DE ump problems

peter-pantslez

ok im having problems with the consistancy of a ump. its fring from between 127 - 290 fps. will a new springs solve this?

also every now and then it dry fires (and its nothing to do with winding the mag) but when you look the the mag well the air nozzle doesnt seem to go all the way back. from what i can remember this broke before and i replaced it with a m4 one so maybe its too long, what would be the right air nozzled for it?

hairyman

If any thing the M4 Nozzle should be slightly shorter than the UMP nozzle,,,,i would change the nozzle just to be on the safe side(any G36 air nozzle will work),,,my bet is that this is causing your air leak and sporadic FPS readings as its not seating in to the hop up correctly.

Flip the AEG upside down and manually load a bb(no magazine),,fire the aeg(in a safe direction) while keeping your hand over the magwell,,if you can feel a blast of air then its down to airseal around the nozzle.

peter-pantslez

hairyman wrote: »

If any thing the M4 Nozzle should be slightly shorter than the UMP nozzle,,,,i would change the nozzle just to be on the safe side(any G36 air nozzle will work),,,my bet is that this is causing your air leak and sporadic FPS readings as its not seating in to the hop up correctly.

Flip the AEG upside down and manually load a bb(no magazine),,fire the aeg(in a safe direction) while keeping your hand over the magwell,,if you can feel a blast of air then its down to airseal around the nozzle.

thanks for that i was planning on changing the nozzle but wasnt sure which one to get.

peter-pantslez

ok changed the air nozzle today and its a bit better but still going up and down between 240-280fps. is this normal or would a new spring sort this out?

Leftyflip

peter-pantslez wrote: »

ok changed the air nozzle today and its a bit better but still going up and down between 240-280fps. is this normal or would a new spring sort this out?

Have you checked the compression?
Try teflon taping the hop chamber, should get you a few extra FPS.

peter-pantslez

Leftyflip wrote: »

Have you checked the compression?
Try teflon taping the hop chamber, should get you a few extra FPS.

how do i check the compression? and iv a new gaurder hop up rubber in it already but how do i teflon the hop up chamber?

buy teflon do you mean ptfe tape

Leftyflip

peter-pantslez wrote: »

how do i check the compression? and iv a new gaurder hop up rubber in it already but how do i teflon the hop up chamber?

buy teflon do you mean ptfe tape

Take the piston and cylinder out.
Place your finger over the cylinder head, where the airnozzle sits.
Push the piston in, i if slides in easily, use some silicone oil or grease around it and try again, ideally you want there to be a good bit of resistance.

PTFE or Teflon tape (same thing)
Wrap some around the hop rubber and put it back into the chamber.
Then wrap some PTFE tape around where the barrel exits the chamber.

peter-pantslez

Leftyflip wrote: »

Take the piston and cylinder out.
Place your finger over the cylinder head, where the airnozzle sits.
Push the piston in, i if slides in easily, use some silicone oil or grease around it and try again, ideally you want there to be a good bit of resistance.

PTFE or Teflon tape (same thing)
Wrap some around the hop rubber and put it back into the chamber.
Then wrap some PTFE tape around where the barrel exits the chamber.

cool il try all that and see what happens before i get a new spring.

there is a oval hole in the cylinder will that matter?

Leftyflip

peter-pantslez wrote: »

cool il try all that and see what happens before i get a new spring.

there is a oval hole in the cylinder will that matter?

That won't matter, the piston only starts acting as it passes that.
So after the hole in the cylinder is where you want to compression.

peter-pantslez

ok iv tefloned up everything and its much better and shoots between 280-320 but every now and then it will drop down to 170 for one shot then go back up

anymore ideas?

Dread-Lock

Mine randomly does that as well.
Although I know I have a damaged tappit plate. I didn't think it was causing that issue, but I guess it might be. I've got a new tappit plate, just haven't gotta round to replacing it yet. So I can't say if it'll fix that issue. Sorry I know thats not much help, but did you happen to notice any wear on the tappit plate when you had it open?

peter-pantslez

Dread-Lock wrote: »

Mine randomly does that as well.
Although I know I have a damaged tappit plate. I didn't think it was causing that issue, but I guess it might be. I've got a new tappit plate, just haven't gotta round to replacing it yet. So I can't say if it'll fix that issue. Sorry I know thats not much help, but did you happen to notice any wear on the tappit plate when you had it open?

cool if you get around to replacing it and it sorts it out will you let me know?

when i had the gear box open i thought there was something wrong with mine.

Dread-Lock

peter-pantslez wrote: »

cool if you get around to replacing it and it sorts it out will you let me know?

when i had the gear box open i thought there was something wrong with mine.

I will indeed. Sure I might as well do it this weekend, I've been putting it off as I have so many guns at this stage I'm never stuck for one . Now that I actually have a reason I might as well do it.

peter-pantslez

Dread-Lock wrote: »

I will indeed. Sure I might as well do it this weekend, I've been putting it off as I have so many guns at this stage I'm never stuck for one . Now that I actually have a reason I might as well do it.

good man let me know how it goes:D