block, gas tube and hand guard all together. Still don't have a clear picture in my head as to the installation point of the gas plug. I had one thought...Install the tube through the barrel nut until it stops and then slide the gas plug forward until the tube stops and tighten everything up?! Then I thought, can't be that simple. Hoping I can do everything myself as I'm spread a little thin with currently having another rifle built and 2 sitting in the safe waiting for scopes. It's addictive!!
 
Gas plug?

The gas tube fits in the gas block. Slide it into the gas block until the roll pin can be driven into place to hold the tube. The back of the gas tube fits through the barrel nut & upper. There should be a little play where it fits through the barrel nut & upper. Be sure to get the right length gas tube for the gas system, carbine, middy or rifle.
 
Originally Posted By: MistWolfGas plug?

The gas tube fits in the gas block. Slide it into the gas block until the roll pin can be driven into place to hold the tube. The back of the gas tube fits through the barrel nut & upper. There should be a little play where it fits through the barrel nut & upper. Be sure to get the right length gas tube for the gas system, carbine, middy or rifle.

That's exactly what I needed to know. Thanks.
 
That all being said the GB is usually about 0.030 off the barrel shoulder when properly aligned with the gas port. If your barrel is dimpled that will line up with the gas block rear screw and it will be far easier to align.

Greg
 
I've swapped at least a dozen barrels on my AR's and have never checked the headspace nor have I ever had an issue with headspace. If you go with a well known, reputable barrel maker you won't have any issues. Mount it and shoot it.
 
Originally Posted By: MistWolfIf the headspace is wrong, there's not much that can be done without major rework to the barrel assembly.

Originally Posted By: newmexkid,So, are you saying you just install the new barrel, make sure a round chamber properly and touch her off?

That's it. Check the fit of a factory round with thumb pressure and no action spring. If the fit feels tight, stop and investigate. If the round fits without a lot of thumb pressure, reassemble the rifle and test fire.

MistWolf - how will inserting a round in the chamber by hand let you determine if the bolt will close properly?
 
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