so I was zeroing my new rifle I put together, and in order to get a 50m zero I had to bottom out my front sight. My first group with a mechanical zero were about 11" low. I am definitely not a cherry. I’ve been using these weapon systems for about 10 years, so I know it’s not shooter error. Maybe it’s assembly error. I was starting to fear that I wouldn’t have enough adjustment, but just barely got it.
What gives? I’ve never seen this before. My Aimpoint is tracking the same with the red dot right at the tip of the front sight post. I don’t know if it matters or not, but both groups I shot pre-adjustment with the mechanical zero iron sights, and the factory setting on my aimpoint also lined up.
It’s a BCM upper with Colt barrel and BCG. I received it with the FSB installed.
What rear sight are you using?
Until we know what rear sight you’re using, all I can suggest is:
Front - opposite
Rear - same
Edit: glad to read you’ve got it sorted out.
Make sure that the barrel is secure and the FSB is straight as best you can.
Then I would bring it back to mechanical zero and start over. Use some ammo that you know is good. Use only the irons and not the red dot. Knowing the rear sight is also helpful.
oh yeah, I forgot to mention it.
I was using a DD fixed rear.
Anyway, I went back and checked it. I still have 11 clicks more of adjustment. I believe I screwed it down 22 clicks while conducting zero. I didn’t bring a front sight tool while shooting, so I was using the pick on a gerber. When it got low I was encountering resistance, and thought bottomed out. Kind of a retard moment.
This is still the lowest ever seen a front sight post.
Iraq guns, I zeroed the irons first, and then the aimpoint. The barrel is still tight.
I included some pics, but I don’t think they show it very well.
BTW: I’m not trying to be super OCD guy. It just seemed odd to me.