G&P M4a1 firing problem.

[tiger-unit]

I just got this gun brand new yesterday and I went to fire it, and the performance was crap...bb's were shooitng out like 5 feet, and then 30 ft and sometimes FAIRLY far, then other times not far at all, if anyone knows what could be wrong, I have adjusted the hop-up and it doesnt do anything, supposedly it shoots 400 fps from the factory, and it doesnt even seem like that at all, help would be appreciated, thanks.

[Affliction]

Originally Posted by tiger-unit

I just got this gun brand new yesterday and I went to fire it, and the performance was crap...bb's were shooitng out like 5 feet, and then 30 ft and sometimes FAIRLY far, then other times not far at all, if anyone knows what could be wrong, I have adjusted the hop-up and it doesnt do anything, supposedly it shoots 400 fps from the factory, and it doesnt even seem like that at all, help would be appreciated, thanks.

Is the snap (the amount of sound) from the gearbox any louder/quieter depending on how far your BBs go?

[CDN_Stalker]

Timing is set too far advanced. Causes the nozzle to not fully seat all the way at times on full auto. Problem (observation anyways) with G&P AEGs is that the sector gear's "tappet nubb" is too close edgewise to the tappet plate, causing the tappet plate to not fully move forward to provide a good seal in the breech (hop up). The G&P sector gear has a ~1/4" tappet nubb, as opposed to the ones found on most other gears that is 1/8" wide. Setting the others at the "1 O'Clock position" sets the timing properly (assuming one eyeballs through the center of the nubb), but doing the same with G&P gears sets it so the edge presses against the front edge of the tappet plate, preventing it from seating fully. I accidentally noticed this when working on a G&P SPR earlier this year, caused some BBs to rip out to the target 30ft away (indoor range) and others to almost roll out of the barrel to land 10-15ft away.

Need to get the mechbox open and set the timing so that the rear edge of the sector gear nubb has roughly 1mm (clear anyways) of space away from the front edge of the tappet plate at full rest.

Sorry, confusing to describe, but if you give that info to whomever will fix it for you, they will understand.

And yes, even though the gun is brand new, what's to say that it wasn't done that way accidentally at the factory? These things ARE assembled by hand, so mistakes are common.

[mcguyver]

the previous post is partly correct. it is your timing. however it is not an adjustment problem. g&p uses a prometheus hard tappet. it is red and made of aramide. it also lacks the semi-postive grab indentations on it where spur gear grabs on to pull the tappet back. the "nub" is sliding under the tappet and not grabbing it correctly. re-shimming the gear box may help by lifting the gear to engage the tappet better. g&p uses only the best parts for hi- speed and high torque applications except the tappet and selector plate(also prometheus). have replaced these on several g&p m4 and spr's. suggest replace your tappet. it may already have a groove wore into it by the gear "nub".

[CDN_Stalker]

I like his answer better! Lol

Actually, I had to replace the SPR's tappet plate after the first days use (Apoc is heavy on the trigger). End of the day, gun was cycling but not spitting BBs. Looked inside and aw the nozzle not moving. Cracked it open, tappet plate busted in half. Replaced it and it's been running fine ever since.