It's very rare to see someone good enough to weld it so that you will not require a lot of finish work to make it look "factory". If you found that person, they would be so inundated with work of various types to be too busy to do a $60 weld job for flash suppressors.
If you did it yourself without the proper knowledge, you get whatever you get. It might be permanent, but it might also be permanently ugly as hell. It could also change the strength or hardness of a pretty key piece of your barrel.
I suggest you proceed with caution unless you are a knowledgeable welder, machinist, gunsmith, or other metalworker.
As to the wannabe comments, they need to get knocked right the hell off.
"I'm not saying I invented the turtleneck. But I was the first person to realize its potential as a tactical garment. The tactical turtleneck! The... tactleneck! - Sterling Archer"
"Courage is not the absence of fear, but rather the judgment that something else is more important
than one's fear. The timid presume it is lack of fear that allows the brave to act when the timid do not."