I did my M4 like this one with a $5 iron from Harbor freight. I had to buff the high points after I was done because it was cutting into my hand. I used a Dremel with a wire wheel. Not only does it look good, but function is great.
My M4 will eat anything you can put in it, but when it was new it ran a little sluggish with light loads. This was because it was dry. After putting some oil to the internals it ran like a scared rabbit.
I went with DMW(daves metal works) ordered on Mon. received it on Wed. Color matched, fit perfectly, came with new spring, and works great. I do not know what the fascination is with waiting 3 plus months for CC.