It’s better protected.

upgraded M16A1 to A2 should have been ( pretending it's 1982)

A1 grip
A1 sized buttstock and buttplate ( with stronger A2 plastic)
A2 handguards
A1 shaped barrel 1:7 twist
full auto
A2 front sight post

a real sight more like the A1, but with the ghost-ring also

keep it simple and light

Mostly this. The A2 flash suppressor was a better fit for how they fought then also, and the case deflector is good. I’d have revised the sling attachment systems also.

RIGHT ON

For a combat rifle, I am firmly in the A1 camp.  As for a large apeture rear, I'm going to date myself here. The Army in the early 1970s equipped M16A1s with Promethium sights. The kit consisted of a front sight post with a plastic vial filled with promethium and a rear sight that had a 7mm unmarkerd aperature and a 2mm aperature marked "L". Later the Prometium sights were recalled and tritium front sights were issued. We started seeing these sights in Germany in the 3AD about spring of 1973, roughly the same time that M16A1 stocks with the trap for the cleaning kit started replacing earlier stocks with the rounded rubber pad.

The NSN for the low light level front sight is: 1005-00-234-1568 and the NSN for the rear sight is: 1005-00-071-8015

According to TM9-1005-249-23&P dtd June 1991, the Low Light Level sights are obsolete and no longer being manufactured.The only drawback came from the frustrated MTU types who insisted on smoking the sights with their carbide lamps.

http://www.coltforum.com/forums/members/8924-albums706-picture442266.jpg

This is exactly what I came here to post

Best iron sights for what.....in combat, no, for target shooting, no.....for black rifle fanboi's yes.

Some one on page one mentioned the "other' rifles had the sights adjusted at the factory and were not meant to be adjusted by the soldier using it.

That's only half right.

Soviet doctrine called for a company level marksman to zero the rifles (Mosin Nagant, SKS, AK and AKM), to ensure they were zeroed by someone who could shoot.   They used a 4 shot group, and then drew lines between the holes to find the mean point of impact.

1) a line was drawn between any two holes in the group and mark was made half way along that line.
2) a second line was drawn between that mark and a third hole in the group, and a mark was made on that line 1/3rds of the way along that line from the first mark.
3) a third line was drawn to the remaining hole in the group and a mark was made 1/4th of the way from the second mark.

In effect the lines and marks produced a weighted average for the entire group to find the mean point of impact, and the adjustments were based on that point.

The Lee Enfields were notorious for having the wrong front sight installed from the factory.  They were not pre-zeroed at the factory.  The British used a similar system to the Soviets, with factory fresh rifles zeroed by a sniper or designated marksman for the rifles assigned to a platoon or company.  Front sights were swapped between rifles or replaced from a quantity of extra front sights to properly zero them for elevation.

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I've shot M1 Garands, M14s, M1As, M16s, M16A1s, and M16A2s and in my opinion the best all round battle sight is the M16A1 sight.  However, I prefer the older sights with small apertures in both the short and long range arms of the sight. Zeroing at 250m left you good to go out to 300m and flipping up the long range aperture left you good to go from 300-400m. If you were shooting in the dark the shooting over the carry handle was suitable for the short ranges involved.

The best sight for target purposes were the NM sights on the Garand and M14/M1A, with a hooded rear sight, 1/2 MOA windage and elevation adjustments and very little play in the sight.

The A2 sight is clearly superior to the A1 sight for engaging targets beyond 400m, but the M855 cartridge itself isn't well suited to that particular role, and in the 14.7" M4 it is even less suitable.