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2/13/2005 12:28:56 PM EDT
I'm looking to get an AR-style rifle soon. I prefer a shorter barrel, but my 50 yr. old eyes demand the full length sight radius. I have looked at a few pre-owned Bushmaster Dissipators and like them. But I have been told that the older Dissipators which have the gas bolck closer toward the receiver are to be avoided, as they are less reliable. It was recommended to look for one that has the block almost at the front sight.

Not knowing very much about  AR's yet I thought I would pose this question to y'all. Is there a reliability issue with the earlier Dissipators with the shorter gas tube/block assembly? How do I actually tell the difference? Should I avoid these, or is it much ado about nothing? Is there a relatively inexpensive correction/cure for this? Thank you for your help.
2/13/2005 12:41:08 PM EDT
[#1]
From what I understand, a "Dissipator" is a 16 inch barrelled rifle, with a carbine gas system, and a front sight base set rifle length distance from the rear sight. No gas port on the front sight base.

There should be no difference in reliability from any other 16 ich carbine with a carbine length gas system.  

Tapping the gas from the FSB, instead of the hidden block under the guards, would be no different than taking a standard 20 inch barrel and cutting it back to 16 inches. This DOES cause some reliability problems, and the gas port diameter will probably need adjustment.

IF you're wanting the full length sight radius of a 20 inch barrel, in a 16 inch barrel, with the best reliability, you might try building one in a mid length gas system. While all three methods can be made to work, I understand the midlength gas system is the most reliable in a 16 inch barrel.



Lonny
2/13/2005 3:25:12 PM EDT
[#2]
+1 for the above, but I'd add:


Quoted:
I'm looking to get an AR-style rifle soon. I prefer a shorter barrel, but my 50 yr. old eyes demand the full length sight radius. I have looked at a few pre-owned Bushmaster Dissipators and like them. But I have been told that the older Dissipators which have the gas bolck closer toward the receiver are to be avoided, as they are less reliable.  -Not true, these are just CAR length gas systems, millions of them out there!

It was recommended to look for one that has the block almost at the front sight. - Called a mid-length gas system and some will say it's a bit smoother (but much less common)

Not knowing very much about  AR's yet I thought I would pose this question to y'all. Is there a reliability issue with the earlier Dissipators with the shorter gas tube/block assembly? -NO

How do I actually tell the difference? - A CAR gas system has the gas port (and hence the gas block) ~7.5" from the chamber.  A mid-length system has the gas port ~9.5 from the chamber.

Should I avoid these, or is it much ado about nothing? - Buy which ever you can find.

Is there a relatively inexpensive correction/cure for this? - Send your money to me before the BRD takes hold of you!

Thank you for your help.

AR Sponsor