Greetings!
This is a review of the Sportsmansguide M4 type barrel that is 16inches long.
Here is the official claim on the website:
1:7" RH twist rifling. Chambered in 5.56 NATO. Includes barrel extension. Barrel threaded for a flash hider.
http://shop.sportsmansguide.com/net/cb/cb.aspx?a=606333
This was pointed out in a previous thread as being a low cost barrel. Cost was $99.00 + S&H. But what does it offer?
Here is a nice photo of the threaded muzzle:

Standard A2 and Vortex devices easily thread onto the end. No problems here! Threads were sharp and clean!

The above photo is a rough "bullet" test on the muzzle end. Obviously these are new barrels, but bore specs are important to accuracy. Lacking a muzzle gage, this is my only comparison tool. Wolf 5.56 ammo is used as an example here. As can be seen there is adequate bullet showing.
Barrel end?

I do believe this is chrome lined! See the flash of silver there!

Alternate view above on bore end.
Check out the profile. As claimed, this is an M4 profile:

You can see the location of the gas hole. This was clean and free of debris. I can measure it later, if anyone is interested. It should be a different size than full length barrels due to gas pressures.
Moving down to the chamber/ feed ramp/ barrel extension end:

Nice deep phosphate job! It was tight slipping into my AR upper (Delton) due to the phosphate. The next few photos depict how the extension/ chamber end of the barrel looks. Note that the extension is part of the barrel... as in 1 piece. Convenient since you don't have to buy extra parts... and less problems on assembly. I routinely see barrel extensions (seperate) for $17.00 on up! So this is a good cost savings built in to this AR barrel.


Once again... I am seeing something silver here! This chrome lining doesn't like the phosphate finish, as expected... Nice M4 style feed ramps.

I placed a 5.56 round into the chamber. The following photo demos how far into the chamber it went, by hand.

So would I purchase another one? YES! And actually I did. I am thinking about making an M4A4 and also an AR pistol. This would be a nice low cost barrel for the previous projects.
Since this is a site for builders, I would also make the case that this would be an excellent "project" barrel.
No range report yet due to time and parts needed to assemble a rifle.
I did not see any maker marks, or country of origin (assume US due to import ban?). There is no caliber marking like on some barrels I have purchased.
I would like anyone else's feedback on their SG M4 style barrel!