How To Build a 7mm PRC Rifle: Hunting and Precision Shooting

Looking for a do-it-all cartridge and rifle? Here is how to build a rifle from scratch chambered for the new 7mm PRC.

September 17, 2023 By Keith Wood

The last thing I needed was another 7mm rifle. Between my .280 Ackley Improved, my 7mm Remington Magnum, my 7mm Practical and various flavors of 7x57s, I thought that I had things pretty-well covered in the .284” department. Then came the news that I’d been expecting since Hornady’s introduction of the .300 PRC rifle cartridge; the 7mm Precision Rifle Cartridge was on its way to market. Much has been written and spoken about the 7mm PRC but the gist is that it is what the 7mm Remington Magnum would be if it were invented today. It is my job to keep my finger on the pulse of what’s out there, and besides, I’m always looking for an excuse to buy or build another rifle. A project was born.

The 7mm PRC is based on the beltless 375 Ruger case and designed to be compatible with heavy-for-caliber bullets without crowding propellant capacity. It has minimal body taper, a healthy-sized neck, a 30-degree shoulder and throat specs that should help in the accuracy department. You may think of it as an adult-sized 6.5 Creedmoor. The 7mm PRC’s long bullets can boast high ballistic coefficients, an important factor for the folks shooting at extreme distances. That doesn’t concern me much, but I do favor the terminal performance of these heavy projectiles.

For example, one of my all-time favorite big game bullets is the 175-grain Nosler Partition. I’ve used it on elk, kudu, mule deer, whitetails, and feral pigs at a variety of distances and always with lethal effect. This long bullet is great on game, but it can limit powder capacity in certain cartridge cases. When I had a custom 7mm Remington Magnum built several years ago, I specified a long throat to allow me to seat that specific bullet as far forward as was reasonable. With the 7mm PRC, that would have not been an issue.

On paper, I consider the 7mm PRC ideal for taking typical North American game animals. Perfect for anything from deer to elk and, with appropriately designed bullets, capable of taking larger species such as moose and the big bears. It would do great on African plains game, as well. The bottom line is that I’m a 7mm fan, and if you made me spec-out my ideal cartridge for hunting western game, I would land where Hornady did on this one.

I wasn’t among the writers who got the chance to try out the 7mm PRC before its public announcement, so I had some catching up to do. Ammunition was being made, but few rifles were available, meaning that building one would be the most expeditious route. If everything came together on schedule, I would have this rifle ready before the end of Alabama’s months-long 2022 to 2023 deer season. I began scrounging components for this build, and the Hornady folks were kind enough to ship a reamer kit my way.

This would be a hunting rifle built with precision rifle DNA, so I chose my components accordingly. These days, actions, barrels and stocks can take months to acquire, but I was fortunate enough to land what I needed. I started with a long-action Defiance Deviant Hunter with a magnum bolt face. I’ve used Montana-made Defiance Machine actions on multiple projects and have always come away impressed. Just four miles down the road is another company whose products I use frequently, Proof Research. Proof sent me a 22 inch carbon-fiber-wrapped barrel blank in their Sendero Light contour with a 1:8-inch rifling twist.

I sourced the stock closer to home, opting for a Carbon All Terrain (CAT) made by AG Composites. I had used their stocks on factory rifles but had never built a rifle on one in my own shop. The rigid but lightweight CAT combined the virtues of a traditional sporter with elements of more modern rifles, which was exactly the theme this rifle was intended to follow. For the magazine and bottom metal, I chose a hinged floorplate unit from Hawkins Precision and a Wyatt’s Outdoor magazine box and follower.

With work shut down at my day job for the Christmas holiday, I got after it. After making due with a Chinese lathe for several years, I’d finally acquired my dream machine - a Hardinge HLV-H Super Precision with low miles. This would be my first rifle built on this, the Cadillac of toolroom machines. There are various techniques for holding and dialing-in a barrel and everyone believes theirs to be superior to all others. I stole mine shamelessly from an Australian gunsmith named William Hambly-Clark, who described it in-detail in his book, Centerfire Rifle Accuracy.

Clark’s technique relies on a simple set of gimbals and focuses on holding the barrel with minimum stress while aligning the chamber area of the bore with the spindle of the lathe. Rifle bores are anything but straight but this allows the bullet to engage the rifling in precise alignment, one of the real keys to accuracy. Once we have the bullet started, we don’t really care how far the bore wanders. The muzzle end of the barrel is held using a spider, which I built specifically for this purpose. Using Clark’s methods, I dialed the barrel into the lathe so that the test indicators showed a runout of less than .0001 inch over the length of the chamber. If I’m going to take the time to do this myself, I may as well do it to the best of my ability.

