More problems with my dpms M4.
 

So we went out to play a couple rounds today with a few friends. I just did a series of upgrades to the gun, but it seems that the gun is shooting poorer then it was before the upgrades.

The BB's seem to almost LOB. It has plenty of bark behind the BB's and they seem to hurt just as buch as before, but they seem to arc downward instead of going straight. If tried adjusting the hob up, but that actually seemed to make it worse. Any ideas?

Thanks
Ryan

did you chrono the gun?

Try removing and reinstalling the hopup rubber. It might not be seated properly when you installed it.

Thanks for the tips guys, i did try to re-install the hop up rubber and it didnt make a differance. I actually had to put my old hop up rubber back in, because the gaurder clear hop up rubber i had was causing the bb's to jam up inside the barrel for some reason.

I didnt crono the gun yet. I dont know anyone with a tester or anywhere that would let you bring the gun down to test it.

Anything else that i could try or test?

Thanks
Ryan

Look up the "poor man's Chrono" It's a relatively consistent way of vaguely quantifying your upgrades.

Poor man's chrony shouldn't be used to guess velocities. I've tried to compare my chrony results from my guns with can shots, and it's too inconsistent to be able to come up with even ballpark figures.

No, it's really not that accurate.

Logicly, what could be causeing the downward arc of the BB's? The hop up is suppose to cause the opposite effect, the more you adjust it the more back spin thats applied and should go upward. More hopeup actually causes the oposite on my gun right now.

Moving back in the gun, we have the air tip nozzle, i put a modify nozzle on the gun, but ive inspected it, and it seems fine. Other then that, there is nothing that that comes in contact with the BB and could cause this delema.

I thought maybe it was it was the barrel itself, so i put the stock barrel on, and i have the same problem. So unless my outer barrel is somehow effecting how the inner barrel sits and for some reason causeing the downward arc??

Im kind of at a loss as to what i should be looking at. If anyone has any other ideas, im all ears :)

Thanks
Ryan

Stupid question, but you put an M4 nozzle in, right?

Yes, i actually just double checked my order form to make sure. Its a modify nozzle for an m4. If the nozzle wasnt the proper one, it would cause a bad seal on the hopup unit?

One thing i do consider odd, was that i dont remeber seeing any sort of o-ring in or on the nozzle that i recieved. In the description of the modify nozzles it says "Features an internal o-ring for improved air seal". I dont remeber seeing any sort of o-ring. Would i have had to install the o-ring in the nozzle, or would it have already been installed from the factory?

Should have been in already, I have the same one your talking about, if it isn't there, that's your problem. Contact your supplier, ask for a new one.

Still, if that o-ring wasn't there it wouldn't cause a big airseal problem like he [might be] describing.

I couldn't really undrestand what he was describing, but that's just my lack of english skills. That nozzle relies mainly on its o-ring to seal doesn't it? The one on mine is quite prominant.

Ive even tried swapping between the factory barrel and my madbull tight bore with no luck. Im really at a loss here :( Could it be an issue with the stock spring having to be put back in place? The small aluminum block where the spring hook goes into was omitted because the piston head has a bearing on it. So i ommited that piece and trimmed the hook off the factory spring.

I tried the poor mans chrono, and sometimes it will go right through the can, sometimes only through the first half.

Ryan

No, some nozzles don't have an o-ring at all. But it definitely helps the airseal in the upgraded ones.