Proper lubrication of working parts - Rifleman

Guns Magazine, Jan, 2003 by Dave Anderson

Firearms are simple machines requiring proper lubrication. The thought of two dry metal surfaces scraping together grates on my nerves like fingernails on a blackboard. This is especially so where parts are under heavy load.

Most bolt-action rifles are designed to cock on opening. The nose of the cocking piece engages an angled surface on the rear of the bolt body. As the bolt handle is lifted this angled surface cams the cocking piece back, compressing the mainspring.

These cam surfaces are quite small, and the powerful mainspring provides a heavy load. When these surfaces are dry, or worse yet, covered with dust or dirt, the effort required to lift the bolt is increased considerably, as is wear on these surfaces.

Bolt locking-lugs and their recesses are another example of metal-to-metal contact under load. As the bolt is lowered, the rear surface of the lugs engage the locking lug recesses and move the bolt slightly forward to fully chamber the cartridge.

A Little Dab 'II Do Ya

To minimize wear and ensure smooth operation, these contact areas need proper lubrication. For this purpose, a modern high-tech grease is preferable to light oil.

I like syringe-type applicators that put a quality lube right where it's needed. Kleen-Bore TW25-B grease is available in a syringe, as is Wilson Ultima Lube.

With these high-quality lubes there is no need to overdo it. Just a dot of lube on the cocking cam and on the rear surface of each bolt lug is sufficient. If the rifle is used in dusty conditions, the bolt should be cleaned and re-lubricated regularly.

Locktime -- Design Priorities

In any rifle action, designers have to make choices that reflect their priorities. Mauser 98 military actions are sometimes criticized for their slow lock time -- that is, the interval from when the sear releases the cocking piece to when the firing pin strikes the primer.

A fast lock time is desirable from a viewpoint of practical accuracy, since it allows less time for the muzzle to move after the trigger releases the sear. This is especially important when firing from unstable positions such as offhand.

The slow lock time of the Mauser is not a fault but a deliberate design choice. Reliability and speed of fire were considered more important than minor increments of accuracy. The Mauser used a heavy cocking piece/firing pin assembly and a fairly light (by current standards) 19-pound mainspring.

The lighter mainspring made the M98 bolt easier to manipulate rapidly from the shoulder, while the heavy firing pin assembly assured positive ignition.

Reliability is important in sporting rifles but so is accuracy, while speed of fire is usually less important. As the bolt-action evolved from a military to a sporting rifle, designers began to introduce "speed lock" designs with faster lock times.

A More Modern System

The original Winchester Model 54 was similar to the Mauser, in that the firing pin had a fairly long travel (about 1/2 inch) and slow lock time. About 1932 Winchester introduced the "speedlock" feature on the Model 54.

It used a lighter cocking piece/firing pin, a more powerful (23 pound) mainspring, and shorter firing pin travel (about 1/4 inch). The same speedlock, with an improved trigger, was used on the subsequent Model 70.

The popular Remington 700 has a fast locktime, provided by a lightweight cocking piece/firing pin, short travel and strong (24-pound) mainspring. The downside to these actions is bolt lift is somewhat harder due to the stronger mainspring that must be compressed.

It is important to understand there is a relationship between cocking piece/firing pin weight and mainspring strength. The designers achieved what they felt was an optimum balance, and it is risky to change that balance unless you know what you're doing. Fitting a heavier mainspring will shorten locktime and maintain ignition reliability, but might add vibrations that affect accuracy.

Hotrodding

It's common for gunmakers building sporting rifles on old Mauser actions to fit a lighter cocking piece assembly and/or install a stronger mainspring. Shooters who want even faster lock times, such as metallic silhouette competitors, sometimes fit even lighter firing pins and heavier mainsprings to current models.

Brownell's catalogue lists kits designed by champion rifle competitor David Tubb, which include titanium and aluminum/steel construction firing pins that weigh about half of factory standard. They come with extra-strong Wolff replacement mainsprings. The kits are available for a large variety of popular bolt-action rifles.

These kits provide very fast locktime, and are popular with silhouette shooters who require accuracy from the offhand position. Bolt lift is increased, but for this purpose speed of fire is not a priority. Extra-heavy "Blitzschnell" mainsprings by Wolff are also available from Brownell's for a variety of bolt actions.

FOR MORE INFORMATION CONTACT:

Brownells, Inc.

[641] 623-5401

www.brownells.com