Dumoulin Mauser Barrel Work

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Prior to the COVID-19 pandemic, I got the idea in my head that I wanted a custom rifle built. I got into the project knowing that I would need the help of a skilled gunsmith to attach the barrel to the action. Outside of that, I was confident that I could handle the rest of it on my workbench at home. The first decision I had to make was going to be the heart of the build: the receiver. It seems that everyone and their brother nowadays is building some variation of the venerable Remington 700. Who can blame them?

It is a proven setup and very widely available, including copious amounts of aftermarket support. I did not follow this trend, as I always liked standing out and going against the grain. Hey, fortune favors the bold, right? A quick side note: Should you decide to get into one of these It is ready to be threaded and fitted to the M98 action. custom rifle builds, I commend you! It is a very rewarding task to complete.

Having said that, it is a great idea to get into the mindset that this is your build alone and, therefore, you shouldn’t expect to get the same money out of it that you put into it. It is not likely that anyone will value this as highly as yourself, especially if you go to sell it later in life for whatever reason. This was a hobby project for me, so I went into it knowing it would cost me more than any mass-produced rifle on the market. Well… at least in "pre-pandemic" dollars!

After a quick Internet search, I found that a gun shop near me had factory-new Dumoulin Mauser 98 actions recently put up for sale and at a really reasonable price. To those of you that read my last article ("The

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45 Mauser Mystery", July 2022) can you sort of see a trend with my preferred type of rifle? I called to verify stock before driving the whopping three miles across town and they had some on the shelf still! I don’t even think I properly hung up the phone before I was out the door with cash in hand. Now I know what most of you are thinking… some version of, "Why on Earth would you choose an M98 when the Remington 700 is so much more modern and the current ‘standard’?" I say that building a 700 clone is too easy!

Who knows, I may just be some glutton for punishment. There is just something about the Controlled Round Feed actions that I find so intriguing. Anyway, after forking over $300 and waiting the ten or so minutes for the background check to come back, I was back in my car to head home with the Dumoulin action in hand. This particular model has the dovetailed integral scope mounts, but finding rings to fit them proved rather fruitless. Thankfully, the receiver was drilled and tapped for aftermarket bases.

That same gun shop, SARCO of Easton, Pennsyl- I have an older generation Leupold VX-II 6-18x40mm scope I purchased from a friend specifically for this rifle, but I needed rings to clamp it to the rifle. For this task, I turned to my all time favorites from Warne. Their steel one-inch Maxima rings are, in my humble opinion, second to none. Before I could settle on a barrel choice, I needed to verify what my bolt face was cut for.

As advertised, the factory had machined the bolt face for the standard 12mm cartridge rim. This led me down the path of choosing 25-06 Remington for the chambering, but the bolt face looked physically too large to hold the standard size rim. Out of curiosity, I found a fired case from vania, also had such a scope base on hand. Made by Evolution Gun Works of Quakertown, Pennsylvania, this unit is a one piece Picatinny rail that rests flat on top of the dovetails and uses provided screws to lock it in place.

At the time, in early March of 2019, the EGW rail was $40 plus tax, a very affordable option. my 300 WSM in my reloading components. It clicked in and held through a few shakes of the bolt, but a fired 30-06 case fell out every time. So this dictated that my build would be a The brass lock nut as machined, ready for assembly.

The package includes the screws needed to attach the rail to the receiver. magnum, but the distance between the two receiver rings measured out to be a short action. Already having a 300 WSM, I didn’t want a repeat, but I did want along range round that could also dispatch varmints on my cousin’s farm at a moment’s notice. The 6.5mm bug has bitten me, so this put me at a bit of an impasse. A 6.5mm pill in a short action… what to do? My gunsmith helped me reach a decision of the relatively new 6.5 PRC cartridge.

Knowing what the chambering would be, I now needed a barrel. I originally had my heart set on a pipe from Proof Research, but they didn’t have a barrel with the twist rate I desired at the time. Enter a company called Carbon Six (CarbonSixLLC.com I spoke with their Director of Sales on the phone a few times, and these calls are what sealed the deal with them. I spoke with a Mr. Gene Gordon, and the time he spent helping me through my questions made me feel like I was his only customer that day.

The barrel was now on order, and just about six months to the day it shows up on my doorstep. I ordered the optional muzzle threading to attach a device such as a suppressor or muzzle brake. Getting a suppressor, as you all know, is a royal pain in the backside and I do want something to tame the blast at the business end of the tube. I had a chunk of stainless steel on my workbench. So I measured the threads on the barrel, 5/8"-24 x 3/4" long, and drilled the bore 1/32" over the diameter of the bullet.

I turned a taper to go from the one-inch muzzle diameter to the outside diameter of the existing stock and then milled the two opposing sides flat. I then drilled the cross holes from each side, and after that, threw it in the CNC mill to hog out the two pockets and put healthy leading chamfers on them. I plugged the threads to keep out the grit and to protect them, then proceeded to sand blast the entire unit to give it a matte finish in the pockets, holes, and on the rounded sides.

I then lapped the two opposing flat surfaces, as well as the threaded end and business end. I followed this up with some automotive chroming polish and voila! Nearly mirror-like finish contrasted with the matte sandblasted finish that matches the barrel. I would just need to source a Belleville washer to attach and time the brake. Now to bring all the parts together into a nice package that will shoulder well. I needed a stock. This is the one part that I spent the most time researching, hands down.

Sparing you all the gritty details, I made the final choice of a Boyd’s Hardwood "At-One" adjustable stock. All the benefits of a Precision Rifle Series-class adjustable stock in a more traditional-looking package. While Boyd’s does a phenomenal job at inletting the stock to fit a multitude of receivers, mine did require final fitting of the action pocket and the barrel channel. Brownells had the barrel channel inletting tool I needed, and that made the task of opening up that channel into child’s play.

