5 Alternate Rounds to Use for Your Next AR Build

By: Casey Callison

I think just about everyone is familiar with the common AR platforms: The AR-15 in 5.56 (.223) or the AR-10 in 7.62 (.308). These are the common chambering options for an AR and for good reason. They’re reliable rounds, the ammunition is available in bulk almost everywhere, and they’re what the military uses. While these are great reasons, there are also other calibers available to build an AR around.

5.) 7.62×39


While this isn’t the sexiest round to be considered, it is very reliable. Most people would argue that this is an inaccurate round, but I would disagree. Most of the time when this round is shooting poor groups, it’s because it is fired from something like an SKS that hasn’t had a proper cleaning in over a decade. The SKS isn’t the most accurate rifle no matter how it is chambered. Sometimes the round can’t be blamed. I have shot a few different ARs chambered in 7.62×39 that would actually surprise you with their accuracy. Another bonus: the ammo is dirt cheap (which is one of the main reasons I included it in this list)!

4.) 6.5 Grendel


The 6.5 Grendel is a fun round that you won’t find many people at the range using, but it is a phenomenal alternative to the .223. It is a slightly larger diameter at .264” and has a much higher ballistic coefficient. They are also far superior to the .223 if you are shooting over 200 yards out of your AR. This is also a very affordable round that you can find for less than a dollar per.

3.) 300 Blackout


300 Blackout is another unique, enjoyable round to shoot. This is a good option if you wanted to go with a 30 caliber bullet through your AR. The other fun part about this round is that with certain rifles, you can shoot both subsonic and supersonic out of the same rifle without having to change anything. A lot of people consider this to be a great home defense round since it can be subsonic and is made for use with shorter barrels. As with the other options listed, this is also a very affordable round to be had.

2.) 6.8 SPC


The 6.8 SPC and the 300 blackout are often compared. However, the 6.8 SPC is a great round out to longer ranges. This round is a very proven round even out to 700 or 800 yards. It is a smaller round at .277”, but still very powerful for the size. The only downfall is that you cannot use standard AR magazines for this round. However, it more than makes up for that shortcoming in performance and price per round.

1.) 6.5 Creedmoor


Of course. The 6.5 Creedmoor at the top of this list. I think everyone paying attention to ammunition over the past few years could have seen it coming from a mile away. Coincidentally, this round has been proven to reach out to a mile! The absolutely incredible ballistic coefficient of this round makes it an obvious choice. While it isn’t the absolute best long range round out there, I feel like it is the best round that you can make a unique AR out of. This round is the most expensive of the previous rounds, but the reliability is incredible.

BONUS: .224 Valkyrie


While I wanted to include this in the list, it is just too new of a round to have proven itself. The ballistic coefficient makes it superior to the .223 while being able to use the same basic platform for your AR. This means you could switch over to the .224 Valkyrie with minimal effort. This is an up-and-coming round that is definitely one to keep an eye on!

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