I am new to the AR-15 and recently purchased a MP-15A. I have been able to learn a lot about it watching youtube, but there are several things I can't figure out on my own.

1. I bought a new ejection port door from spikestactical, but I haven't figured out how to swap the stock one. It seems I need to remove the delta ring to slide the bar out. Am I correct, if so how do I remove the delta ring? I know how to knudge it down to remove the hand guards, but that's about it.

2. If I wanted to swap the stock flash supressor, how do I remove it on the MP-15A? All the videos I have seen show using a hex key/allen wrench to loosen the bottom and slide it off. Mine does not seem to have any type of screw holding it in place.

Also, how good are S&W AR-15's compared to other versions? Is it considered a budget/starter gun? Any input is greatly appreciated.

The flash hider on a AR just screws off,use a 3/4" wrench,but wrap a piece of tape around it first so you dont scar up the finish.The threads on your S&W are 1/2-28,so make sure you buy the right hider,brake,etc if you decide to change it.The S&W is close to top of the line when it comes to AR's,very dependable compared to others.As far as changing out the parts you asked about I have no clue,I just bought mine a few weeks ago already had a quad rail,scope,laser sight,tactical flash light,bipod,colapsible stock,front pistol grip on it.I dont see much reason to change anything else on it.Oh and I just ordered 3 Magpul Pmags for it,a must for an AR..

Your port door should be removable by removing the forward clip (very small) on the hinge pin and sliding the pin to the rear.

Thanks for the input guys. I was able to swap the ejection port door with your instructions.