Are gas tubes universal among ak-47s? will one size fit all?  Reason i ask, is i misplaced the gas tube (along with the upper hand guard attached).  It is a Lancaster Ak-47
there's two gas tubes listed on their website http://www.lancasterarms.com/ACCESSORY%20SELECT%20PAGE%20NEW.htm, but their website doesnt seem too friendly.  I'd rather buy from  a different source.

can i just buy any off the web?  If so can someone point me to a good source? how easy is it to attach a handguard?

It would depend on what variant of AK you got.  Here's a picture for AK-47s and AKM variants



Check if your gas block as vents holes. If it does, you need the one above (non-vented gas tube). If there are no holes, you need the vented one (2nd item on the picture. You must also note that gas tubes are actually hand fitted to the gas block and it's not exact - sometimes you'll get a gas tube that's too tight to fit and may need to file it down or too short and you get a loose gas tube.

To install a upper handguard, all you need is a pair of channel lock pliers. Clamp on the rear section (closest to the rear sight block) and twist the upper handguard on, rotating it 180 degrees until the bottom lines up.

I believe the standard is 7" give or take a mm(for most ak47/74)... I have an extra one pm if interested Ill shoot you... a pic, shoot you a pic....

http://www.robertrtg.com/akmgasblock.html
Dont know how to upload pics, but the gas block looks kinda like in the link...there are holes where the block entrance meets the tube . So i guess that is vented block, and i need an unvented tube.

it doesn't matter. the whole vented/unvented thing boils down to looks; buy the one you like the looks of. There is no functional difference.

I disagree. A non-vented gas block with a non-vented gas tube may cause more gas pressure build-up, potentially doing damage to the carrier and rear trunnion. You can probably get away with a vented gas block and a vented gas tube (as the Hungarians did).

Just curious, how in the hell do you lose the gas tube? Pick up the phone and get one from Lancaster. You'll need your serial number so they can match the hand guard. It'll possibly still require fitting. First, it may (should) be too long - you'll have to fit it by removing material from the front end. Then, you probably will have to trim the camming surface on the tube so the locking lever can be pushed down. Before filing on this part, first make sure the gas tube is fully seated - it must be parallel with the barrel, not higher at the rear - a properly fitted one will 'hang up', then snap into place. A loose one will just fall into place. Personally, I think maybe you should have it fitted by someone who knows what they're doing.

Many people have tested this theory and they all have proven it wrong. All the buildup of gas pressure is acted upon the face of the piston inside the gas block before the the weapon even begins to cycle. Anything more than that is simply excess gas and escapes around the piston. I've done the test myself using a non-vented GB and non-vented GT and experience no change in the behavior of the weapon.

IN Russia you dont even need the gun to shoot... you just squeeze the bullet really hard and hit the back with a nail...

The Russians, who developed and refined the AK platform, with over 60 years of AK building, who's AK design managed to keep those vent holes all these years - are wrong? And these "many people" you speak of somehow proved that vent holes are unnecessary? I hope Mikhail Kalashnikov is one of those people. Those countries that actually manufacture AKs decided to put those vent holes because they look nice?

Apparently. These are also the Russians (Mikhail included) who thought that a double hook trigger was necessary for many years. What happened to that? Let's look at the AK-100 series of rifles. They omitted the grooves in the gas piston, the holes in the gas blocks, AND the holes in the gas tubes. So I guess this MUST mean that all new AK-100 series rifles are falling apart due to "more gas pressure build-up, potentially doing damage to the carrier and rear trunnion"?

The vent holes were more than likely areas for debris to exit, and possibly even water. Seeing as pressure is reduced to near zero after the piston has left the inside of the gas block having holes for pressure reasons is pretty much pointless.

Perhaps. I'd still go by the tried and true with history to prove it. Innovation and change does happen. The change from double hook to single hook was more of the realization that the AK does not need no backup hook in case the other one broke, or perhaps a change in the metallurgy of the trigger that rendered the double hook obsolete.

Here are some AK-100 series pictures...

http://www.avtomats-in-action.com/parts7.html

Obsolete?

