I am putting together an M4gery.  I have the uppper already, a RRA A4 flatop, 16" barrell, and removable carry handle.  The lower receiver has not come in yet, so I got the urge to shoot it yesterday, and put that upper on my match rifle lower equipped with a WOP trigger.  It  would shooot about a 3 to 4 inch group at 100 yards using some PMC ammo.  Is this the type of accuracy that I can expect?  I also had to add a lot of left windage to get the upper zeroed, and there was no wind yesterday, is this also normal.  Thanks in advance for the help...........

What position did you shoot from?

Did you use a magnified optic?

3-4" using iron sights from a decent supported position isn't bad at all - especially considering the short sight radius.

I'd expect better if you used a scope and some sandbags off the bench.

I did shoot off of a bench, with open sights, and sandbags for support.  Will the addition of a collapsible stock later on effect the accuracy any?  

No.