Shooting High & Right, What Needs Adjusting?

[sfraser3]

Took my new build to the range yesterday. Set-up on a 50-yard target with iron sights and ran two groups of five rounds through checking for functionality. Everything seemed to work fine except the point of impact of the rounds was about 8-9 inches high and 8-9 inches right. Suspect a barrel timing issue but would appreciate input before I start wrenching.

Thanks!

[Hebrew Battle Rifle]

Assuming that the rear sight aperture is fully to the rear, and assuming that you are shooting military surplus ammo, the center of the groups should be about an inch above the point of aim at 50yrds. Try turning the front sight post counter clock wise (looking from the top) 8 clicks or so and shoot it again. To bring the strike of the rounds down, the front sight needs to go up.


For the windage, assuming that the rear sight aperture is centered and the lower is also centered, turn the left side sight adjustment screw 8 clicks counter clock wise and then turn the right side screw 8 clicks clockwise. Fire another group and see where the center of the groups is relative to the point of aim. Continue to adjust the rear sight until the center of the groups coincide with the center of your point of aim.

With the rifle unloaded, remove the gas piston and spring. Put the piston back in as normal but leave the spring and gas plug off. Lock the bolt to the rear and then lift the muzzle toward the ceiling. What does the piston do?

[stimpsonjcat]

If it is a timing issue, then it is too tight.

[garyd1961]

It's not a timing issue until you run out of adjustment.

[sfraser3]

Thanks for the feedback and suggestions. Much appreciated.

I removed the gas plug and piston spring then re-inserted the piston as Hebrew Battle Rifle suggested. When I pointed the barrel to the ceiling the piston slid down into the chamber. The piston did not bind. In fact, it freely slid back and forth as I tilted the barrel first up then down. I adjusted the front sight and rear sight as suggested. I will get back to the range in a week or so and give it a try. If adjustments don't resolve the POI issue I will look at barrel timing as a possible cause.