Odd Point-of-Impact Problem, Hopup issues?

[Leon Kennedy]

So it's been a while since I sighted-in my gun, so I tried today and I'm having an odd problem. Even with hopup completely off (and I can see down the barrel when it's removed and the hopup is not stuckup) the BB's are still arcing up...a lot. I sighted the gun in after I installed a new outer and TBB last month and it was fine then, but now it just seems to be going too high.

 

The only change I have since made is installing a gas block and gas tube, which I previously didn't have. Now my concern is that the barrel is maybe being pulled up, but with the naked eye it looks pretty straight; a level confirms it. Another problem I have is that my iron sights are broken and replacements are on the way, so for now the only way I have to aim is a G&P holo. At around 50', the BBs are arcing high enough that the holo can't compensate.

 

I'm a little stuck as to what to do. My only thought is that perhaps without the gas block, my new barrel wasn't even and was slightly sagging, so once it's straightened and leveled by the gas block, my POA is way too low. Unless I'm over thinking it, it feels like I'm doing something really wrong or something's messed up.

 

Would I be better off waiting for irons, and sighting those in and then just co-witnessing the holo to the irons?

 

Edit: I'm off to work and I don't have time to edit my rambling, so my main questions are:

 

1. Could something hop-up related be causing an arc? I took the whole unit apart and I see no debris or incorrectly functioning elements.

 

2. Am I doing the wrong thing by using no irons and trying to make the red dot adjust to the point of impact? I feel like no matter which way I adjust the dot, up or down, I'm still shooting too high.

 

3. I changed from using .25s to .2s, but even with the hopup off the BBs are arcing up.

[steaktipz]

do you mean the bbs are ACTUALLY arcing up, or it just looks like that when aiming down your sight?

[Leon Kennedy]

Now I'm not so sure. Tonight I'm going to level it and put it in a vice tonight then check it. I guess I was real flustered and not clear in the head when I posted. The barrel had some play when there was no gas block. My theory is the weight of the barrel was causing it to sag, and I sighted it in with it sagging.

 

What worried me was that I could not get the holo to align with the POI no matter how high it went. Once I get home tonight I'll cool down and make sure it's shooting straight.

[Leon Kennedy]

Update time. Turns our it had nothing to do with the gun, and in the end, Dad appears to save the day.

 

I used clamps and put the gun level, then shot 5 consecutive shots at 25' in that vice so the gun didn't move. I marked the groupings and found them to be at the same height as the barrel of the gun, and found the barrel to also be level so I know that the barrel is straight. This is the good news.

 

I then used some trig, made a circle of the groupings and, keeping the gun in the vice, sighted it in. Adjusted slightly left (easy) and then the grouping was halfway between the top of the holo reticule circle and the center dot. Bad news bears is, however, that my G&P holo is broken. This is why I couldn't sight the height in and the gun always appeared to be shooting high: the up/down adjustment wasn't working, so the reticule wasn't moving up or down. Every time I thought I raised it, it stayed put, giving the illusion that the gun was shooting too high no matter how high up I moved the reticule. (Foolish of me to not notice.)

 

After some investigating with my (amazing) dad, we (aka he) determined that the small thumbscrew, which was now fully removable, was no longer glued to the inside threads of the cam which adjusts the positioning of the LED, therefore it was not turning it and was not adjusting it. He injected some loctite , put the screw in, and it's now curing in my basement.

 

With any luck, it'll be stuck in the cam's threads and work again. I got pretty lucky with the groupings still being within the reticule, but being able to put it in perfectly will help a lot.