I work on several M4gerys a month and I've spent some range time with several entry-level examples. My observations are as follows.
First, the triggers on them routinely suck so bad that they are difficult to shoot well. If you've got a long, grating, glitching trigger add about 3" to your potential group. Secondly, there are a lot of collapsible stocks out there Some of are wobbly at best and most are difficult to get a cheek weld on and still see the sights well. Add 2" to your potential group for those factors. Finally, lots of them have no-name flip up rear sights with substantial fore/aft and sideways play in them. I have actually had to push them forward and to one side between shots to get any kind of idea if a given rifle would shoot. The last one I tested had at least 4 MOA of wobble in the rear sight alone.
If you finally get your irons zeroed and slap an Osprey, or any similar co-witnessed sight between your irons... watch your iron sights groups wander as much as a foot at 100 yards from refraction.
Folks there are some absolutes of rifle accuracy and a ghetto'ed-up M4 violates damn near all of them at once. I keep an old, proven Bushnell on a set of extra-high rings, pre-adjusted to fit the front and back slots on the commonly seen flat-top rail. If I want to know if a given M4 will group, I rip all the crap off the top and cinch that puppy down on there. Typically I am seeing 2-3 MOA with bulk ammo like UMC 55 grain.
First, the triggers on them routinely suck so bad that they are difficult to shoot well. If you've got a long, grating, glitching trigger add about 3" to your potential group. Secondly, there are a lot of collapsible stocks out there Some of are wobbly at best and most are difficult to get a cheek weld on and still see the sights well. Add 2" to your potential group for those factors. Finally, lots of them have no-name flip up rear sights with substantial fore/aft and sideways play in them. I have actually had to push them forward and to one side between shots to get any kind of idea if a given rifle would shoot. The last one I tested had at least 4 MOA of wobble in the rear sight alone.
If you finally get your irons zeroed and slap an Osprey, or any similar co-witnessed sight between your irons... watch your iron sights groups wander as much as a foot at 100 yards from refraction.
Folks there are some absolutes of rifle accuracy and a ghetto'ed-up M4 violates damn near all of them at once. I keep an old, proven Bushnell on a set of extra-high rings, pre-adjusted to fit the front and back slots on the commonly seen flat-top rail. If I want to know if a given M4 will group, I rip all the crap off the top and cinch that puppy down on there. Typically I am seeing 2-3 MOA with bulk ammo like UMC 55 grain.