Building A Custom Mauser Rifle–Part 2

Ken Brooks

by Ken Brooks, AGI Gunsmithing Instructor and
owner of PISCO Gunsmithing in Oregon.

Here is the rest of Ken’s great article on sporterizing one of his favorite firearms. Now get out there and build your own!

If you have built a sporterized Mauser or other rifle yourself and would like to share some photos of the result, send them to me and they will be featured here on Guns and Gunsmiths.


The next step I take with the customer is bolt handle selection. Unless the customer already knows what he wants, I’ll usually use a catalog and let the customer select the handle he likes best. Occasionally I’ll offer a recommendation based on the customer’s needs.


The ’98 bolt, disassembled.


Sights are another item that needs discussion with the customer. There are a variety of options depending on what the customer’s needs are. For example, if a customer intends to have open sights used as a back-up to a scope, then we’ll discuss quick-detach scope mounts. Before we attach scope mounts, we will have to remove the stripper guide from the rear bridge of the receiver. This can be ground, filed, and finish sanded to match the contour of the bridge behind the guide, or it can be ground off on a milling machine using a fixture available from Brownells and others. This, as well as the drilling and tapping of the mount base screw holes must be done prior to the heat treating process.


Safety election can be impacted by the choice of sights. A scope will require the installation of a low-scope safety. The three-position Winchester safety is a good choice. It functions naturally. It also has an attractive appearance, although it takes more work and machining to install.


Triggers can be a very personal choice. It’s best to let the customer choose the appropriate trigger. A number of options are available. Double-set triggers are a classic choice, but if they’re not really needed it may not be worth the expense involved. New England Custom Gun Service, Ltd. and Timney Triggers make great triggers.


The barrel is one of the most important elements of the rifle. You can spend several hundred (or thousand) dollars on the rest of the rifle, but if the barrel isn’t up to standard it’s all worthless.
Douglass and Shilen make good middle-grade barrels. Pac-Nor makes a little better barrel, as well as Krieger or Lilja. I let the customer look and see what he wants. Some customers will only take a Lilja barrel. As a general rule I avoid barrels that sell for less than $100. The barrel is the last thing the bullet touches, so you don’t want to skimp here.

I also prefer to select barrels that are not pre-threaded and short chambered. There can be quite a bit of variation among the different Mauser variants. A pre-threaded barrel may fit one model perfectly, rattle in another, or can’t even be screwed into a third. It also helps with regard to reaming the chamber, as the short chamber may be larger in diameter than your reamer, which can cause steps in the brass that customers will complain about and make you look like a nimrod. Remember what I said about happy customers?


The feed rails and extractor face will both need some metal removal to feed magnum ammo.

The feed rails and extractor face will both need some metal removal to feed magnum ammo.

The stock is usually the last consideration when working on a custom Mauser rifle. I generally recommend a fiberglass stock if the gun is to be seriously hunted with, instead of being a static display piece. They are stable under a wide variety of conditions. Wood can warp, rot, swell or contract after exposure to bad weather; synthetic stocks won’t.

It’s also important to make sure the action is bedded properly. If there’s binding or stress induced in the barrel or action, or the barrel is not allowed to float freely (as a general rule) in the barrel channel, the bullet won’t be exiting the muzzle at the same point in its oscillation every shot. I generally bed the recoil lug and the first two inches of the barrel, then from behind the recoil lug to the front of the magazine. I also bed the sides. It gives the barrel some support as well as eliminates movement of the action in the stock. Then I make sure the remainder of the barrel is free floating.


Reliability is the most important aspect of a hunting, military, or tactical/defense rifle. I would rather have a gun that shot every time but gave me a 5 inch group at a 100 yards, then one that gave me a half-inch group at 300 yards but misfired, failed to extract, failed to eject, or failed to feed EVERY time. Fortunately, Mausers, and military rifles in general, are very reliable. However, there are a few areas that may need to be addressed.

Proper fitting of the firing pin can help with reliability as well as improve safety. Remember that many of these Mauser rifles were in service for many years with many rounds of corrosive ammo having been fired through them. This could erode the breach face, opening the firing pin hole, and eventually pit the firing pin. This could thin the pin to the point it pierces the primer. This has the potential to send primer material back through the firing pin hole, as well as into the shooter’s face. Making sure the firing pin tip is the proper diameter and fitted properly in the bolt face is essential.

I believe that the most important element of the Mauser’s reliability is the extractor. You want to have confidence that the fired case comes out of the chamber, every time, when you work the bolt handle. To do that the case has to stay on the bolt face. The tension has to be properly adjusted to do this. Otherwise it could fail to eject and drop onto the feed rails on top of the next live round. This will most assuredly cause a misfeed and a jammed action.

Of course, the extractor is only part of the equation; the ejector must work properly as well. One thing to remember is that many of these military Mausers were assembled in the field and in depots with mismatched parts, so it’s important to have everything fitted and adjusted properly.

Misfiring is not usually a problem encountered with military rifles. However, it’s still possible to run into a rifle with below-specification springs. In these instances it may be necessary to replace the springs, for example with those made by Wolff Gunsprings.

There is one last thing to consider for reliability, as well as safety. It’s important to properly relieve the receiver when installing the barrel. Maintaining the proper barrel thickness at the shoulder is important to maintain the structural integrity of the chamber, particularly when the rifle is being chambered for a magnum cartridge. If the barrel is too thin in this area, it could lead to the chamber bulging.

Other Considerations

Bolt handle attachment is another thing to consider when developing a project. Some bolt handles are welded while others are soldered. I highly recommend welded bolt handles. They’re stronger and last longer. I consider soldering to be a form of metal glue.

For customers who want open sights, the installation for the front sight is dependent on the planned use of the rifle. I recommend barrel-band sights for their high level of durability. Drill-and-tap and soldering methods are not as strong. If the barrel-band sight is installed properly, it will not come off or get knocked out of alignment. It’s also easier to align during installation. Again, I recommend the products from New England Custom Gun Service, Ltd.

Another thing to consider is whether or not the customer might be requesting upgrades in the future. The customer may need to choose less expensive components now due to budgetary restrictions. Such choices should be made regarding components that can be upgraded later. On a Mauser rifle it may be possible to go with a less expensive trigger, safety, and/or scope and mounts, then upgrade to higher quality versions in the future. Other components, such as the bolt handle and barrel, are not really upgradeable due to the fitting required.

Technically speaking, there are no real limitations on the cartridge length a Mauser can be chambered in. However, the process of chambering a Mauser for a significantly longer caliber than it was designed for, let’s say a .375 H&H, can be a very laborious and time-consuming process, resulting in a potential 5-figure price tag.

Other components, such as sling swivels and muzzle brakes, have fairly straightforward installation methods, so I don’t believe it’s necessary to go into detail in this article.

Final Words

It’s important to communicate with your customer. You need to know your customer’s level of knowledge as well as the purpose of the project. You also have to be able to offer advice when it’s needed and be able to guide the customer to the best possible choices. It’s also important to be honest about the level of investment, in terms of time and money that will be needed.

Remember…a happy customer is good for business.

2 Responses to Building A Custom Mauser Rifle–Part 2

  1. Ken,
    You touched on the length of the cartridge as being laborious but also the diameter of the cartridge. Such as the short fat Rem 7 mm saum i built in a model 48, not sure if you remember the project. It took alot more time than i had in my budget to get this to work for the customer.

  2. Ken,

    Couldn’t you just replace the standard bolt with a magnum bolt in a standard long action large ring Mauser, instead of the need to open up the face of the original bolt?

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