I'm building my first 3 gun rifle and I'm deciding on what to build my upper with.  Has anyone used the Romeo barrel on a build? On the Dynamic Defense website they state: "Compatible with mil-spec BCG and carbine buffer/spring. Do not use with heavy or light buffer weights/springs or lightweight BCG’s as this barrel was designed to enhance the performance of mil-spec rifles without having to use modified components."  How does it compare to using adjustable gas blocks, lightweight BCG's, lighter or heavier buffer weights and springs? I've only found a couple of reviews of this barrel and none of them have done this comparison. I'm a VERY novice shooter but I wanna make a nice build from the start. Am I better off going with an adjustable gas block, lightweight BCG, light or heavy buffer system or going with the Romeo?

OR

Since I'm a newby to the AR platform, does it even matter?

I haven't heard of this particular barrel.

Frankly, if it is ported properly to run with a standard bolt carrier group and carbine buffer, there is no reason you couldn't use an adjustable gas block and then whatever low mass carrier you liked the best.

There is nothing inherent to a barrel (excluding things like that KAC E3 barrel which uses a different bolt lug) about what kind of bolt carrier and buffer you can use, so long as it is properly ported for the ammo you are using.

16" is quite short for a rifle length gas system.  It can work.  But you should be aware that it may turn out to be a fickle setup in scenarios like low powered ammunition, very cold weather, or a very dirty rifle.

Frankly their warning about not using it with different weight springs or carriers is probably an attempt to head off complaints about unreliability from end users who don't know how to properly tune a rifle.  If it will cycle a standard carrier with a standard buffer and spring, there is no reason it won't work with a low mass carrier and an adjustable gas block.

But the window of proper operation is smaller with so little dwell time with reduced barrel beyond the gas port.

For similar money you could get a Stretch16 barrel.  They are marketed to 3 gunners so they won't admonish you not to use competition type operating systems and use an intermediate gas system which will give you the benefits you are seeking from a longer gas system.

I use an 18" rifle gas barrel right now, my replacement barrel is a 16" mid.

An adjustable gas block is a must if you plan to use a low mass carrier.