What Type of AR Should You Build?

Rise Armament 315c Series Rifle

For better and worse, there’s not a firearm more diverse or flexible than the AR-15 platform. 

For better, what you build can fulfill a mind-boggling amount of roles, from plinker to precision, from SPR to SBR, all by swapping out your upper and other parts, and pairing it with your registered lower.

For worse?  The dilemma you might find yourself facing trying to lock down what exactly you should build.

There are so many barrel profiles and lengths, stocks, sighting options, and increasingly, calibers…its enough to make your head spin.

So…just what are your basic options? 

First off, please understand extreme flexibility means it’s perfectly acceptable and normal to end up with a hybrid.  Nothing you read below is set in stone.  

You Do You

A key takeaway is build what you want, not rigidly clone someone else’s build.  This is important.  Too often, we do things for others…As you sit down and plan, make sure you’re doing this for you, not to wow your friends at the range or online.

The best way to plan is to focus on what your needs are.  What are you going to be using this firearm for?  Hunting (big game…medium or varmints?), competition target shooting, range toy, impressing your friends, or self-defense? 

All are valid options, each demanding something different.

Narrowing the uses of the firearm will help get you locked in on what caliber and dimensions your build will be, and from there, you can start your design process.

A Few Basic Builds

I confess…almost every time I’ve attempted to build some of the basic rifle types listed below (other than my SBR), I end up tossing in something that makes it more of a mutant. 

That’s OK though.

Again, this is about doing things the way you want it – not following rigid examples that may or may not suit your needs.

Basic Carbine

These are ideal, simple builds for when you want a gun that can do most everything reasonably well while being easy to handle and compact.

This is the gas system I’ve used on 14.5” guns or shorter…

A modern carbine complete upper receiver from Aero Precision.  This model is the M4E1-E Complete Upper, 14.5″ – MSRP – $425.00

Basic Mid-Length

Same as above.  Different gas system making it a bit softer shooting.

With a longer handguard due to the 16” and 18” barrels you usually see mid-length gas systems paired with, you might find it more controllable.


If you’re toting around a rifle all day, or have other reasons to desire a lightweight rifle, then it would be wise to start your build thinking about a lightweight profile barrel.  

Don’t let the term “lightweight” give the wrong impression.  Many modern barrels like the BA Hanson are still plenty robust while keeping weight down.  As Clint Hanson from Ballistic Advantage says of his barrels:  “Lightweight feel without the lightweight limitations.”

Ballistic Advantage BA Hanson Midlengh Performance
Ballistic Advantage 16″ 5.56 BA Hanson Midlength Performance Series Barrel w/ Pinned .750 Lo Pro Gas Block – MSRP – $230.00


Most REECE (recon) clones I’ve seen are mid-length 16” standard or lightweight builds with a collapsible buttstock, topped off with a 1-4x, 1-6x optic or something similar.  The term “Mini-REECE” can also be heard from time to time…indicating a slightly shorter 14.5” or even SBR length 12.5”or 11.5” barrel lengths.


Built for accuracy, 18” stainless steel barrels are found on Special Purpose Rifles, whereas DMRs often have a 20” barrel.  Quality optics are important here.

As a reminder with this or any build, when building YOUR Special Purpose Rifle, just remember to tailor it to your special purposes, not someone else’s.  To see what a classic SPR looks like, I’d recommend diving into the history of Crane’s Mk12.

SBR/Pistol Builds

M4e1 7.5" 5.56 complete upper
Aero Precision M4E1 Threaded Complete Upper, 7.5″ 5.56 Barrel – MSRP – $359.99

Short Barreled rifles have barrels starting at 14.5″…with other common 5.56 lengths coming in at 12.5”, 11.5”, 10.5”.  For calibers like .300BLK, these barrel lengths come in even shorter, with 8” and 9” varieties commonplace. 

My current personal home defense gun is an 8” 300BLK SBR with a Rugged Razor suppressor.  These are ideal trunk/truck guns, ideal for personal protection, etc…but more than anything though, these guns just look really, really cool.

Just remember, with an SBR build, all NFA rules apply…meaning a $200 tax stamp needs to be budgeted for, as well as some extra time.  As such, more and more builders are dabbling in AR pistols.


For every scenario imaginable, there’s an AR for that.  Get a handle on these basic types of rifles and then see which one fits you.  I’d advise doing a deep research dive on the style that is calling to you…Just don’t feel tied down.  As always, if you have any questions, we are more than happy to help.

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