Let's clear up the common misconceptions on the AR platforms using Beowulf and the 6.5 Grendel!

 (Before we begin, I can set you up with an upper in all calibers, from 9mm to .50 Beowulf. We have examples of each in the shop. Don't let your AR experience limit you to .223 or 5.56, you can even go AK 7.62 if you want. All we need is your mil-spec lower. No modifications required!)

Are Beowulf and 6.5 Grendal upper receivers compatible with my AR-15 lower receiver?
This is by far the most common question we receive. The short and easy answer is "Yes, absolutely." All Beowulf and 6.5 Grendel upper receiver assemblies will fit on and be compatible with any standard-specification AR-15 lower receiver. No fitting or modifications are needed. If your lower receiver is made to standard AR-15 specifications, all Beowulf and 6.5 Grendel upper receivers will work perfectly. Make sure your lower is mil-spec. You should contact the manufacturer to confirm this.
Will my .50 Beowulf or 6.5 Grendel upper receiver require me to replace the buffer or buffer spring with something heavier/stronger/different/better?No, replacement of the buffer or buffer spring components is not required as long as the lower receiver is made to standard specifications. Buffer components should not be replaced if they are already standard. Please review the first Compatibility question. Both the .50 Beowulf and the 6.5 Grendel weapons are properly designed to work specifically with standard-specification lower receiver assemblies containing standard-specification components. It is a common misconception that weapons with higher-than-average recoil, such as the .50 Beowulf, automatically require a stronger buffer spring or heavier buffer to compensate for higher recoil in some way. This is not true of properly designed weapons. The AR-15 buffer and buffer spring are used only for the cycling of ammunition inside of the rifle. Recoil in an AR-15 rifle is almost entirely unrelated to the buffer components, especially with .50 Beowulf. You can thank the 1,300 MPH projectile exiting the other end for the recoil. Lets  talk  a little more about the .50 Beowulf and why you need an upper in this caliber; .50 BEOWULF | THE MOST FUN AR-15 CALIBER Gearing up to take your AR-15 to the range? If you're looking for a sheer adrenaline rush every time you pull the trigger, know that every round isn't created equal. The most common choice is an AR-15 in the standard .223/5.56 NATO. It’s sufficient when it comes to stopping power, you can shoot it accurately to about 300 yards and best of all, it’s inexpensive, allowing you to get more practice in without going broke. But there are many other calibers out there for the AR-15, and even though I love .223 ammunition, I’d be lying if I said it was the most fun to shoot. That honor goes to a round with some serious stopping power – the .50 Beowulf.

A 400-grain .50 Beowulf cartridge hits 1,800 feet per second, making it one of the slower AR-15 cartridges. It hits with a mammoth 2,878 foot-pounds of kinetic energy, and it drops 50 inches by the 300-yard mark. This is definitely a short-range round intended for close-quarters combat, as its maximum effective range is about 200 yards, and it’s more fun to shoot between 50 and 150 yards.

First, a few words of warning about shooting .50 Beowulf rounds from an AR-15 – it will be very loud, meaning you better not forget to put your hearing protection on. Expect the recoil to be heavy, as well. Of course, the noise and the recoil are both part of the fun. Shooting is always an exhilarating experience, but that’s even more true when you’re firing shots that can punch a hole in a truck. If you just want a gun to shoot at the range, an AR-15 in .50 Beowulf will provide plenty of excitement, and you’re sure to get people’s attention while you’re there. You may have people coming up to you asking what you’re shooting. If you’re planning to go big game hunting in the near future, .50 Beowulf is an excellent choice, because you won’t find many, if any, animals that can survive getting hit with one of these cartridges. The obvious drawback with this caliber is that unless you’re fortunate enough to have a limitless ammunition budget, you won’t be able to shoot as much. Prices for .50 Beowulf cartridges are over $1 per round and can even be over $2 per round, depending on what you choose. One way to save a little more money for that ammunition is by choosing a more affordable AR-15 model. And one of the benefits of going with .50 Beowulf is that you can still use the same magazines that you would with .223/5.56 NATO ammunition; you’ll just have a much lower capacity. The only parts you need to swap out to turn an AR-15 chambered in .223/5.56 NATO to one in .50 Beowulf is the barrel and the bolt carrier group. You can also simply purchase an upper receiver to swap onto your lower and make it easier.

I’m obviously a .50 Beowulf fan, but what’s nice about the AR-15 is that you can find a caliber to fit what you want to do with your rifle. If you want top-tier performance from a short-barreled rifle and less noise when you fire your gun, .300 BLK rounds will be just what you need. For long-range shooting, 6.5 Grendel and 6.8 SPC are both effective to almost 500 yards. Personally, I prefer other rifles for long-range shooting, and when it comes to the AR-15, I appreciate pure power. That’s why when I want to have fun and I have some cash to spare, I go with .50 Beowulf.