My first AR build - upper questions

[slowmo]

I am working on my first AR build and have a couple questions as I am trying to decide what I want for an upper. I know I want a 16" barrel. So:

1: What is the difference between a carbine gas system and a mid-length gas system. I know that carbine is shorter, but I am wondering why I would choose one over the other?

2: If I were to get a carbine (even a mid-length gas system), it is my understanding that I would be able to put a low profile gas block so that I can put a longer, free-float handguard on it. If this is true does this affect sighting at all? Is this going to change the height of my front sight vs a milspec sight or using a gas block with a rail on it?

Thanks in advance for your information, advice and guidance.

 

[shooter521]

1: What is the difference between a carbine gas system and a mid-length gas system. I know that carbine is shorter, but I am wondering why I would choose one over the other?

It is widely held that the mid-length gas system smooths out the recoil impulse and reduces wear on the bolt carrier assembly. It is also claimed to be more reliable, but I've never had an issue with my carbine-length systems either, so I can't speak to that directly.

If I were to get a carbine (even a mid-length gas system), it is my understanding that I would be able to put a low profile gas block so that I can put a longer, free-float handguard on it.

That's certainly an option, though I prefer a fixed front sight base unless the gun has a magnifying optic.

Is this going to change the height of my front sight vs a milspec sight or using a gas block with a rail on it?

No, assuming you get a flip-up front sight of the correct type (there are some made to go on railed forearms, and others made specifically for railed gas blocks; obviously there is a height difference between the two).

 

[r6vr6]

Shooter521 pretty much hit it. A fixed FSB is quite a bit cheaper than your other options generally but may not be as flexible as you want depending on what kind of optics your planning on running. For me if I have any optic I am going to want some kind of folding sight.

Another thing to consider is the "weight" of your barrel. Yes you are going with a 16" barrel but do you want lightweight, midweight, HBAR, bull etc? These will dictate rail and gas block options too. I have an hbar and a midweight and I wish they were both mid but that wasn't an option at the time for the manuafacture I wanted. So think about what you want to use the rifle for and then pic the appropriate weight barrel.

 

[slowmo]

Thanks guys. Thanks for reinforcing what I thought I understood.

 

[Unoid]

Go with a FSB, You can also Cowitness or use a riser/different mounts to make your optic sit higher.

The only reason I see it useful to cut out the FSB is for AR-15 PISTOLS.

 

[SavageEagle]

I've got a .22lr upper coming in with a YHM Free Float Rail. Obviously it doesn't need a gas block so I opted not to get one. I did, however, order a set of UTG fixed front and rear detachable sights to use with no optics. It's a .22 so why would you need optics, right? Anyway, the ones I bought are these....

ARR-140 - AR-15 Leapers UTG Complete Rear Sight Mounts on all Flattop Rails
ARR-108 - AR-15 and M4 Leapers UTG Detachable Front Sight Sight Assembly and Integral Picatinny Mounting Deck

I'm not so worried about height as I am if they will align right. I plan on taking the gun to an Appleseed Shoot whenever the Cav Arms Lower gets in.

My question is basiclly the same as his. Will this setup be ok on my Spikes Tactical .22lr Upper?