PRI Fat Boy gas tube?

[*Paladin*]

I bought one several years ago and used it on a 14.5" gun. When using hotter milspec ammunition it ran fine. In fact it felt softer to me under recoil than previously.

As soon as I ran of out that ammo during that time frame and picked up some generic stuff from wal mart the gun immediately turned into a single shot rifle.

So, at least if you're not running hotter ammunition, I'd say it's a don't purchase item to anyone considering one.

Thanks! That's what I was looking for! So far, everything else I've read about it elsewhere said basically if the barrel isn't 12.5" or shorter it could cause some reliability issues. And the posts I read pretty much ran the gamut of "it's the greatest thing since sliced bread" to "avoid at all costs". I just wanted to know if anyone had first-hand experience with it and could share that with me. I'll start off running the standard gas tube with a H-buffer and see how it runs and work from there. Much appreciated!

[JoshNC]

I tried one on a very well used Colt M4 barrel that was way over gassed and subjectively it really didn't do much. This was on a transferable Colt M16 lower with H-buffer. I sold the upper long before I ever knew about H2, H3, etc buffers. Think MAC speed on fullauto with either the standard or PRI fat boy.

I agree with markm, I would address gas port size IF being over gassed is an issue.

[Clint]

All of this stuff was computer modeled 40 years ago by the Army.

According to that reasearch, Increasing Initial gas system volume (by the fat tube) has a very weak affect on bolt carrier speed.

Unsurprisingly, gas port diameter has a very strong effect.

If the current barrel is overgassed and you need to make it work, just insert the proper size port like markm did.

[eodinert]

It doesn't seem to me like a larger diameter gas tube would have any effect at all on volume, because the gas port would determine that.

Just gaming in my head what a larger diameter gas tube might do, it seems like it might fake 'duration', by not passing the gas impulse as quickly to the bolt carrier... but that is speculative on my part.

Do it... and tell us what happens :-).

[markm]

If the current barrel is overgassed and you need to make it work, just insert the proper size port like markm did.

That's what I was getting at. If you're keeping the Standard FSB, you can throttle down that gas to .070 or something and have a decent running shorty.

[munch520]

That's what I was getting at. If you're keeping the Standard FSB, you can throttle down that gas to .070 or something and have a decent running shorty.

Maybe I missed it in your other thread, how hard/tedious was installation?

Paladin, we're blindly throwing darts at the board since you don't know port size yet. My barrels .5" longer and with a much smaller port, but the A5H4 has tamed mine down while suppressed...the heavier buffer and a LMT-E carrier might help mitigate any issues on your 11.5"? I'd think those would have a more meaningful impact than a fat boy, pigtail, etc. gas tube.

[markm]

Maybe I missed it in your other thread, how hard/tedious was installation?

I guess that's relative. You have to remove the FSB. In my opinion, if you can handle that, the rest is basic stuff.

[munch520]

Even I can manage that

[thehun]

I wouldnt even bother with building a DPMS barrel

As others have said...gas port is what really matters...just like iraqgunz said..call ADCO

Unfortunately you probably going to end up spending as much on that DPMS barrel as you would have BCM, Rainier, DD or Noveske

[308sako]

I seem to remember an equation about the Pressure Volume and Temperature relationships. That said the Fatboy MUST have some affect on the system.

Yes the port size is primary... I get that.