Overdue AKM Maintenance And Questions

[Fatboy40]

Over a year ago my youngest son spent his own money on a used AKM being sold by a local shop's staff member, which on paper looked sweet, however it was very unreliable with the Perun optical controller just craping out every few shots. Finally bad Dad has sorted it out and installed a GATE Titan v3 and a 27k Warhead brushless motor, with it now running very well (especially on full auto).

 

With it having now been worked on by me I've taken a few photos that were interesting and have a few questions for others.

 

When he first bought it and when it did work, for the first few shots, it had great range and consistency and a few things probably helped this in that there's a 3D printed block keeping the hop unit steady, the inner barrel has PTFE tape wrapped around it, and there's also a sliver of a tin can and masking tape below the inner barrel at the front of the receiver (all of which I suppose kept things very much in-place). Is this all a smart thing to do with an AKM? 

 

It's no specific brand either, it's very much a mongrel. The gearbox is CYMA, and like a boneyard CYMA MP5K I sorted out there was this awful thick green grease in it which I had to clean out. The receiver and wooden furniture is a bit of a mystery, I've no idea where the wooden furniture is from, however the receiver says on the bottom it's APS and the front left of the receiver has painted Russian symbols and numbers.

 

 

 

 

[Adolf Hamster]

50 minutes ago, Fatboy40 said:

there's a 3D printed block keeping the hop unit steady

 

if it's sized well, or designed to wedge into place that's a pretty decent solution some manufacturers even use. other solutions are springs/stacks of o rings around the inner barrel to pressure the hop unit against the gearbox (these can be affected by the magazine though), or some ak hop units literally bolt to the gearbox via the front tab.

 

53 minutes ago, Fatboy40 said:

the inner barrel has PTFE tape wrapped around it

 

that's an old school bodge, some people hate it, but it's not the worst idea if the inner is a bit loose in the outer. don't need to go the whole way though just at the muzzle end as the hop will be holding the other end and you don't want to inadvertently be introducing bends to the barrel.

 

some barrels even have grooves for o-rings to stabilise the end of them which is the professional answer to that question.

 

if you're using springs to pressure the hop against the gearbox you want to be sure the tape stabiliser isn't so tight that the spring can't pull the barrel back onto the gearbox (ie barely enough ptfe to take out any wobble)

 

55 minutes ago, Fatboy40 said:

a sliver of a tin can and masking tape below the inner barrel at the front of the receiver

 

i'm guessing that's to tighten up the fitment of the barrel into the trunnion? the grub screw nominally does that but if it's real loose then certainly an option, but you're gonna want to make sure that the barrel is sitting good and square when you get it all together but that's just standard airsoft ak things. not as keen on masking tape, you want something solid otherwise the barrel could be moving when the gun gets bending pressure (eg leaning on cover).

 

 

[Austeyr]

2 hours ago, Fatboy40 said:

and the front left of the receiver has painted Russian symbols and numbers

 

Might be worth posting that too 🤔 Could help identify potentially? 

[strykerles]

I have a dboys aks74u that has the block to hold the hop in place too

 

personally never had to use tape or anything else to hold stuff in place and i've done several AKs

 

seeing as it's a mixture of different parts that could be why it has said "quirks"

 

I have a fixed stock aps receiver on the way from china for a parts build I want to do so it might be the same one 🤣

[Fatboy40]

On 24/02/2025 at 19:10, Austeyr said:

 

Might be worth posting that too 🤔 Could help identify potentially? 

 

You can sort of see it in one of the existing photo but I'll share a better one below. I wonder is APS AEG's use CYMA gearboxes or make their own...

 

[Austeyr]

34 minutes ago, Fatboy40 said:

 

You can sort of see it in one of the existing photo but I'll share a better one below. I wonder is APS AEG's use CYMA gearboxes or make their own...

 

 

Definitely an APS AKM. If I remember correctly they used to make an EBB version too 🤔 Perhaps switched out the gearbox for something more reliable?

[Fatboy40]

50 minutes ago, Austeyr said:

 

... EBB version... Perhaps switched out the gearbox for something more reliable?

 

That's sounds very logical and probably what's happened here. Yes it's a mongrel but now a very nice one 😀