Gen II Solo 300 .350 Legend Uppers

June 10, 2025

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If you ever wanted a manually operated AR, then you need to check out Solo 300. Their uppers are great for states that don’t allow semi-autos for hunting. They make great suppressor platforms, too. As the name implies, they started out with .300 Blackout uppers. They now have a variety of .350 Legend models as well.

If you aren’t familiar with the Solo 300, it’s an upper receiver that fits on any standard AR lower. What sets it apart from other AR uppers is that it’s a straight pull, manually operated design. There’s a slot cut on the left side of the receiver and a protruding bolt handle. The bolt handle screws into an abbreviated bolt carrier group (BCG). The BCG is cut down since you don’t need the mass like you do with a semi-auto AR.

This also means that it achieves its full length of travel within the upper receiver. No buffer system necessary. You can throw a Picatinny adapter on your build. This allows you to add a folding brace or stock depending on your barrel length. As a result, you can put together a very lightweight and compact build with a Solo 300 upper. I have a .300 Blackout build with a 6-inch barrel used as a suppressor platform with my Griffin Sportsman Ultra Light .36.

The system is pretty simple. When you cycle the bolt handle, the standard AR bolt rotates and unlocks just like it would when cycling in a semi-auto. If you had a round or empty case in the chamber, it extracts and ejects it. When you push the bolt forward, it strips a new round out of the magazine and rotates the bolt, locking it in place.

Early Solo 300 uppers like mine were modified standard AR uppers. They had the slot for the bolt handle milled out in the side. There was also a plug that filled in the charging handle slot in the upper, since you don’t use a charging handle with this design. Newer uppers, including the new .350’s, use a Gen II design that’s a dedicated upper for the Solo 300 system. My original style works fine, but I will say the new uppers look pretty clean.

The Solo 350?

Okay, they’re still actually Solo 300’s, but the most recent addition to the line is chambered in the Winchester .350 Legend. I’m a fan of the round and have a few rifles chambered in it. It’s a straight-walled case that uses .357 caliber bullet weights ranging from 124 grains up to 280 grains. Recoil is 20% less than a .243, and considerably less than a .450 Bushmaster or 12-gauge slug. The .350 has 20% better penetration as compared to a .243 as well.

The effective range is about 250 yards. At 200 yards, it still has about 900 ft lbs of energy, depending on the load, versus around 600 ft lbs for a .223, 780 for a .30-30, or 790 for a .300 Blackout at the same ranges. The heavy loads work great with a suppressor, too.

The Solo 300 .350 Legend uppers come with either 10 or 18-inch barrels. The 10-inch models have been around for a little while, but the 18-inch rifle length is new. All of the Solo 300 barrels are threaded and come with a thread protector. You can get them with just a barrel nut for an ultra-light presentation, or with various lengths of MLOK rails.

Options include a bright stainless barrel and bolt handle or a black barrel and bolt handle. There’s also an option for an FDE upper with a black barrel and bolt handle. Prices range from $449.99 to $559.99, depending on barrel length, handguard choice, and finish options.

Extended Bolt Handles

Another newer item from Solo 300 is the option for extended bolt handles. The one minor gripe I had with my Solo was that I’d sometimes rap my fingers on the lower’s bolt release when cycling the action. I felt like a longer bolt handle, or one kicked up at an angle, would help alleviate that.

Well, Solo 300 is on it and now offers that in a couple of options. You can get it in stainless or black Cerakote. You can also buy the standard length in both colors, as well, if you want to swap out. It comes with an attachment screw and rubber o-rings that you can add for an improved gip. Prices are a very reasonable $21.99 for the extended handle.

Is a Straight Pull AR for You?

So, do you really need a straight pull AR? It depends. If you like to hunt with an AR platform but can’t use a semi in your state, then it’s a great option. You can make a very handy and lightweight hunting build with a Solo 300 upper. It lets you use your existing AR lower, too, so you don’t need a whole new gun either.

.300 Blackout does a good job on a lot of game, and the new .350 Legend options give you more punch. Between them, they’ll handle anything from predators, hogs, and deer, up through black bears.

I mentioned earlier, too, that the straight pull action works great with a suppressor. Since it’s designed as a manual action to begin with, you don’t have to worry about subsonic loads cycling the action. You also eliminate any action noise while firing.

I’ve used my Griffin suppressor with the .300 Blackout, and it works great, even with the short barrel. I’ve also used the Griffin on 16-inch .350 Legend rifles and have been very impressed with how it performs. It’s soft shooting and very quiet.

I can see a .350 Legend Solo 300 in my future, as well as the extended bolt handle for my current upper. When I get one, I’ll be sure to post an update here on GAT Daily!