25 Yard zeroing

[Paulo_Santos]

I forgot to mention before about the zero range. I'm a firm believer in the 100 yard zero. It is the easiest to learn because everything is holdovers. No holdunders like the 50/200. And realistically, most people don't shoot past 100 yards on a regular basis, especially with irons.

[AR-10]

I am interested in the 100 yard zero mentioned above, especially since my local rifle ranges are all 100 yards.

How do I do this with a fixed front sight, and a Troy rear with no elevation adjustments?

Is this a good zero for a carbine course?

[rob_s]

On the AR system you adjust elevation on the front sight, and windage with the rear sight. I just spent a 3-day class with a fixed front sight base and a Troy fixed rear sight. If you look at the sights they are marked with arrows and notations (for example, the front sight says "up" with an arrow). Turning the sight in the noted direction moves the bullet impacts in that direction (so turning with "up" moves the bullet holes up). You can use the tip of an FMJ round to press the detent and turn the sight both in the front and the rear.

Whether or not it's good for a carbine class is going to depend on a lot of other factors, not the least of which is the instructor and whether the class is really "pistol shooting with a long-gun" or "rifle shooting with a carbine". If it's the latter chances are good that you will be re-zeroing at the class anyway.

[AR-10]

That part I get - but after reading Molon's version of the IBZ it looks like the improvised battle zeros are meant for carry handles and A2 uppers with elevation drums?

I've got a tool to adjust the elevation on the front sight, I was more concerned with the Troy rear...

[rob_s]

That's one of the problems with this antiquated IBZO business, it confuses people for no reason on equipment that nobody is using anymore.

Zero the gun at 100 yards. Set up and shoot a group about 1.5" low at 25 yards and then move out to 100 and get Point-of-Aim=Point-of-Impact. Adjust the front sight to move POI up/down and the rear sight to move POI left/right. Focus on one axis at a time, don't try to do both at once. Get the group centered at 25 horizontally, then move it up/down to get it 1.5" low. At 100 you should only need to adjust for elevation, but you may still need slight adjustment in windage. IIRC the Troy sight should move the POI 1/2" at 100 yards for each click.

[AR-10]

Thank you.

That is exactly what I wanted to know.