I'm not new to AR's, but In the process of building my first AR. It will be a mk18 clone pistol, and future SBR.

I've got everything planned except the gas block, as there are so many out there and not sure what i'm looking for. Would I need a $70 one or would a $35 be fine?
Even doing the build on gunstruction narrows it down a bit but there are still many options.
Rail: Daniel Defense Mk18 RIS II
Barrel: Rainier Arms Select 10.5"
Gas tube: Spikes carbine length

What would be a good gas tube compatible with this setup? I've been leaning towards Geissele.

Why not use buy a complete mk18 upper from daniel defense.

About the same price.

http://aimsurplus.com/catalog.aspx?search=mk18

Any low profile gas block should work. I'd just get a rainier brand to go with there barrel.

I'd go with an adjustable one if you plan to add a suppressor later.

I've already got all the upper parts on hand that I purchased in the course of a year, minus the gas block and tube. I have an AAC 51T blackout muzzle brake to put on there and for future suppressor use, so I guess an adjustable one is in order.

Nice.

Definitely wanna go with a adjustable gas block. I also would get one with a set screws instead of clamp on. I would dimple the barrel and use the set screws. Imo this is superior to a clamp on.

Great choice on rail and barrel length. Should be awesome. I always wanted a mk18 like yours!!!