Do I need to change the buffer tube and spring or just switch out the upper? Thank you.
They are the same. Assuming that you don’t have some WECSOG stuf happening. Assuming you have a good barrel, you should be able to run it with at least an H buffer.
Can’t he just get a middy gas tube and a gas block and put it on his Carbine gas barrel?? 
Only if he runs it in tandem with the original gas system.
To the OP’s post, you MAY need to swap the buffer/spring to prevent short stroking, but run it first. I would think that 99.9% of the time a quality rifle will run just fine.
Do you know what spring and buffer you’re running right now?
He sure can. Of course, to get the most use out of his new rifle, he’ll need one of these:
Only if the gun has the short piston. The long piston and the longer gas tube will conflict otherwise.
OH Lord… :eek:
Does anyone remember that thread here… where the guy claimed to have put a gas block and middy tube on his carbean barrel and it blew the top handguard off when he shot it?
I thought for sure it was a joke… 
I do remember that thread. I think there were even pictures.
So the idiot really did this huh? :lol:
I believe he did. If memory serves me right he just swapped the gas block and tube, but not the barrel, and actually fired it and blew off the hand guard. I’m trying to search for the thread but am having no luck.
Yep. Then he got banned. One of our members said they were embarrassed for him, I think it was Bimmer, and the dude fucking exploded saying he was going to shove his now properly working carbine up Bimmer’s ass, and all kinds of insanity.
It was nuts.
Edit - I don’t remember pics, but he said he moved it all forward with a mid length tube then it was a single shot that would pop his handguard off.
When I read your first post that thread came immediately to mind. I was going to reference it, but that’s already taken care of.
As I recall it he was 100% serious and got seriously bent out of shape at another member here in that thread.
It wasn’t EuroDriver, it was Bimmer.
For everyone’s enjoyment.
https://www.m4carbine.net/showthread.php?t=72733&highlight=embarrassed
Yup that’s the one, thanks for the link. I stand corrected, no pictures, just someone asking for pictures.
That’s right!
Oh my god.
That was good for my daily moment of humor!:suicide2:
Back to my nap, now. zzzzzzzzzzzzzzzzzzzzzzz
Couldn’t stop laughing… that is insane.
Wow simply amazing. Glad I knew better when I was just wondering the same thing.