Galil ACE dust cover repeatability testing

[briansmithwins]

I was curious about the repeatability of the optics mounted on the dust cover of the Galil ACE 556 NATO rifle when it's removed for cleaning and replaced, so I decided to shoot some groups after removing and replacing the dust cover. Targets were shot at a known distance 200 yard range, optic used is a TA44 1.5x mounted in the dust cover, wind was light and steady.

Starting group (UL corner) was shot, and then the dust cover was removed and replaced, next group (UR) of 10 rounds shot, then third (LL), and fourth (LR)...



Running the groups through OnTarget I get these results, all numbers are in MOA:



Offsets are from the POA (center of the target), same POA was held for all groups and there were no adjustments to the scope. Spread is the max distance from CTC of the outermost holes, also in MOA.

Doing the math, the average difference in POI (POI shift) caused by removing the top cover and replacing it is 0.5MOA. Average group size is 3.3MOA.

I am planning on mounting an Aimpoint on the rail on the gas tube and repeating the test to check if that location is steadier/more repeatable for optics.

BSW

 

[briansmithwins]

Part II:
I moved an Aimpoint Micro onto the gas tube section of rail and shot groups for dispersion and shift. Between each group I removed the gas tube and replaced it to see how much the POI changed between groups.

The four groups to the left are 55gr GECO with everything the same except for messing with the gas tube. The top right group was shot with IWI 77gr OTM, the lower right group is from ZQI SS109.



The results.


I was really tempted to toss out that one high right shot in group #1, because it looks out of place. Removing that shot would have given a group size of 1.7MOA. I decided to leave it in because I believe that, based on the other groups that I've shot, that this really is a ~3.2MOA rifle. Wanting this Galil to be a 2MOA rifle just isn't justified by my results, no matter how much I want to be so.

The 77gr OTMs have a offset of 1.2MOA and a spread of 4.2MOA.

The ZQI SS109 have a offset of 2.8MOA and a spread of 5.5MOA.

BSW