I want to build a correct as possible early commando.
You know the first colt with 11.5" barrel and 5.5" flash hider.
Were they slabside uppers are A1 uppers?
Any pics of one?

So the CAR flash hiders/supressors are considered sound devices by the BATFE?

CRC

No, just the XM-177 moderator that had an inner baffle to reduce the sound reports a few DB's.

This slight reduction was to make the sound report of the shorter barrel sound of that of a standard 20" rifle, and prevent the reports of the rifles announcing that special forces were in the area.

The XM-177 had a 10.5 barrel, then was changed to the 11.5" barrel later on (XM-177E2). With the mod, both barrels are still shorter than the 16" allowed, which would require not only a Suppressor stamp, but a SBR stamp as well (if not a MG) on a semi rifle.  

The reason for the 11.5" barrel, and the 5.5" permanently attached FS is to get the barrel to the legal limit for a standard firearm of 16". Granted that this combo is fun for short ranges due to the fireball that is thrown out of the FS, the short barrel really gives up velocity of the bullet.  In average, you looking at bullet speeds from the barrel around the 2500 mark, and not the normal 3000 fps from a standard 20" barrel.

Quoted: No, just the XM-177 moderator that had an inner baffle to reduce the sound reports a few DB's. This slight reduction was to make the sound report of the shorter barrel sound of that of a standard 20" rifle, and prevent the reports of the rifles announcing that special forces were in the area. The XM-177 had a 10.5 barrel, then was changed to the 11.5" barrel later on (XM-177E2). With the mod, both barrels are still shorter than the 16" allowed, which would require not only a Suppressor stamp, but a SBR stamp as well (if not a MG) on a semi rifle.

What's the difference between a XM177E2 and the XM177E2S?

Got it

Thanks

CRC

Quoted: What's the difference between a XM177E2 and the XM177E2S?

I've never heard of a E2S,

The first XM-177's were without Forward assists and had a 10.5" barrel.  The later XM177E2 had a FA, and the barrel were 11.5" to allow a M-203 type lancher to be fitted to the rifle.

If there was a S series, then my guess is that the Mod was pulled, and better working sound supressor was installed instead.  

As far as range goes 95% of infantry engagements take place 100 yds and under 50 yds 75% of the time and thats since WW2.The 11.5/5.5 is plenty for a self defense personal protection home land defense rifle.But I like 14.5s with a phantom just incase I need a bit longer range.Check out this site www.isayeret.com and see how the IDF employs their M16s in all different barrel legnths.They even use an 11.5 for sniping out to 300 yds check it out.Thats why I stick with the shortest possible leagal barrel lengths.I have a 20" but thats my match rifle for DCM use my other 3 carbines are 11.5/5.5 and 14.5 with phantom.My wifes rifle is a Bushy carbon model#4 with a 14.5/izzy brake M4 profile carbine...she likes them lighter as mine are HBARs...but thats a whole other debate.