The action pocket, both top and bottom sides, were the more time-consuming fixes. With the Boyds At-One Adjustable Gunstock, the forearm is a removable part held on with two machine screws threaded into bushings mounted in the underside of the barrel channel. As a result of cutting more out of that channel, I needed to sink those bushings a little deeper into the wood. A 7/16" drill bit did a fantastic job of sinking those bushings deeper.

I very gently advanced them to the desired depth to clear the barrel and still lock the forearm back onto the stock. Another quick side note: If you don’t currently have a rotary tool of some sort, do yourself a favor and invest in one! On to the action pocket. The Dumoulin I purchased was a little wider at the front ring than a standard M98 large ring action. I needed to open up the area for the front ring ever so slightly. The recoil lug pocket needed some attention as well.

The pocket was a little too small, and the recoil lug didn’t fit at first. With some careful attention, and a gentle hand guiding my rotary tool with a wood burr attached, I cut away small amounts of wood until the recoil lug seated properly. Since the Model 98 came in so many variants at the height of its use, Boyds will not cut the bolt channel on the corresponding side. The end user, me in this case, had to do this. Around wood rasp took care of this task.

I gently placed the action into the refined pocket and attempted to close the bolt. It went 90% of the way, but that last 10% was the finite detail work that needed to be done. With the use of a Sharpie marker and that round wood rasp, I gradually took one or

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two passes at a time until the bolt closed all the way without hitting the wood of the stock at all. I then took 400 grit sand paper to round off any ragged edges of the wood. The Dumoulin action from SAR- CO comes from the factory with a useful adjustable trigger setup, but the trigger pocket is only cut for a military style trigger. The pocket in the stock needed to be elongated to prevent interference with my trigger squeeze.

As for the bottom portion, the fitting work for my rifle was equally split between the stock itself and the receiver’s bottom metal. While the hole spacing was spot-on, the forging was slightly oversized both fore and aft. I carefully marked and ground off a little bit at a time until it was a "drop-in" fit. This particular action also comes equipped with a swinging floorplate in the FN or Ruger style. When you open said floorplate, there is a little finger that moves up as the floor swings away.

Most 98s do not have this feature, so the stock does not have a relief cut into it near the front action screw to accommodate the finger. Fitting a spherical wood burr to my rotary tool and cranking the speed to its maximum, I carefully carved out a pocket just big enough for the finger to move about freely. My receiver came with a rear pillar that needs to be installed in the stock. A 3/8" drill bit opened up the rear action screw hole nicely. The pillar measured 0.380" in diameter so it pressed in perfectly!

With my intention being along range/varmint rifle, I purchased the upgraded attachments for the grip panels for this stock. This includes a more vertical hand grip, the beavertail-style forearm (which includes two sling swivel studs, one for the sling and a second one for the attachment of a Harris bipod), and a section of three-slot Picatinny rail on the toe of the stock under the buttstock for the attachment of a monopod. Above and Speaking of a monopod, I needed one.

However, because I didn’t feel like spending what amounts to a miniature mortgage payment just to have one, I decided to make one. I had some old worn out Weaver scope rings sitting in a parts bin. Being able to mount to a Pictatinny rail, I had my clamp! I had a length of oneinch hex stock leftover from a job, a chunk of one-inch diameter freemachining brass, and a short length of 3/8" threaded rod all within arm’s reach.

I faced the threaded rod to five inches long, faced one side of the hex stock square, turned a radius on the other end, and drilled and tapped each end. One end was for the 3/8"-16 threads and the other end for 1/2"-13 to accept a set screw that I turned to a point. I turned the brass down a little bit on one side, then drilled and tapped for the 3/8" threads and knurled the outside for grip.

I needed away to clamp the assembly to the rifle, so I fixtured the beat up Weaver ring in a milling machine and machined off the half ring until a useful flat surface resulted. With that done, I ran a chamfer mill around all four cor-

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ners and then found the center of the new surface. After drilling and tapping for the same 3/8" threads, I inserted the threaded rod with some red Loctite. The next step was threading on the brass lock nut and then treading the pointed set screw into the hex stock, point out, until it stopped and torqued it into place. This is designed to be a wear part, to be replaced should it get worn. After threading the hex stock onto the allthread, it was done.

I had a complete home- I will still need to glass bed it in place. Below center: The front ring/recoil lug pocket after opening it up to fit my receiver. made monopod for the cost of my time. All that said and done, and my wife surprises me with nice folding monopod on Christmas morning! So I am now keeping my custom made rig on standby and attaching the one she gave me. As a result of cutting away some of the bottom metal forging, the protective finish was also cut away.

This had to be rectified to prevent corrosion of the bare metal. A Birchwood Casey bluing kit was just the trick! I used the solution in the kit to removed any old finish and got the bottom metal down to bare steel. Hint, a little extra metal prep before the bluing goes such along way to getting headturning results. I had some Scotch-Brite pads laying around on my work bench, which paired with a spray or two of WD-40 and some elbow grease yielded a gorgeous polished surface for refinishing.

Denatured alcohol was used to clean away any remnants of oil, grease, and bits of Scotch-Brite pad bits off of the metal. The resulting bluing looks like a factory job! Now to glass bed and assemble this entire project. For that, I will get my hands on some Acraglas from Brownells. Thanks for reading, and I hope this article helps anyone looking to do their own finish work on a custom build. Special thanks go to Evolution Gun Works, SARCO, and Brownells. AG