I recently purchased two 16 inch AR15 barrels for two new builds at a gun show. One is a light weight and the other is a heavy weight barrel. The vendor did not have any gas tubes. I need help determining what length gas tubes I need. The front sight is farther forward on the heavy barrel than it is on the light weight barrel.
The distance from the rear of the front sight to the rear of the light weight barrel is 7 7/8 inches.
The distance from the rear of the front sight to the rear of the heavy weight barrel is 10 inches.
These measurements could be off more or less a fraction of an inch.
I don't have a Photobucket account or any other way to post photos of the barrels.

From the description is sounds like one is Carbine length and the other is mid length.

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Thanks for the information and picture. I bought them online today.