Converting a carbine barrel to mid length

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beavis_m305

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Hey guys,

Got given an AR barrel with a mis-aligned gas port. I was wondering if it would be feasible to weld or plug the gas port somehow and have it re-drilled at mid length.
Any thoughts appreciated.

Cheers, Beavis
 
beavis_m305 said:
Hey guys,

Got given an AR barrel with a mis-aligned gas port. I was wondering if it would be feasible to weld or plug the gas port somehow and have it re-drilled at mid length.
Any thoughts appreciated.

Cheers, Beavis
Click to expand...

The first thought that comes to mind is you should take a close look at the barrel in question and the answer to your question will quickly become blindingly obvious.

Hint: The OD in front of the gas block is too small to accept a gas block.
 
Suputin said:
The first thought that comes to mind is you should take a close look at the barrel in question and the answer to your question will quickly become blindingly obvious.

Hint: The OD in front of the gas block is too small to accept a gas block.
Click to expand...

? Ok to be clear, the profile is .75" from where the gas port is to the start of the thread. It's carbine gas on a 14.5" tube, so there is 7 or so inches of barrel ahead.
 
The existing port could be tapped and a plug installed. A new port could be drilled for a mid-length setup. The gas block would need to fit tightly on the barrel.
I have installed a sleeve on a barrrel which was smaller than a gas block. Works fine.
If the existing gas port is so misplaced that the barrel is unusable, go for it. But if the gas port is only misplaced a bit, why bother?
 
tiriaq said:
The existing port could be tapped and a plug installed. A new port could be drilled for a mid-length setup. The gas block would need to fit tightly on the barrel.
I have installed a sleeve on a barrrel which was smaller than a gas block. Works fine.
If the existing gas port is so misplaced that the barrel is unusable, go for it. But if the gas port is only misplaced a bit, why bother?
Click to expand...

Yah, lo pro gas block and quad rail equals problem solved.
 
Are the gas ports that F'd up that they just cannot be used with a low pro block?

What about using one of those not so common pig tail gas tubes?
 
Pretty sure the extension is on tight, but I will check. My concern was that the port might be too far gone to function, I'm trying to find out if the rifle it was on would cycle.
 
beavis_m305 said:
? Ok to be clear, the profile is .75" from where the gas port is to the start of the thread. It's carbine gas on a 14.5" tube, so there is 7 or so inches of barrel ahead.
Click to expand...

Are you certain? The gas block area should be a precise 0.750" fit, while the barrel out to the muzzle is often 0.010"-0.020" smaller to make it easy to slide the gas block on up to the fit at the port.


Mark
 
mmattockx said:
Are you certain? The gas block area should be a precise 0.750" fit, while the barrel out to the muzzle is often 0.010"-0.020" smaller to make it easy to slide the gas block on up to the fit at the port.


Mark
Click to expand...

I'll bust out the calipers tonight and check that as well then. I have a spare JP .75 block that is super tight all the way to the gas port. You might be right I'll have to check. It's no big deal really, the barrel was given to me for nothing. Worst comes to worst I'll just plug the gas port and use it with a .22lr conversion.
 
mmattockx said:
Are you certain? The gas block area should be a precise 0.750" fit, while the barrel out to the muzzle is often 0.010"-0.020" smaller to make it easy to slide the gas block on up to the fit at the port.


Mark
Click to expand...

This is correct. Typically the OD in front of the barrel is .730" or so which is way to small to fit a gas block. Even if the gas block did fit properly there would be no shoulder behind it to hold it in place against the recoil forces.
 
I think the solution was staring straight at me actually. If I was to get the gas port drilled in the correct position and the old one maybe plugged up somehow, it should work fine?
 
Suputin said:
This is correct. Typically the OD in front of the barrel is .730" or so which is way to small to fit a gas block. Even if the gas block did fit properly there would be no shoulder behind it to hold it in place against the recoil forces.
Click to expand...

I hadn't thought of that
 
beavis_m305 said:
I think the solution was staring straight at me actually. If I was to get the gas port drilled in the correct position and the old one maybe plugged up somehow, it should work fine?
Click to expand...

How far off is the port? It could be plugged and there would be enough room for another port?
 
tiriaq said:
How far off is the port? It could be plugged and there would be enough room for another port?
Click to expand...

I think so yea. If I line the gas block up with the port, it is about 30 degrees off center. Apparently the rifle it was on would cycle but it looked really ugly, the gas tube must of had a good amount of pressure on it.
 
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