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How To Build Your Own Custom 7mm PRC

Have an old rifle that could use an upgrade? Here's a step-by-step process for building your own custom rifle.

How To Build Your Own Custom 7mm PRC

Last season I had the opportunity to take a rifle chambered in 7 PRC to the field for some pre-launch testing chasing aoudad down in West Texas. Being a long-time fan of .270/7mm calibers, I was itching for the chance to see if Hornady’s latest cartridge would live up to the hype. In short, after shooting at the range, taking a great ram and seeing the praise the cartridge has received over the past year, I’m confident in saying this hot, new 7mm is here to stay.

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After the season wrapped up, I knew what my off-season project would be – building a semi-custom 7 PRC of my own. After reading Joseph von Benedikt’s article at RifleShooterMag.com, I figured it wouldn’t be that difficult once I acquired the components. Back in February, I started to put in orders for the necessary parts to complete my own semi-custom 7 PRC.

The Parts

First things first, I wanted to use an action I had on-hand. I’ve owned a Weatherby Vanguard in 7mm Rem. Mag. for close to a decade and it would be the perfect, cost-effective way to get started on what would be my first semi-custom rifle build. Next, I would need to find a new barrel properly chambered with the desired 1:8 twist rate. During the aoudad hunt, we shot rifles with CarbonSix barrels with great success; their reliability and capabilities made them a natural fit.

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Next, I would need a new stock to house these components to create a rifle that was lightweight, yet didn’t kick like a mule. I found Peak44 to be a great option and put in an order for their Bastion carbon-fiber stock. To top it off, I got in contact with Silencer Central to start the paperwork for one of their new Banish Backcountry suppressors to screw onto the end of the rifle. After putting in all these orders, all I had to do was wait, which turned out to be the most difficult part of building my own rifle.

Fast forward about three months and parts started showing up. From here I found the right gunsmith to help with this project. Being my first time building a rifle, I not only wanted it done correctly, but wanted to gain as much knowledge as possible as we went through the process step-by-step. Luckily a buddy helped by hooking me up with the perfect gunsmith, Caleb Conn from Wyoming.

The Process

The first step was to remove the original barrel from the Vanguard. With most rifles you could do this by placing it in a vise and simply unscrewing the barrel, with the proper action wrench; but with Vanguards specifically, you have to use a lathe to make cut off the shoulder of the barrel where it meets up with the receiver, then it should unscrew easily. Once you’ve done this, the original barrel will be completely unusable.

Once the barrel has been removed, thoroughly clean the entire action, especially the threads inside the receiver. Pro tip: Use a M26x1.5 tap for this (specific to a Vanguard). You’re mainly looking for any burrs, chunks or chips of metal left behind from removing the previous barrel. A wire brush is also very handy here.

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Next, we test fit all of the parts. The new barrel shouldn’t be loose, but you don’t want it tight either; you’re looking for a nice snug fit. You’ll also want to test fit the stock. Caleb calls this a “dry fit.” While performing this, we noticed the stock needed to be slightly altered due to the barrel nut not fully seating. A little elbow grease and file work quickly fixed that.

After the dry fit, we disassembled the parts, and it was time to lap the lugs and receiver. While lapping the lugs, you’re looking for somewhere around 80-85% contact to help ensure greatest accuracy. Caleb then sandblasted the receiver. Being nearly a decade old, the gun had seen its fair share of time in the mountains. We wanted to bring it back to its original finish and give it that “new rifle” look again. Once that was completed, it’s time to get our build on.

Putting It All Together

To assemble the “new” rifle, we first secured the action in a vise and screwed the barrel in. This is done with the bolt removed and a go gauge in the chamber. Then, after replacing the bolt, we screwed the barrel until it stopped with the bolt closed. This helps to give you proper head-spacing for your specific rifle. Caleb hand tightened the barrel nut down until it was just snug and then switched to a no-go gauge, trying to close the bolt several times to be certain it cannot fit within the chamber.

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For the next step, he put a go-gauge back into the chamber, closed the bolt and tightened the barrel nut down completely. The Vanguard action would need to be tightened down to 70 ft-lbs of pressure. Next, we rechecked the head-spacing with the go/no-go gauges. If you haven’t noticed yet, the building process requires a lot of redundancy to ensure the firearm is as safe as possible and the rifle is chambered for the specific caliber.

After double and triple checking the go/no-go gauges, we placed a dummy round in the chamber to see if the rifle would accept the proper cartridge. In our case, the dummy round wouldn’t fully seat, so Caleb broke out a hand-reamer and re-polished the chamber to properly fit the 7 PRC cartridge. We quickly discovered a small bur was preventing the cartridge from seating properly and not allowing the bolt to fully lock into battery. Once the polishing was complete, everything was smooth as butter.

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Next up it was time to bed the stock. Caleb recommends putting the rifle into the vise with the action inverted and the recoil lug facing up. He then went through and coated the front action screw, recoil lug and bottom of the receiver from the barrel nut back to the magazine with a releasing agent; more is better here so coat both sides of the action. Any metal that could touch the bedding compound will need to have this releasing agent on it. Caleb says the releasing agent is cheap insurance if you’ll ever want to disassemble your rifle in the future.

Caleb placed a Q-tip in the threads where the front action screw would go; this acts as a guide and makes for easier cleaning later. As he mixed up the bedding compound, he made sure to mention to always follow the manufacturer’s specifications. This is where more isn’t better. After mixing it up, he showed me where to put the bedding compound in the stock. He recommends placing it between the magazine well and recoil lug, rather than coating the entire length of the stock. He also recommended to only fill the recoil lug cavity approximately two-thirds full.

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We secured the stock in the vise and slowly placed the action into the stock. This is where the Q-tip comes back into play as a guide, ensuring everything sets straight down into place. We were then able to remove the Q-tip guide, making sure to clean as much of the excess of the bedding compound as possible with additional Q-tips.

Next it was time to install the bottom metal and hand-tighten the action screws for the time being. After that’s completed, Caleb checked the barrel to make sure it was properly aligned and sitting straight within the stock. He makes sure to do this now, because it’s not easy to remove after the bedding agent cures.

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After 48 hours, I removed the stock and used a chainsaw file to clean the front-action threads. Caleb insists clearing out any excess amounts of the bedding agent to make sure your action screw is secured in the rifle itself, not the compound. While doing this, I also checked for any air bubbles or gaps. Then I reassembled everything, tightening the screws to 55 in-lbs of pressure in the Peak44 stock.

Finally, it was time to mount the scope. I had a Leupold VX-6HD on hand which would be a nice topper. Using a Peak44 picatinny rail, I mounted the scope and quickly boresighted it. It was time to head to the range, slowly break-in the barrel and see what we did right. We’ll cover that in an upcoming article, but for now I can tell you the results didn’t disappoint.

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Build Specs

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