Quote History Quoted:
Wasn't a piston. It was a modified DI where the gas tube was attached to the carrier and functioned as the action rod. The concept still reduced gas blowback.
I think the companies selling them had a lot to do with their demise. They always seemed to be interested in LE sales and not much interest in civilian sale. I tried a few times over the years to get them to sell me a short barreled upper for a pistol, but they flat refused each time.
Also, as far as ARs go, this was one of the least modular.
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Respectfully, we could banter semantics about what type of system it is, but it does use a gas piston/operating rod, just an earlier (than most of the current AR piston designs) and slightly different (hybrid?) version that the inventor chose to call a "delayed gas impingement" system. The long "gas tube" that is bolted to the top of the bolt carrier, where the gas key would normally attach, is actually a really long operating/push rod. I personally think that it's a cool design regardless...YMMV.
Here are a couple of good links about the gun, and the actual operation of the system:
http://www.m4carbine.net/showthread.php?61086-Para-TTR-ZM-LR300-requesting-pics-and-opinions
http://www.weaponeer.net/forum/forum_posts.asp?TID=11144&PN=1
And here is a link to an older thread from here in the hive:
http://www.ar15.com/forums/t_3_118/507832_PARA_TTR___ZM_WEAPONS_LR300_what_do_you_guys_think_of_it___.html
The link below has some interesting info, straight from the designer, and some discussion from Todd Jarrett as well. The old Para videos of Todd Jarrett shooting it and demonstrating its almost complete lack of recoil were very cool, if you can still find them somewhere.
http://www.tactical-life.com/gear/para-usa-tactical-target-rifle-556mm/
And here is another "interesting" link...
http://avtomat-pistolet.com/z-m-weapons-lr-300-para-usa-ttr/
And the obligatory Wikipedia link, with excerpt below:
http://en.wikipedia.org/wiki/LR-300
"The gas key is extended beyond its normal length to form an operation rod, such as an M14 or AK47, extending into the top of the forward handguard. The gas key contains the return spring which is fixed between the front of the receiver and the collar at the front of the gas key. The gas tube runs backwards from the gas block in the front sight base and enters the gas key. In this way when the firearm fires at least some of the combustion gases from inside the gas tube are vented into the handguard area rather than the receiver. This means the standard buffer assembly is not required at the rear of the weapon, allowing a folding stock to be fitted to reduce the overall length of the weapon."