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Curious if a gunsmith were to cut down a 16" barrel to 12.5" assuming the 16" was a mid length gas system would there be any issues w/ functionality / reliability?
 

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Curious if a gunsmith were to cut down a 16" barrel to 12.5" assuming the 16" was a mid length gas system would there be any issues w/ functionality / reliability?
Not unless the gas hole was already on the small or large size . If so a drill bit or gas block is all you need .

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You may have to open the port. If you go any shorter than 12.5 you may run into an issue with dwell time (the time the bullet passes gas port until it exits barrel).
 

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I don't know where you are but in my neck of the woods the gunsmiths stay busy with lucrative customs and charge accordingly. A fellow could buy a new barrel for what smiths would get for the lathe time to cut one down and rethread the muzzle, if they would even take on a little bothersome job like that.

No offense intended to you smiths out there; you get what you can get and that's called basic economics. My point is that, unless you're lucky enough to have the right kind of old school gunshop nearby, it might not be an economically practical idea to modify a 16" barrel instead of just buying a new 12".
 

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I don't know where you are but in my neck of the woods the gunsmiths stay busy with lucrative customs and charge accordingly. A fellow could buy a new barrel for what smiths would get for the lathe time to cut one down and rethread the muzzle, if they would even take on a little bothersome job like that.

No offense intended to you smiths out there; you get what you can get and that's called basic economics. My point is that, unless you're lucky enough to have the right kind of old school gunshop nearby, it might not be an economically practical idea to modify a 16" barrel instead of just buying a new 12".
ARP 12.5"

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I have cut down a few. It generally just requires opening the gas block to get it to cycle properly.
 

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Gas blocks are designed to restrict gas not amplify it . The size whole limits how much gas is available the orfice in the gas block limits how much of that gas gets to the tube/ bcg .

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Gas blocks are designed to restrict gas not amplify it . The size whole limits how much gas is available the orfice in the gas block limits how much of that gas gets to the tube/ bcg .

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I understand gas block restrict and not amplify. I have never measured or seen the gas port size listed on a barrel spec sheet. So would a arp 16” 6.8 mid length barrel have the same size gas port as arp 12.5 6.8 mid length. Never really thought about it until now so just curious.


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No, the shorter barrel has much less dwell time, meaning the time between the bullet passing the gas port and exiting the barrel. Once it exits the barrel all pressure is lost. Reduced dwell times means you need a larger opening to get enough gas back to the piston (bolt) in order for it to cycle.
 

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I realized he said open the gas block , what he meant was shorter barrel requires a larger hole for more pressure . No matter how much you open the adjustable gas block the port hole size determines the max gas available . The adjustment just limits gas .

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I realized he said open the gas block , what he meant was shorter barrel requires a larger hole for more pressure . No matter how much you open the adjustable gas block the port hole size determines the max gas available . The adjustment just limits gas .

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I fixed it. I meant to say open the gas port not the gas block. Now I understand the confusion.
 
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