The following information on the Mauser 98, Gewehr 98, and Kar. 98K comes from Chapter 20 of Mauser Rifles and Pistols by W. H. B. Smith. Mauser Rifles and Pistols is also available to purchase in print.
(Note: Mechanically these are practically identical, as are sporting Mausers in general).
Mauser 98. German Infantry Rifle. Right Side View With Action Closed: This rifle is the prototype of all modern Mauser rifles. It introduced the feature of an extra or third lug at the rear of the bolt cylinder. This lug engages in a recess in the cylindrical part of the rear of the receiver to act as a safety factor in the unlikely event of the two locking lugs behind the cartridge case head letting go. Another added feature of this design, and of the commercial 1904 and later pattern rifles by Mauser, is a small rib on the right side of the bolt cylinder which serves as a guide in withdrawing the bolt. When the bolt is closed this rib lies underneath and supports the extractor. The bolt face is recessed to receive the base of the rimless cartridge. The arm as shown has the full 30-inch barrel length of the true rifle, the Gewehr 98. This arm was also made as a short rifle with a 24-inch barrel, and also as a true carbine with an 18-inch barrel. The most modern Mauser rifles manufactured differ from this type only in such details as length, sights, furniture, and such modifications as were desirable for mass manufacture from stamped parts during war conditions. World War II Mauser and Mauser System rifles, as well as all Sporting Mausers, are derived directly from this rifle. Mechanical differences are inconsequential. This is a basic design.
The German army, which had been using the Gewehr 88, adopted on April 5, 1898 the improved form of the Mauser rifle listed as “Gewehr 98.” This arm was also introduced in short length as a carbine. In 1905 these rifles were bored to give larger groove diameter for the new “S” bullet.
In 1908 a further modification was introduced which was patterned after our 1903 Springfield to combine the features of rifle and carbine. Its length was intermediate between the two earlier forms. This was officially listed as the “Kar. 98.” This type was widely used by the Germans in World War I; and again with only minor modifications it served in World War II as the “Kar. 98K,” and “Kar. 98K42.”
Mauser 98. German Infantry Rifle. Right Side View Of Receiver With Action Closed: While this weapon as shown bears the trade mark of Waffenfabrik Mauser, the arm may also be found stamped with the names of the various German manufacturing arsenals
The original “Gewehr 98” had a heavy rear sight. When issued with a somewhat lighter rear sight, it was classed as “Gewehr 98A.” These rifles weigh 9.5 pounds, measure 49.25 inches overall, and have a barrel length of 29.15 inches. Gew. 98 was the primary World War I German rifle.
The caliber is the standard German 7.9mm but uses a new form of pointed bullet with higher velocity and generally improved ballistics. (When originally introduced, however, this arm used the standard M. 1888 cartridge. Adoption of a pointed bullet required increasing bullet diameter and groove diameter).
Mauser 98. German Infantry Rifle. Right Side View Of Receiver With Action Open Ready For Loading: Note the third locking lug directly ahead of and below the bolt handle and also the long rib bolt-guide on the bolt cylinder in line with the bolt handle. These are special features found in all late model Mauser designs. The date 1907 is year of manufacture. The bolt bears the receiver serial numbers. Other parts bear the final 2 digits, showing original factory checking and assembly
It is rifled with 4-grooves of .0065 inch depth, concentric, with a twist of 1 turn in 9.39 inches, to the right. Sights are the standard barleycorn front and the leaf rear graduated from 200 to 2000 meters.
When the Spitzer (pointed) bullet was introduced the ballistic requirements of the new bullet, which was shorter than the round nosed, required an increase in bullet diameter from about .318 inches to about .325 inches. Representative ballistics will be found herein.
Mauser 98. German Infantry Rifle. Top View With Action Closed: The cutaway section at the front of the metal receiver bridge across the rear of the action provides a guide for insertion of the loaded clip. As the bolt handle is turned up, its lower end where it faces the cylindrical bridge section of the receiver moves against the inclined plane to provide the leverage necessary to loosen the cartridge in the chamber and provide primary extraction. Thus as the handle is raised, its bearing against the plane (or cam) surface on the receiver bridge compels tile unlocked bolt to pull back away from the face of the cartridge chamber.
The Evolution of the Kar. 98
The Kar. 98 underwent no change of any kind from 1908 to 1916. In 1916 a hole was bored through the stock and provided with a bushing. This hole which has been characteristic of all Mausers of military type since that time, serves several purposes. It was originally designed to permit passing a locking rod through the sides of a rifle case, and through the holes in the butts to secure cased rifles for shipment and storage. It was later used as a resting point for the striker in dismounting the bolt to prevent injury to the point. During World War I it served as a special mount for a trench periscope.
Mauser 98. German Infantry Rifle. Right Side Phantom View Showing Action Open Ready For Insertion Of Loaded Clip: Note that the left side of the receiver above the magazine way is cutaway. This is to provide clearance for the thumb as it pushes cartridges down off the clip into the magazine.
In 1907 finger slots were provided below the rear sight to permit a firmer grasp with the fingers.
During World War I various models of sniping rifles were made, many using 20-shot box magazines, and some equipped with bolt covers. The essential mechanical design, however, has not changed; and most important operating parts are interchangeable.
Mauser 98. German Infantry Rifle. Right Side Phantom View With Arm Ready To Fire: Four cartridges remain in the magazine. After the cartridges are stripped down out of the clip, thrusting the bolt forward knocks the empty clip out of the guide lips and chambers the top cartridge, leaving four in the magazine. As already described in the Spanish Model 93, by easing the bolt forward over the top cartridge while holding the magazine cartridges thrust down with the thumb, it is possible in this design to insert a sixth cartridge in the chamber. If loading is done directly by the bolt however, only 5 can be inserted. Note the third (safety) lug locked into place to rear of magazine well.
The “Kar. 98,” the “Kar. 98K,” and the “Kar. 98K42” are practically identical. They differ only in minor points of construction or in manufacturing processes.
They weigh about 9.5 pounds, measure about 43.5 inches overall, and have barrels of about 23.4 inch. Rifling is the same as in the Gewehr 98.
German ordnance chart showing all details of Mauser 98. The mechanism of this rifle is similar to all later Mausers. While some of the parts are stamped and others forged, mechanically they are practically identical. Description of basic Mauser design on pages 121-128 essentially covers all Mausers made since 1898. (Click to Enlarge)
The foresight may be blade or barleycorn with a V-notch radial rear sight.
The descriptive and operational data on pages 121-138 substantially cover all Mauser models wherever made after 1898. Specifically that data is based, however, on the Mauser 1924 series; the pattern was evolved from the Gew. 98 after World War I to increase efficiency and permit mass manufacture.
Belgium, Chinese, Czech, Polish, Portuguese, Spanish and Yugoslav “Mauser System” manufacture is practically identical with the German.
German ordnance chart of the last Mauser model. Mechanically it is the same as the Gewehr 98. All Mauser and Mauser System rifles wherever made since 1924 are based on the above design. This differs from the World War I 1898 design in having a broader gas flange; a magazine follower which holds the bolt open when last shell is ejected, different sights and stock. It is also shorter. Mechanically all are nearly indistinguishable. (Click to Enlarge)