At this point, the chips began to fly. I cut the tenon to fit the dimensions of the action before carefully threading it for the best fit that I could manage. Unlike most manual lathes, cutting threads at high speed on the Hardinge is relatively simple. Carbide tooling behaves better at such RPMs, resulting in cleaner and more precise cuts. Soon, the action was spun onto the barrel and indexed so that the muzzle’s high point was at the 12 o’clock position.

Next, I cut the bolt nose relief and began the slow process of cutting the chamber. The JGS reamer kit that Hornady provided included both a rougher and a finishing reamer and, with lots of high-sulphur cutting oil, the chamber was deepened until it crept up on the headspace gauge. I have found that, with many of the new cartridges on the market, ammunition dimensions vary less than they traditionally did and chambers can be cut to a minimum headspace—this one was no exception.

Once the chamber was polished and the feeding edges were chamfered, I reversed the barrel in the lathe and dialed in the muzzle using the same gimbal method. We want the bullet to leave the bore as squarely as it entered it. Since this barrel would wear a brake full-time, I cut an 11-degree crown before threading the muzzle section 5/8-24. The Thunder Beast Arms 30CB brake spun on and indexed, making the barreled action complete. The AG Composites stock came with aluminum pillars installed so bedding the action with Marine-Tex was straightforward. That process complete, I sent the action to H&M Metal Processing to have the action black nitrided. A TriggerTech Special two-stage trigger was installed to round-out the building process.

A rifle built to these specs requires a scope capable of true precision, but I don’t like excessive magnification on a rifle intended for hunting. With that in mind, I mounted a Leupold Mark 5HD 3-18x44mm optic in 35mm rings and headed to the range. Shooting any new rifle creates plenty of uncertainty but the stress is especially high when you built the entire rig yourself. Am I any good at this? Did I waste all of that time and money on a rifle that won’t shoot? Is this thing going to blow up in my face?

I stoked the three-round internal magazine with the only ammunition that was available at the time, Hornady’s 175-grain Precision Hunter ELD-X. For starters, the new rifle went bang without creating a stress test for my shooting glasses. Thanks to the brake, recoil was minimal. I made some adjustments to settle the zero and carefully fired a three-round group. Through the scope, I could see that the first two bullets went into the same hole, so the pressure was on not to shank shot number three. I settled down as the trigger’s first stage progressed into the few ounces that would send the shot.

The first group out of the rifle was a tight little cloverleaf that measured 0.282 inch center-to-center at 100 yards. The average velocity for those first four rounds was 2,881 feet per second (fps) with a standard deviation of 6.9. Subsequent groups were in the same ballpark. On principle alone, I will do some load development to see if I can improve upon that standard, but there’s no real reason to. This level of accuracy is a great indicator of what can happen when the builder uses premium components and takes the time to build things properly. The combination of this action, barrel, stock, to say nothing of Hornady’s factory ammunition, proved to be extremely capable. Best of all, the complete rifle is very shootable from practical field positions thanks to a well-designed stock and an outstanding trigger pull.

Since its inception, this rifle was intended to wear a TBAC Ultra 5 Gen 2 suppressor. This tiny but capable can cuts recoil and muzzle blast significantly yet adds minimal length to the rifle. Best of all, its mounting system creates repeatable points-of-impact. After a wait of just over six months, the ATF Form 4 was approved, and I was able to pick up the suppressor from my dealer.

The rifle build, minus the suppressor, was complete before my season ended, but the buck that I was after successfully eluded me—they don’t get big by being dumb. This rifle will travel with me to west Texas to hunt desert mule deer this year, which should be a perfect opportunity to use it in the environment that it was designed for. I will get as close as my stalking skills will allow but, if a longer shot is necessary, I know that my rifle will be up to the task.

Is the Hornady 7mm PRC all that it’s hyped-up to be? The answer is subjective, but by any measure, it is a well-designed and capable cartridge. Its ability to use heavy-for-caliber bullets without robbing case capacity makes a lot of sense in the practical world, especially for longer-range situations. Think of it as a scaled-up 6.5 Creedmoor. Those attributes, combined with high-quality factory ammunition from multiple sources, should ensure that the popularity of this cartridge only continues to grow—and that’s a good thing.