Question for AR experts.

[gunrunner]

So i took my A4 20'' out yesterday to sight in the Leupold AR scope i just put on. Now i had sighted it in previously but i had a full birdcage on her at the time. I didn't like the way it created a dust signature and just kicked up a hell of alot of dirt and dust when firing prone. So i installed a standard comp/birdcage with the bottom filled in. It changed my POI! Using the same ammo out of the same box i was hitting 8" high and 5" left at 100yrds. I re-zeroed for the new configuration and all was fine. I was just wondering if it is common for your POI to change that much with the installation of a comp/flash suppressor? I thought that the bullet would be gone before the gas exits the barrel. So how can it shift the POI that much?

 

[GunnyHwy]

It seems to make sense that it could happen. You would certainly be changing the direction of the gas flow at the exit. With regard to the bullet already having left the barrel, think if it as a golf swing follow through.

 

[E.Shell]

Changing the mass at the muzzle will change the dynamic. Changing the F/S torque value will also change the dynamic. Changing the design of the muzzle device can change gas flow around the muzzle and overall accuracy. Any of these can change point of impact, and you may have done them all.

FWIW, USAMU only torque their flash suppressors hand tight, just enough that they won't come loose. They have found it does affect accuracy and too much torque is detrimental.

 

[MDMOUNTAINEER]

Good Tip!

 

[gunrunner]

Changing the mass at the muzzle will change the dynamic. Changing the F/S torque value will also change the dynamic. Changing the design of the muzzle device can change gas flow around the muzzle and overall accuracy. Any of these can change point of impact, and you may have done them all.

FWIW, USAMU only torque their flash suppressors hand tight, just enough that they won't come loose. They have found it does affect accuracy and too much torque is detrimental.

Come to think of it. I did have to go about 1/4 turn past hand tight in order to get it indexed properly. I guess i'll have to order another vortex for this gun too.

As far as flash suppression goes the vortex seems to be a hands down winner. Check this out.

 

[gunrunner]