SOT Question: M16 Barrel Length and Form 4s

Does it matter to the ATF if the upper currently on a registered M16 lower is a different length than what's listed on the form? When buying or selling an M16, do you make sure the barrel length and F4 or F3 match? Basically I want to know if I should have an upper with the appropriate barrel length available should I ever go to sell the gun. Thanks in advance.

I think it is. I remember(IIRC) my dealer stating I had to mark down the correct length barrel length
even though it was a full-auto. I could be wrong, it was some time ago.

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Originally Posted by bogey1

I think it is. I remember(IIRC) my dealer stating I had to mark down the correct length barrel length
even though it was a full-auto. I could be wrong, it was some time ago.

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Thanks Bogey. Guess the best option is to make sure an upper of the correct length is with it. Cheap enough, all things considered.