Were these a standard part on any guns that made it over? Seems like a decent idea to keep heat from building up.

Its an after market item...never ever used on military AKs from any country.

It's been my experience that it's difficult to generalize when it come to Chinese manufactured rifles brought into the USA.  To my knowledge, no pre 7/1989 rifles used the ventilated steel handguard / gas tube combination.  I don't know about the rifles brought in after that.  Just for grins, I purchased one of the ventilated handguard / gas tube assemblies form Polytech Parts and, with some fitting, installed it on my Polytech Legend.  The tube does not have gas venting holes.  I'm still evaluating the impact on function, fouling, etc.  Here is a photo:

Is it possible that the chinese use it on more recent rifles?

NO....ITS A US MADE AFTER MARKET ITEM.....AGAIN......IT HAS NEVER BEEN A PART ON ANY MILITARY AK IN THE WORLD........ITS NOT CHINESE.......ITS US...FACE IT...ITS NOT MILITARY. You can make up any scenerio you want.....it is what it is whether or not you believe it or not. THERE ARE NO RECENT CHINESE RIFLES.......THE LAST ONES IMPORTED WERE IN 1994.

Quoted: NO....ITS A US MADE AFTER MARKET ITEM.....AGAIN......IT HAS NEVER BEEN A PART ON ANY MILITARY AK IN THE WORLD........ITS NOT CHINESE.......ITS US...FACE IT...ITS NOT MILITARY. You can make up any scenerio you want.....it is what it is whether or not you believe it or not. THERE ARE NO RECENT CHINESE RIFLES.......THE LAST ONES IMPORTED WERE IN 1994.

Hey Easy killer. The reason I was so curious about is that I found it at polytechparts.com ... you'll see that they have little or no US parts and the rest is pretty authentic.

There are millions of recent chinese rifles and innovations. They simply aren't importing them.

In addition, there are very few resources to find info on what is being recently produced. I have looked around and just can't find any recent photos of chinese rifles.

I am probably wrong on this. But to say that nothing has changed in china after 1994 is pretty naive to.

Several nations' military R&D programs have tried using steel (or other material) ventilated coverings (hand guards) to cover the gas tubes but, to my knowedge, none resulted in any production (military or commercial) AK rifle variants.  I think it was largely decided that the use of synthetic materials with, in some cases, heat shields was preferable to other styles of hand guards.

With that said... I kinda like the ventilated handguard / piston tube arrangement if, for nothing else, it's strentgh and durability.  I haven't had much luck with the chu (spelling?) wood found on many Chinese rifles.  The chu wood is comparatively delicate and splits easily.  The grain isn't very dense and is oriented parallel to the gas piston tube's axis (rather than cross grain) making the handguard's strength suspect.

So far, my "legend" seems to like the ventilated handguard / gas tube assembly.  There aren't any issues with extraction, and ejection of spent brass is very consistent.  I can't tell any real difference in function or fouling or feel of the rifle using the aftermarket tube compared to the OEM tube with one exception.  The steel ventilated covering does get rather warm after a couple hundred rounds.  Since it's connected directly to the gas tube, that's no surprise.  I'm guessing that's one of the reasons it's never been applied to a commercial or military rifle.