Why do some have them and others dont?Atleast i assume this because i cant see one on my Wilson UT-15 or my colt preban?

The front site tower is the gas block on you’re guns

101 posts, but you do not understand the gas system on your rifle? You are definately in the right place. You will learn everything you ever needed to know here!

Bob

i a couple months we will have you rebarreling uppers.

good point AR15 for fun,but i had to ask.I always have known the gas tube runs to the front sight ,its just that any time a manufacturer refers to their top end or complete rifle like DPMS or ARMALITE for example, that has a standard front tower or a cut off one like on my UT-15 or a GG&G front flip up on my preban no one mentions gas block,but on  anything with the big round  bolt ones or the ones that have a picatinny gas block, are always mentioned as if its different in some way. For example JP ent says their ajustable gas system is a off shoot of the recoil eliminator and can be ajusted or shut off to tune your bolt velocity.Hence my confusion.So does this mean all gas blocks are ajustable?

"So does this mean all gas blocks are adjustable?"

No, all gas blocks are not adjustable...