[noobnr39]

Hello dear Snipers,

Ive been getting into teching, and my first own build is an upgraded Cyma 098 SR-25 style DMR.

right now its rigged with :
v2.5 gearbox,
aluminum dual oring cylinder head
aluminum single oring piston
metal teeth piston rail
Nuprol g36 nozzle ( had the same dimensions as the stock nozzle, still going to order an SHS AR10 nozzle )
Titan Gate Basic
8mm Ball bearings
Stock 1:18 steel gears
M120/125/130 Spring ( quickspring system )

Prometheus 6.03 stainless steel 440mm barrel
Maxx ME hopup
Maple leaf Omega bucking

Ammunition 0.3 nuprol rzr and 0.4 novritsch

Now, since the barrel upgrade, accuracy has gone up a lot. but at around 30m~40m range, the trajectory is starting to get random. shooting off at random directions. ( to be clear it flies laser straight for the first 20m , groupings of 5cm )

It is literally driving me nuts.

Ive fixed the airseal, constant power, shimmed the gearbox, got a nice smooth sound and freely spinning gears.

I still intend to flathop/R-hop the replica.

I cannot figure out what is going on, at first i thought it might be the wrong cyl/barrel ratio( have been trying to find what the effect is of a bad ratio )

but it also seemed that the hop is inconsistent.

so i checked the play on the arm and the nub, which is supernice and tight, no shim needed,

the buckingnub is at the 12oclock position,

what i did notice even after the C-clip attached, the barrel could still turn a bit... which also seemed off to me, but i checked after some shots of it dislocated and it does not seem like it...

it is really driving me nuts...

could this still be about the nozzle ? is it the ratio? munition? bucking ?

any help is greatly appreciated, i cannot assume that 40m will be the final effective range of this DMR build...

I am greatly willing to learn and hone my skills as an airsoft armourer...

Kind regards and thanks for reading.

BTW My name is Rick, its a pleasure to be part of the forum

 

[Plazmaburn]

Which nub are you using in the maxx? and what degree maple leaf? Also when you adjust the hop up does it get harder to turn?

 

[SiliconeSword]

I suggest that you try your original barrel, and go from there.
I don't have a clue whats going on but that will certainly narrow things down.

 

[noobnr39]

Original barrel had the same problem, cheap brass 6.03. you can see it having all kinds of crap on the inside, bucking is a yellow maple leaf concave, i think thats the 60 degree ?

 

[SiliconeSword]

Original barrel had the same problem, cheap brass 6.03. you can see it having all kinds of crap on the inside, bucking is a yellow maple leaf concave, i think thats the 60 degree ?

I honestly don't have a clue, you should listen to whatever Plazmaburn has to say lol

 

[noobnr39]

Which nub are you using in the maxx? and what degree maple leaf? Also when you adjust the hop up does it get harder to turn?

I use the Mexx concave nub that came with the Mexx, it doesnt get harder to turn

 

[noobnr39]

Original barrel had the same problem, cheap brass 6.03. you can see it having all kinds of crap on the inside, bucking is a yellow maple leaf concave, i think thats the 60 degree ?

I honestly don't have a clue, you should listen to whatever Plazmaburn has to say lol

ah no worries man dont blame you 🙂

ive been working on this for 2 weeks now

 

[whalesmash]

How does your hop up set fair with the BB drop test?

 

[Plazmaburn]

Check to make sure the nub fits in the barrel window. if it does not then that is part of your problem.

 

[noobnr39]

Check to make sure the nub fits in the barrel window. if it does not then that is part of your problem.

nub fits, i can clearly see the concave shape at the 12o clock

 

[noobnr39]

How does your hop up set fair with the BB drop test?

what do you mean by this ?

with no hop the BB goes straight through.. hop at 2, the BB stays

 

[noobnr39]

is the axial stability of the hopup chamber itself an issue perhaps?

by this i mean, when i insert the barrel and the chamber in de upper receiver, push it to the far end, it can rotate CCW a little bit. would maybe explain the random shots to the left but not to the right..

