I learned something new (to me) about the AR

[AOTAC]

Not a critique of the OP, but every video I've seen where the M4/AR was shot to failure it was the barrel that let go before the gas tube. Maybe I've just not seen enough video of these kinds of things.

I was under the impression that the gas tube was intended to pop before the barrel melted down. I'm sure there are people that know a lot more about the subject that can correct me if that's wrong.

[lysander]

I was under the impression that the gas tube was intended to pop before the barrel melted down. I'm sure there are people that know a lot more about the subject that can correct me if that's wrong.

Actually, no.

With the lightweight M16 or M4 barrel (~3/4 to 5/8" diam under the handguards) the barrel will rupture before the gas tube in sustained full automatic fire. It takes around 3 minutes/500 to 600 rounds.

[okie]

CLARIFICATION: Dwell time is from ignition to the beginning of unlocking.



Every text book on automatic weapons design written since the 1930s . . .

But, here's just one example from a 1954 report:

Right on. That just never did sound right to me, and now I know why!

[prepare]

Actually, no.

With the lightweight M16 or M4 barrel (~3/4 to 5/8" diam under the handguards) the barrel will rupture before the gas tube in sustained full automatic fire. It takes around 3 minutes/500 to 600 rounds.

What about the current M4 profile barrels?

[gaijin]

I saw a post years back by a newb saying that he knows the gas tube is the single most important part on the M4; so how often should he clean it. That got my mind into thinking about the mechanics and I realized back then what the op is saying.

I would just make sure the gas block is removed or something is in the gas tube hole of the gas block so fire does not come back towards the shooters face.

Lastly I came to my own conclusion that the gas tube is certainly NOT the single most important part. You need a barrel before anything else. Think about it, you could jam a round into a bare barrel and set it off with a hammer and a nail. Shoot, just rock and a nail.

Just be prepared to eat that rock and nail.

[Warp]

lol yeah with nothing behind the round the bullet might not go anywhere, if there's space for enough pressure to exit the breech. After all, if a loose round gets cooked off by fire or whatever, the bullet doesn't really move because it's far too heavy compared to everything else and pressure takes the path of least resistance

[prepare]

Actually, no.

With the lightweight M16 or M4 barrel (~3/4 to 5/8" diam under the handguards) the barrel will rupture before the gas tube in sustained full automatic fire. It takes around 3 minutes/500 to 600 rounds.

This was not by design was it?

[lysander]

What about the current M4 profile barrels?

Do you mean the heavy SOCOM?



That profile was designed to increase the full automatic endurance, it turned out that this size over-heats the gas tube first. It wasn't intentional.

[Barrel failure first] was not by design was it?

No, they just made a barrel that was lightweight. No one really cared back then if the barrel ruptured after 600 rounds of full automatic fire, because they figured no soldier carried 600 rounds and would shoot them all in one go.

[prepare]

Do you mean the heavy SOCOM?



That profile was designed to increase the full automatic endurance, it turned out that this size over-heats the gas tube first. It wasn't intentional.


No, they just made a barrel that was lightweight. No one really cared back then if the barrel ruptured after 600 rounds of full automatic fire, because they figured no soldier carried 600 rounds and would shoot them all in one go.

Thanks for the clarification.

[tehpwnag3]

Yeah, shooters who use AGB's know all too well what happens when the gas is shut off (or very close to being).