Does history prove that the reason that they had holes was for pressure reasons? The gas tube on an AK does not serve the same purpose as a gas tube on an AR. And yes, in earlier versions of the AK-100 type rifles there were holes in the gas block. Here's one that I picked up in October for my own 100 series build (and Saiga-12 build):

They decided a hammer retarder was more important to slow down the rate of fire in full auto when the solid AK 47 got cheapened out to the AKM. . Since there was no room, something had to go. Bye bye right hook. Many times when items are first designed, they are over engineered. Look at the Sig 220 series of guns. Originally, the hammers were milled, but to save money, Sig now casts the hammer. Will it work as long as the milled hammer. Probably not, but the cast hammer will probably last as long as the barrel. Companies are always looking to save cash, whether it means no grooves in the piston, or using cheap investment cast parts. A few bucks a gun isn't a whole lot, but when a company makes 100,000 units, it adds up. Years ago I remember when front brake caliper pistons changed from metal to plastic. From that day on we stopped using the factory Chrysler plastic pistons & started using aftermarket pistons that were still made from metal. I've been in many different industries in my life, & I can tell you newer is rarely better. My big dilema when a new product comes out is do I buy an early model, or should I wait until the bugs are worked out. But if I wait too long, the company will get cheap & start to use crappy parts to replace the good parts. I've seen this with guns, 2 way radios, & cars, & their replacement parts.  GARY  N4KVE

I agree, change isn't always the best thing. My only argument is the same one that gets brought up every now and again in the AK side of any forum, and that's that people think that the gas tube in an AK delivers gas to the weapon. Which it doesn't. So having holes or not will have no effect on the operation of the weapon.

Oh I agree on this point. It's not like the gas piston is a tight fit in the gas tube. Look at all the carbon half way down the gas piston. Plenty of blow by there to keep the pressure down.  GARY  N4KVE

Ok, so no holes on the gas block. That much I concede. There has to be some other way the extra gas is being released. I have a Saiga 12 2011 production and even with a fixed gas block and gas tube, it has a tiny vent hole on the left side of the gas block (not to mention the gas regulator).

2011 Saiga 12


2009 SGL 31


2009 Saiga 7.62x39

Just look at the above photo of the gas tube. The inner ridges rub against the gas piston head. The outer ridges allow the extra pressure to escape around the piston head.  GARY  N4KVE

OP- Try;

http://www.robertrtg.com/ak.html

or

https://www.apexgunparts.com/index.php/cPath/107


Both these vendors are GTG. Great prices, fast shipping and GREAT customer service.


Also, Yugo AKs utilize a longer than traditional gas tube so if your gun is not built from a Yugo kit then don't buy a Yugo gas tube.



CGP2 wrote; [regarding vent holes in the gas block or the tube] "There has to be some other way the extra gas is being released".

Look through the inside of any gas tube. It is not exactly a tight fit with the piston. Honestly, that thing looks like Jenna Jameson's butthole. The fact that you can still find lots of carbon and residue well beyond the length of travel of the piston head tells me that extra gas has no problem finding a path to equalize pressure.

https://www.apexgunparts.com/product_info.php/cPath/107/products_id/1933

experts on Lancaster AK-47 (i believe mine is NDS-3 model) - would the handguard/gas tube in the above link work?
i will call lancaster tomorow and see what their price is compared to the one above link. ideally i'd like to replace with the same russian red handguards, but if its way more than $30, i would buy from the above link

btw i took apart mine and hid the parts around my house before i went on vacation.  seems i hid it too well, I came back and could not find this one piece; i have no idea where i put it; i will tear apart the house again tommorow. worst possibility is that my mom inadvertantly threw it out as she was cleaning the house - she says she never seen it, but i dont know. if i cant find it tomorowo, i think i have to accept the fact that it is gone.

also this thread has taught me a lot about gas tubes.

Well, I couldn't sleep and perusing the forums as usual. There's a good discussion on the AK12 and saw something interesting on the rifles. I think most here have been sort of in consensus that a vent is not necessary, that there's plenty space behind the piston for the hot gas to bleed during recoil.

Here's the link to that discussion. Pay close attention to the photos. They are small but one detail is unmistakable - a vent in the gas block, on the AK-12 - the most bad ass new AK. I had to pull out the magnifier to be sure. The shiny piston kinda gives it away, even from a small picture.



I'm not an engineer so I can't claim anything with absolute certainly as to why these vents are ever present. One can surmise the that sheer heat of the gas blowing back towards the receiver can be great (perhaps too great) especially in full-auto and the vents acts as some form of compensator, as well as heat channels. Hot gas will find the shortest route to freedom - however little the holes may be. To sorta internet validate this thought, I scoured the internet and looked for videos of idiots doing full-auto mag dumps and noticed that those hot gases starts forcing themselves out of the joint between the gas tube and the gas block. With enough rounds (over 100), that area heats up so much handguards starts to light up. Can you imagine doing the same thing on a ventless gas tube/gas block, with all that hot gas going past the piston and into the receiver?

Just sayin...