Building the Ultimate Lightweight Magnum

This rifle is designed with hunting in mind, first and foremost–think bear, moose, elk, etc. I wanted it to be lightweight, exceptionally accurate, and capable of doing some extreme long-range (ELR) shooting at inanimate targets past a mile.

What do you get when you build a hunting rig with quality and performance as the only considerations? Read on to find out.

The action is the heart of any good rifle. It’s the part you interact with the most and the foundation for every other piece. When it came time to pick an action, I knew I wanted it to be lightweight, smooth and fully custom.

I was lucky enough to get to tour the Defiance Machine facility here in Montana five years back and was amazed at what I saw. Their attention to detail and the level of precision they put into every action was awe inspiring.

Since my tour, they’ve come out with an action called the anTi-X. A play on words, the action is roughly as light as a titanium action, but made from good ol’ steel. They accomplished this with some clever machine work and lightening cuts throughout. Oh, and it’s über smooth. Like a swiss-made watch, it cycles effortlessly.

There are a TON of good barrels out there. If you’re not “in the know,” navigating the sea of options on the market can be daunting. Drawing upon my past experiences, I knew I wanted a carbon wrapped barrel to shave weight while maintaining rigidity. It also had to be accurate, of course.

There are plenty of options that fit the bill, but only one that comes with a .5 moa accuracy guarantee: CarbonSIX. I’ve used their barrels on other builds and currently run one on my NRL Hunter rifle, and they deliver.

For length, I wanted to keep things short. I run a suppressor and hate carrying a super long rifle. So I went with a 20”, 1:8 twist magnum contour barrel. CarbonSIX sells the barrel as a pre-fit ready to install, and because Defiance machines the actions to such tight tolerances, headspace is guaranteed.

I spent more time selecting a cartridge than I did a barrel and action. I wanted something bigger than the .223, 6.5 Creedmoor and 6.5 PRC I’ve been shooting lately. I wanted something with a lot more punch, that could stay supersonic past a mile, and had excellent ammo availability. I landed on the 300 PRC. Specifically, Berger’s 245-grain EOL factory loaded offering.

After crunching some numbers and talking with a few friends that also shoot that projectile, I figured I could handload ammunition to 2600-2700 feet-per-second (fps) out of the short barrel while factory ammo would probably clock in around 2600 fps. That might not sound impressive, but with the very efficient 245g projectile in my average environmental conditions, it’ll stay supersonic to almost 2,000 yards and carry a 1,000 ft/lbs of energy to 1700 yards. That is legitimately impressive and exactly what I was looking for.

A velocity and energy comparison between a 200-grain .300 Win. Mag. and a 245g .300 PRC.

I first saw an MDT HNT26 chassis at a local NRL hunter match a few years ago. I was amazed at how light it was and how cool it looked. It was different from anything else I’d seen. The fact that it also folded and featured a full ARCA forend sealed the deal. I had to have one.

I purchased the HNT26 for this build, but it didn’t take long to notice one shortcoming. The recoil pad left a little to be desired, especially when trying to tame the recoil of the big PRC in such a lightweight platform. The first time I test fired the rifle, my shoulder was literally black and blue the next day. I had to find a solution.

So, I searched the internet and came across the Back Stop recoil pad. This 3D printed wonder made a HUGE difference. Gone was the harsh recoil kick, replaced by what I’d describe as a “push” to the shoulder. You still feel it, but it’s not painful at all.

Just like barrels, there are a lot of good triggers out there, and I’ve used a number of them over the years. This was a tough choice, but I eventually landed on the Triggertech Diamond. The combination of build quality, weight adjustment range, crisp feel and reputation for reliability in harsh conditions made it a great choice.

So far, it’s been excellent. It breaks like glass and has almost zero creep. I also opted for the flat trigger vs curved. It’s mainly just personal preference, but I’m a fan of flat triggers.

When it came time to pick a scope, I wanted to try and keep it light, but I wanted something with a front focal plane reticle, ample adjustment range and a max magnification power of at least 20x or more. I landed on the Nightforce NX8 4-32, with a MIL-XT reticle. I’ve used Nightforce scopes many times, but they’ve always been on friends’ rifles, so I wanted to try one out for myself. To keep it firmly planted on the rifle, I opted for Nightforce’s ultralight rings. They’re machined very well and mounting everything up was a breeze.

The finished product is exactly what I was after. The rifle, with scope and rings, weighs a mere 8.2 pounds with an overall length of 31 inches when the stock is folded.

As for performance, the results speak for themselves. As you can see from the groups below, the rifle is easily capable of sub ½” groups at 100 yards.

When it comes to ballistics, the 245-grain EOL performed more-or-less as I suspected. Using factory Berger ammo, my average velocity was 2531 fps. Not the 2650-2700 fps I hope to get from handloaded rounds, but the data shows how efficient this round can be. In the charts above, I compared this round to the popular Hornady 200-grain 300 Win. Mag. factory offering at the advertised 2850 fps velocity. You can see that, although the Win. starts off tied or in the lead, it is quickly surpassed in both speed and energy.

This 245-grain bullet is carrying 1000 ft-lbs of energy out to 1500 yards. That’s 600 yards further than the Win. When it comes to retained speed, the PRC will stay super sonic out to 1900 yards to the WIN’s 1300 yards. Needless to say, this setup will pack enough punch for anything I could want to hunt.

First 3-shot group from the rifle: 0.499″.

Another 3-shot group from the rifle, this time with 37 rounds down the tube: 0.487″.

Like I said in the intro, quality and performance were my only criteria for this rifle, which is a nice way of saying that it cost an arm and a leg. A build like this costs north of $5,000, and I’m extremely happy with the results. But you don’t need to spend that much to get a quality hunting rig that will do everything you need it to do. On the same day I was sighting in this rifle, MeatEater’s Garrett Long was also shooting a Sig Sauer Cross Magnum, and it was keeping up just fine.

Still, choosing all the parts and components gives me total control of the final result, and I love the process of building and then tinkering with my rifles. I’ve met all of the goals I set out for this build, but there’s still one final piece of the puzzle: increasing bullet velocity. I plan on working up some hand loads in the coming months to see if I can get 2700 fps out of this 20” barrel. I’ll be experimenting with a few popular powders to see if anything can deliver. Stay tuned for more.