Sig Sauer 556 Grouping?

In lieu of the other answer I was going to give ... if you can cover 4 shots with a quarter at 100 yards then the rifle and the ammo are doing fine. An outlier is an outlier for a reason. As a competitive shooter for 5 years I would assume that you are good enough to be able to call your shot so you know when you've contributed to the group opening up. Lacking any other evidence, I'd be inclined to think that is more likely the case.

Thinkingblade

Sounds about right to me.

Grouping/accuracy have a lot of factors working around it. These include.

-The gun itself, not just the model and make, but the individual gun you are using. This could mean anything from barrel wear, to the trigger.

-The ammo used

-The ability of the shooter

-The sights used, even iron sights can vary in quality and consistency.

When most people writing reviews for various gun magazines and such do evaluations on grouping, they usually try to take the "human" factor out of it, and focus more on the gun itself. They do this by doing their tests from the bench, or even on a mount. They use high quality optics, usually a magnified scope to eliminate variations. They try various brands of ammo, everything from cheap surplus, high quality match, and custom handloads.

For iron sights out of a sig 556, that's a perfectly acceptable grouping. You will be able to tighten it up a bit if you play around with ammo, practice, and almost certainly if you put a magnified optic.

Sigs are known to be incredibly reliable, good guns. But many piston driven guns, such as the sig, tend to be slightly less accurate than say, a free floated barrel on a DI gun. This just has to do with barrel harmonics and such. Don't feel dissuaded though, sigs are meant to be fighting guns, not competition guns.

With iron sights, it's not terrible, but it's not great either (unless it's an SBR version). The gun should be capable of closer to 1"-2" groups at that distance. Properly using iron sights is a lot harder than most people think.

It indicates more about the shooter than the rifle or ammunition.

These days, a decent rifle is expected to shoot groups measuring 2 m.o.a. or less.

After properly installing a decent 3-9x40mm scope and using a bench-rest, the groups should be much smaller. If they aren't, then start trouble-shooting. :-)

It sounds like you need a lot more practice with iron sights.