Gas piston wobble?

Is it normal to have some play/wobble between the gas piston and the bolt carrier? Or should it feel as if the entire assembly is 1 piece of metal, with no play between the 2?

Wobble = sex.

yes, there is supposed to be wobble. Up to 4mm lateral on an AKM. It helps the piston find the gas block - which given how violently the bolt carrier and receiver are moving on 3 axis, is a good thing. Thats one of the reasons the Century Builds are problematic - by welding the gas tube instead of setting the correct gap between the bolt carrier and the gas piston shoulder, and then riveting it with the piston hole larger than the rivet, there is no wiggle and the piston bashes into the side of the block.

AK100 series are fixed

Interesting. My first Lancaster RR had no wobble where the gas piston connects with the bolt carrier.. My second did wobble.

My new In Range ak74 has no wobble; it feels like the piston and the bolt carrier are 1 solid piece...

Should I be concerned?

The guns are not built to original factory spec. With the Lancaster, what do you expect you buy "cheapest" from a pathological liar like Chet. He just doesn't give a damn. I don't know about the other.

Just drive the rivet out (it is riveted right? tell me they didn't weld it like the drunken monkeys at Century?) slightly enlarge the hole in the Piston if its the same size as the carrier, and maybe run a tight M12 die over the piston. Then screw it back in and re-rivet.

Most common cause of a seized piston in a riveted carrier is skipping the step where you unscrew after drilling, and blow out the metal shavings, and then open the hole in the piston more than the carrier. Otherwise, the metal shaving will bind, or the rivet will expand inside the piston and lock it in place.

Oh - and there are also those that screw the piston all the way down. wrong answer. Spec is a gap between the two - usually 1/4 turn will do it.

I have an AK 100 in the shop with the dimple retainer - I don't know about that. There were several other changes on the AK100 a well, which may have eliminated the need for wobble.

Well, with the lancaster, It was my first AK and I didn't know what to expect :) With the second lancaster, the wobble was present - thus this thread. However, the lancaster rifles had other serious problems in the form of the rear trunion being hammered by the bolt carrier until the rivets holding in the trunion bent badly, dust cover wouldn't stay on.

Now i'm on my third rifle in a row, just trying to get a good AK74. This time I went with In Range, after reading many positive reviews of In Range's work. Now on my third rifle i'm being told that it was built incorrectly too. FOR FUCK SAKE CAN'T ANYONE JUST BUILD THE FUCKING RIFLE THE CORRECT WAY?

Sorry, just had to get that off my chest.

I can't see how the gas piston is attached to the bolt carrier; externally, it seems like there isn't anything visible like a rivet; I assumed that the bolt carrier and piston were threaded and simply screwed together. Is there supposed to be an externally visible rivet, or is there something only accessible on the inside of the bolt carrier?

Edit: OK, I think I see a rivet; the finish has basically covered it over. It doesn't look like the rivets on the receiver that are mushroomed out; this one looks like maybe it was sanded flush with the bolt carrier.
I've never set or removed a rivet, and while I do have a set of dies, i've almost no experience using them. How would you enlarge the hole in the bolt carrier? How would you remove the rivet? it looks like it's only accessible from one side of the bolt carrier; would it need to be drilled out?

I don't have a machine shop. If I did, i think i'd have said fuck this and converted a saiga a long time ago.
I guess this rifle will also be sent back to atlantic if this isn't something I can deal with; is this issue one that is serious enough that the rifle should be returned for repairs? After seeing this video:
http://www.youtube.com/watch?v=S0hnyTzE2cw&feature=related

I'm 99.5% sure i can't go through those steps...no drill press here, i don't have rivets, no sanding other than my dremel...overall I think i'd make a fuck-up of this process. There IS a gap between the piston and the carrier...but no wobble.

take a short, stubby punch - any longer than 1/4" and it will likely break (thus leaving you with a shorter one!) Give the center of the rivet on one side a good wallop with a hammer and punch. This should displace it enough that you can more clearly see it - as you noticed, they are ground flush.

Once the rivet has flared inward, you'll have a little cup to center a drill bit - drill out the head. Sise isn't that important, as long as its smaller than the countersink around the hole in the carreier the rivet goes through. Once you've drilled it so the remnants of the head are paper thin, you should be able to just punch it the rest of the way through - start again with your stubby punch, then move to a longer one. I use an air hammer, but only for speed.


I also use an air hammer for reinstall - but you can do it with a regular hammer - lots of light hits form better than a lesser amount of big smacks.

http://www.arizonaresponsesystems.com/notes/notesak/ak47build/pageak47build.shtml#anchor7

Does you rifle function correctly?

You didn't mention anything it wasn't doing right so I assume you are trying to fix something on a rifle that works just fine?

I'm just checking.

