AK47 vs AK74 gas tube

I'm not to well versed in different varieties and or models of AKs but can anyone tell me the difference of the tubes if there is any?

The AK74 (except Romanian) gas tube includes a an anti-rattle flat spring. This adds to the gap (or subtracts from it) at the rear sight end. Some newer ones (AK74M) may have a slightly different angle or fit where the lock latch turns in to the end of the tube to retain it.

I am in the middle of a saiga 308 conversion and was told that I needed a AK74 gas tube to do a wood handguard. The flat spring that you speak of must be something that is similar to the one on my 308.

Is there any difference in length or diameter?

The flat spring is the same as the Saiga and the tube should be made for it rather than using an AKM tube and trying to fit a spring which likely won't fit. The Saiga has the newer cut in the retainer lever and tube. This is a separate issue from the spring. Some reshaping with a file on the AK74 tube may be required to lock the lever down. It's very light. If the tube i too long, file straight across the front of the tube until it seat. Even after it seats the lever my not rotate all the way to lock. This is where the rear edge of the gas tube need some slight file work. The AK74 tube might fit without any fitting if you are lucky or it might be a slightly loose fit.

Yeah I was told that there would be some filing involved, thats no problem would really like to get away from the polycrap look and get back that classic AK look.

Thanks for info, allesennogwat

the front of an AK gas tube is not true. There is a bevel on the top of the tube. When fitted and not cammed, the bottom should have a 0.3mm gap min, the top 1.5mm max.

Shorter tubes such as on the pistol builds require a more aggressive bevel, If the bevel isn't there, then when the tube has been shortened enough to fit, it will be too short for the camming action to lock it forward and down. Now you can fix that by welding up the top rear camming surface and recutting it, but it sure is easier to kiss the top front to a belt sander than to weld and refit later. loose. '74s also have a more aggressive bevel on the bottom rear wedge.

I fitted the anti-rattle spring to a Romy tube - not a big deal really - just a mill cut top and bottom It doesn't fit exactly the same as the '74 but works the same way.

Now all I need to do is find a "74" gas tube!

I looked in the Soviet repair manual for the AKM and it shows the front of the gas tube straight up and down on the bottom half with the top front half angling back leaving a gap of 1.5 mm between the top of the gas tube and gas block. The amount of angle is not shown. The rear of the gas tube has a 30 degree angle where the retainer turns in to the gas tube. This is for early AK's, so later ones may be slightly different.

In the newer AK74 repair manual it shows the rear gas tube angle still at 30 degrees but may or may not be longer or deeper. It shows the flat spring and the big difference is the front top gap is 1.9 mm between the gas tube and the gas block. The bottom front half of the gas tube is straight up and down with the top half angling back 1.9 mm at the top edge.