OK this is my first post here so be patient.  I want to put a kit together.  The kit I am looking at is from M&A Parts.  I have read everything I can find on here about them and did'nt see any negatives.  I know I want the A4 flatop 20" barrel with gas block instead of A2 sight as I plan to mount variable power scope for some target shooting and a few varmints.  My eyes are not what they used to be for iron sights.  The dilema is I have a choice of a threaded A2 Suppresor or a 11 degree target crown with press on suppressor.  For the average shooter is the target crown going to make that much difference in accuracy  in an ar setup?

You will notice no difference in accuracy. I'd go threaded. Welcome to the site!

I disagree. If there was no advantage, why would they make the crown? The gases escape the barrel evenly with the crown. With a threaded barrel and a Flash Hider/Suppresser, the gas exits the barrel then the ports of the FH. With the half bird cage, the holes are on top, the gases escape through those but the gas escapes off the bottom of the cage where there are no holes. This uneven gas flow causes a change as apposed to the Crown. I have been told on the forum that it doesn't affect your rounds. I have been told by Bushmaster that it does. I ordered one to find out for myself. I had a barrel threaded at my local Gun Smith and attached the FH. When I took it to the range, I used the same ammo, same range, same everything except the added FH. My groups went from 3/8" MoA to 1" MoA. You won't see a great amount of difference but you will see some. I guess the question you have to ask is how much is acceptable for your application. Keep in mind that a 1" at 100 Yards is a 2" at 200 and 4" at four hundred, etc....

You'll hear a lot of different things from those who say they can't "tell" a difference but honestly it depends on how you "Gauge" a difference. I assume you are not looking for a super accurate rifle going with a "Kit" rifle so for that application, I would have to say that you probably won't "Notice" a difference.

Semper Fi

My opinion:
A 11 degree crown is nice, but not needed.
If it were to be a match grade bench rifle, with worked up hand loads, then a 11 degree would be the way to go.
For a good accurate all around rifle,  a regular flash suppressor will serve you well.

I just thought I would put one together for experience and do some shooting.  I am not looking for one hole groups.  I have been shooting bolt rifles all my life until I bought an AR10 last year.  Well should I say more now I need a 15.  200 yds and on rare occasion 300 max.
Thanks for the help