Old Marine here.

Question. Help me to compare and contrast shooting the known distance course (KD Course) at 500 yards with an M16A2 iron sights to M4 with acog to a civilian .75 MOA accurate AR15 with 18X scope.

When I was in the first time I used iron sights and shot high expert (looking at my old rifle range books I think I was at least a 4 MOA shooter more like 3 MOA).

When I got recalled after a year and a half I still qualified using iron sights but then I deployed with the Trijicon 4x32 acog sight (with bible verse).

I was just wondering one day how much easier it is to qualify with the acog vs iron sights.

Also, if I was a good shooter with M855 ammo and a beat down 10-year-old M16A2 what could I expect with a nice civilian rifle as detailed above? With 80 gr Bergers could I expect 5 inch groups or 10 inch groups or what?

I don't have any opportunities to shoot out past 100 yards these days.

Thanks for any help.

Never tested it yet in theory the magnified scope even at 4x would be better than irons out to most ranges as better sight picture. With new then you would be the component that would cause any flyers.

I'm in the same boat as you. I started with irons and field firing, and finished with "RCOs" and Tables 1-4. One thing to remember: although the Marine Corps adopted an optic with a BDC measured in meters, they still used (as of 2013 at least) KD ranges measured in yards.  

Irons are set up to with MOA adjustments. You move the aperture according to your distance, in yards, from the target. It's really as simple as that. With the optic, however; at 500yds, you're looking at around 450m. Seems easy enough, but I RARELY saw an ACOG with a 500yd hold that was actually in between the "4" and "5" line on the BDC. So, from the 200 and 300yd lines, it was pretty easy. In fact, if the sun was behind our targets and the day was clear, we could call and plot our shots without the pit pulling the target down. From the 500, though--at least in my experience--the ACOG got a little wacky.

As far as the civilian set up, I'd expect anyone to shoot the shit out of the x-ring with an 18x scope...that is if you're not free-handing it. I hate shooting with high power scopes without a rest of some sort.

80-85...I build ar platforms, put scopes/optics of many kinds. My go to SHTF is iron sights no scope. Still reliable, youngin's now days couldn't shoot 50 yards without a scope or red dot...or with it!

I'm just a civilian, but it seems with optics, shooters improve quicker. A few that have switched to optics noticed flaws in their position or fundamentals, made an adjustment, then applied it to irons with improvement. Many experienced shooters saw a dip in their scores at the first match or two, then back to their average.

Several XTC records were just broken at Camp Perry, including a few many-X cleans at 600yds with a 20" AR and 4.5x scope. The X-ring is 1 MOA, 10-ring is 2 MOA. So yes.

Thanks to everyone for their comments!

Funny stuff with the RCO's.
I am surprised you could see the bullet path with only a 4X power scope.
I shot intramural once and they gave us a 20X spotting scope. I just assumed you need high power to see the bullet trails.

Leave that crap for GD. "Youngin's" these days can do fine with either.

No military experience here, but there is little comparison between a reliable optic and iron sights at extended ranges. Hitting the target is one thing; being able to first identify it is just as important (obviously doesn't apply to a KD range). The whole "aim small, miss small" concept works much better when it's only the reticle of an optic rather than a non-magnifying set of iron sights subtending the target.

You need 20x to see mirage in front of the targets or off the 300yd line when the focus is dialed back.

On a real hot range like Twentynine Palms, 20X shows so much mirage you cannot make the targets out.  I always used 7X binos to read mirage.  Wind is always wonky in the desert, more reliable learning to read mirage.

Definitely an interesting topic. I'm a youngin by all standards, but probably have done by my best shooting with Irons. I started with A2 irons shootings CMP high power before they started using optics as a teenager.

I found the irons to be extremely accurate in that controlled environment with young eyes, reloaded bullets, a white oak upper, and sights tuned to the target size.

Spreading my interests into optics has changes a lot of shooting principles for me. I find I can only repeat my accuracy from iron sights while shooting unregulated targets (varying sizes and shapes at different ranges) when using high power optics (10x or higher). Speed in target ID and acquisition comes with fixed magnification optics <4x.


At Quantico right now actually. Very cool to see all the ranges and rigs.

Hey @Mod_Zero,

If your are still there and have access to the weapons training battalion armory (ask first! I don't want you to get shot lol) take a picture for me. Take a picture of a picture on the wall. It is of 10 Marines, 10 shots each at 1000 yards, all in the black. I think it was from the 1920's or 1930's.

@Happy2shoot,


Let me see what I can do tomorrow. I'm not very familiar with the base. I know we are setup on Range 4. As a civ I'm not sure they'll even point me in the direction of the armory haha.

Range 4 is the 1000 yard range. I remember walking to pull targets on range 3 while the snipers were shooting steel. Zip, clang, bang. Zip was the bullet going by. Clang was the target being hit. Bang was the rifle shot.

IM inbound

Bump for updates. @Mod_Zero

I shot mid 220s in boot with irons and mid 240s in the fleet with an acog. Probably would've done better with irons if I had continued to use them. With an acog, it's pretty easy to wear out a shot spotter disk.

UPDATE:

I was able to shoot at a range to 300 yards! Still not 500 yards but fun.

When the wind was still i shot a 3 round group that was about an inch, and a 4 round group that was between an inch and 1.5 inches!

Boltgun (bipod and rear bag with bunny ears) and scope 1/3 to half MOA.
M-16A2 and irons 3 or 4 MOA.

With a White Oak service rifle and my ammo,  I would have been able to shoot or come close to a perfect Qual score easily with an optic.

Expert with irons in the corps 88-92.  Shot NRA highpower after.