Some people like to have their rifles meet the designer's specifications. Just because the out-of-spec part hasn't caused a failure is no reason not to correct it.

I hadn't taken the rifle out and shot it yet when I posted this, actually, so I didn't know if it would affect the reliability of the rifle. After my other 2 shoddy POS ak74's shot themselves to pieces in a few hundred rounds, I was simply checking to see what the correct way would be for this part to fit, after doing a careful inspection of the weapon.

I've taken it out to the range since, and it broke something free in that joint because now there is an ever so slight bit of wobble. Less than 1mm....probably less than 0.5mm.

I appreciate the information, Gunplumber. Don't pay attention to the peanut gallery. It's like someone saying, 'why did you buy a car and then complain when there is no spare tire in the one that is delivered?'...well, maybe I want back seats in my car. "But the car works just fine"...well, yeah. I guess it does, but I still want back seats because that's the spec I paid for and that's the spec I should have been delivered; the car was supposed to have a spare tire and so it should have it. Just like the rifle should have gas piston wobble, it would appear.

However, i've put ~800 rounds through the rifle and everything appears to be wearing normally - no strange excessive wear anywhere - and the action is quite smooth, generally; I think i'll let it ride for now, since it HAS developed a bit of wobble like it should have - though honestly, if I was confident in my mechanical abilities and had any of the required tools, i'd fix it. It's just not worth playing the AK74 roulette game again over and being without a rifle for weeks.

Whatever... peanut gallery? Let's see you shot the rifle and now it wobbles like it should...

My question stands as correct. Otherwise you could have started modifying things and not needed to.

For Gunplumber to fix something because it doesn't meet the designers spec is one thing, for everyone to decide to fix something that isn't broken can be folly.

For all your ramblings about spare tires, I fail to see what that has to do with anything I asked. You weren't missing a recoil spring or a spare tire.

Actually, no - it should wobble considerably more than it does. It barely wobbles at all and should have noticeable wobble.

Your question stands as correct? What does a correct question stand as? What's an incorrect question stand like? Otherwise what? Otherwise....??? You are not making any sense. It sounds like you are implying that your question in some way influenced my changing or not changing the rifle which is obviously nonsense.



It's true, there is a difference between 'broken' and 'incorrectly assembled'. In either case, the problem should be repaired if it will cause problems with the rifle; do you not agree? Now considering that a piston with no wobble - incorrectly assembled - can cause the rifle to wear unevenly thus damaging and eventually changing the status of the rifle from 'incorrectly assembled' to 'broken because it was incorrectly assembled', don't you think it's worth exploring whether the issue will cause permanent damage? I hope so. If something is built so far outside of spec that it causes the item to wear unevenly or not function correctly, then, practically, it is 'broken'.



You obviously didn't see the parallel; a recoil spring is required for the rifle to function; a spare tire is not required for a car to function; your comparison is totally whacked out.

Do you see the parallel now? Neither is essential so long as the car/rifle functions as it is - ...both are simply 'how it should be' when you buy a new car/rifle.
If anything, the lack of wobble is a worse problem than a missing spare tire; after all, no wobble in the piston could actually cause the rifle not to wear correctly whereas a missing spare wouldn't negatively impact your new car's performance at all. It'd be more like buying a car with un-balanced tires. Sure, they're out of spec, but they aren't 'broken'. Well, I don't care; if the tires are unbalanced it can cause a shitty ride and uneven wear on the vehicle - thus the problem should be fixed before it causes the car to break. Anyway, we can go on all day with parallels, but the root issue is that if you buy a new item and it is advertised as being a specific way, it should be built that way when you receive it. If it isn't, you have the choice of returning it/replacing/repairing it, or going with it as-is. In this case, since the problem doesn't cause serious functional issues with the rifle, I don't think i'll be sending it back.

Yeah um OK.

Wouldnt wobble be a bad thing when using the Ultimak gas tube with the rail for optics mounting?

Why would it? The wobble lets the piston find the path of least resistance while the carrier is moving on 4 axis. Ideal would be a ball joint. It is an immovable piston that causes accelerated wear on a gun where each part isn't in absolute perfect alignment.

Wobble, not wobble, if it works then don't fix it. Fact of the matter is in some cases (in my opinion that is most cases) there is wobble in the piston and that is a good thing. While I have had some people have issues with a stiff piston not "finding its way home" I have not had that kind of problem when the piston was wobbly (except some of the UTG quadrails that were binding the gas tube). It seems like the threads on my Yugo M90A (year 1997) has less wobble than my Romanian Guard AK 47 (year 1986), but both work flawlessly. The rest of my AK collection has more wobble than the Yugo M90A as well and all work without any problems. Of course they were all built by me, but those that haven't been built by me or some one else in my build group do find their way to me on a regular basis.

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