Seeking AR upper advice

[Wannabe Alchemist]

I am building my first AR15s. I want both a rifle and a carbine. While the lowers were extremely simple to assemble, the uppers appear to require more knowledge.
I am lost on the terminology and requirements. What is the difference if any between "mid length" and carbine? What parts have to be matched for either length, such as buffer, buffer spring, gas blocks, barrel styles, etc?
I realize it's a huge question, but y'all have huge brains!
THANKS!

 

[gregkl]

Mid-length is probably referring to the gas system. Carbine, mid-length and rifle are your 3 gas operating system lengths. This is determined by where on the barrel the gas port is and where your gas block/FSB sits. Gas blocks need the ID to match the OD of the barrel where the gas block sits.

You need to match the gas tube length with the system you have chosen. As a starting point, I would match the spring and buffer with the system also. There are others way smarter than me that can talk about different buffer weights, springs, etc to "tune" the rifle. I have always kept it simple and matched everything.

Then there is the deciding on gas length system as it relates to barrel length. Common is to use carbine length gas with 16" barrels, mid-length with 18" barrels and rifle length with 20" barrels. But there are other options. My current build is an 18" with a rifle length gas system.

You can find a lot of reading online and on this forum. Good luck.

 

[Jeremy1066]

I think midlength gas systems are more common than carbine gas systems these days on shorter 14.5-16" barrels and for good reason. The 14.5" & 16" rifles with a midlength gas system shoot much "softer" than their carbine gas counterparts. Add in a heavy buffer like the Spikes ST-T2 and you a have a rifle with virtually no recoil.

 

[Jeremy1066]

OP, what are your intended purposes for these two rifles? This will help us to make suggestions on things like gas blocks, barrels, etc.

 

[Wannabe Alchemist]

In reality, I hope they'll both only be plinkers. But they need to be ready to defend both long and short range should the need arise.

 

[Jeremy1066]

In reality, I hope they'll both only be plinkers. But they need to be ready to defend both long and short range should the need arise.

Are you planning on using magnified optics? Red dot? Iron sights?

 

[NyleRN]

I think midlength gas systems are more common than carbine gas systems these days on shorter 14.5-16" barrels and for good reason. The 14.5" & 16" rifles with a midlength gas system shoot much "softer" than their carbine gas counterparts. Add in a heavy buffer like the Spikes ST-T2 and you a have a rifle with virtually no recoil.

I've found that a mid-length gas system with an H2 buffer is the bees knees

 

[BDS JIN]

just get a BCM complete upper, problem solved, you will never regret.

 

[Wannabe Alchemist]

I appreciate the info, guys.
I am new to almost everything AR. I'm thinking iron sights, but open to ideas.
Buying a complete upper would defeat part of my purpose. The goal is obtaining the rifle, but building it myself is important to me.
My primary intent would be home defense out to 100 yards.

 

[NyleRN]

I've always told guys to buy a complete rifle or a complete lower/upper for the first time and then tinker around with it in order to get to know the platform. You'll want another one anyway, so the second one build from parts. Not to say you can't build your first one from parts either

 

[gregkl]

NyleRN, good advice.

For me being very mechanically inclined and a student of all things I want to learn how to do, I have yet to buy a complete rifle. I'm on number 3 build now and don't see that I will ever buy a complete rifle. I can build them exactly the way I want it for less than I could buy one configured the way I build mine. My experience is that I save around $200 building my own.

 

[edporch]

just get a BCM complete upper, problem solved, you will never regret.

Or buy the parts from BCM and build your own.
I've been very happy with the quality of BCM parts, and they also ship promptly.

 

[Wannabe Alchemist]

Just an update. The first one is complete and test fired. I went with a Wylde 16" barrel, mid-length gas system, with a rail gas block and iron sites. It recoils a tad hard but livable. I have to learn more about optics before upgrading. LOVE the firearm.

Project two is well underway lacking only the upper receiver, BCG, and hand guard. It will be A2 style with a military surplus 20" rifle barrel.

 

[seedubs1]

Not this snake oil crap. Skip the Spikes ST buffers. They use a powder, and the reciprocating mass doesn't do it's job properly. Stick with Mil-Spec buffers. They operate properly. If you want to read more about it, there's a LOT of reading dis-proving the Spikes ST buffers. They're snake oil.

I think midlength gas systems are more common than carbine gas systems these days on shorter 14.5-16" barrels and for good reason. The 14.5" & 16" rifles with a midlength gas system shoot much "softer" than their carbine gas counterparts. Add in a heavy buffer like the Spikes ST-T2 and you a have a rifle with virtually no recoil.

Depends what barrel length. That's my recipe for my 16" ar, and it works well for me. Just tune to have the heaviest buffer that reliably cycles your weakest ammo. Decide on your gas system based on cork time.

I've found that a mid-length gas system with an H2 buffer is the bees knees

They're good uppers, but if he's wanting to build, he should build it himself. It's the best way to get to know everything about your ar. Plus, if you have any mechanical intuition at all (righty tighty / lefty loosey), it's pretty dang easy. Plus, in most cases, you can build for slightly cheaper and you get exactly what you want. Downside is that resale value will be low if you're into selling your guns (I'll be keeping my ar's, so I could care less).

just get a BCM complete upper, problem solved, you will never regret.