 

[whalesmash]

what do you mean by this ?

with no hop the BB goes straight through.. hop at 2, the BB stays

If your BB drops straight past the bucking lips with the hop up off then the lips are too loose. Rather strange considering you're using the Maxx model hop unit. You can either try wrapping the bucking lips with a single layer of teflon tape or try another bucking that's a bit tighter at the lips.

 

[1tonne]

So you changed the air nozzle. Try putting the old one back in. I wouldn't be surprised if this is the issue. Air nozzles can be a pain in the backside.

 

[noobnr39]

So you changed the air nozzle. Try putting the old one back in. I wouldn't be surprised if this is the issue. Air nozzles can be a pain in the backside.

the problem was already there with the old air nozzle, non airseal plastic piece.

if you insist this might be the problem i can try to change it back.. but i would lose the airseal.

how can the nozzle affect the trajectory issue like this ? i mean i can start replacing everything part by part, but i want to know why or how this is happening aswell

 

[noobnr39]

BTW, thanks all of you already for trying to help me out <3


a little thing i tried with some succes, i cut a 2mm piece of the end of an old bucking, and put it around the alignment bars on the hopup unit, now it fits more snuggly inside the upper receiver/outer barrel.

i do notice a better consistency in shots, but the randomness of the trajectory still exists.

i will be trying a new bucking today aswell

 

[1tonne]

If not correct, it can make an air leak. If the air leak is not a consistent one, then it will create fluctuations in fps.
Another thing could be that the new air nozzle grabs the cylinder head nozzle a little too much. In this case, shorten the tappet plate spring.

 

[noobnr39]

fluctuations in fps are a possible cause for the random shift of direction after a certain distance ?

EDIT: just chronoed,

it is a consistent 1.69joules, with a deviation of 3fps max

 

[atmcash]

Hello dear Snipers,

Ive been getting into teching, and my first own build is an upgraded Cyma 098 SR-25 style DMR.

right now its rigged with :
v2.5 gearbox,
aluminum dual oring cylinder head
aluminum single oring piston
metal teeth piston rail
Nuprol g36 nozzle ( had the same dimensions as the stock nozzle, still going to order an SHS AR10 nozzle )
Titan Gate Basic
8mm Ball bearings
Stock 1:18 steel gears
M120/125/130 Spring ( quickspring system )

Prometheus 6.03 stainless steel 440mm barrel
Maxx ME hopup
Maple leaf Omega bucking

Ammunition 0.3 nuprol rzr and 0.4 novritsch

Now, since the barrel upgrade, accuracy has gone up a lot. but at around 30m~40m range, the trajectory is starting to get random. shooting off at random directions. ( to be clear it flies laser straight for the first 20m , groupings of 5cm )

It is literally driving me nuts.

Ive fixed the airseal, constant power, shimmed the gearbox, got a nice smooth sound and freely spinning gears.

I still intend to flathop/R-hop the replica.

I cannot figure out what is going on, at first i thought it might be the wrong cyl/barrel ratio( have been trying to find what the effect is of a bad ratio )

but it also seemed that the hop is inconsistent.

so i checked the play on the arm and the nub, which is supernice and tight, no shim needed,

the buckingnub is at the 12oclock position,

what i did notice even after the C-clip attached, the barrel could still turn a bit... which also seemed off to me, but i checked after some shots of it dislocated and it does not seem like it...

it is really driving me nuts...

could this still be about the nozzle ? is it the ratio? munition? bucking ?

any help is greatly appreciated, i cannot assume that 40m will be the final effective range of this DMR build...

I am greatly willing to learn and hone my skills as an airsoft armourer...

Kind regards and thanks for reading.

BTW My name is Rick, its a pleasure to be part of the forum

did you ever figure this out I have the same setup