An Engineering Marvel

Introduced in 1936 and reigning as America’s premier centerfire rifle until discontinued, the pre-’64 Winchester Model 70 was advertised as the “Rifleman’s Rifle,” and indeed it was.

Using a single, standard length action, it was introduced in 18 different chamberings, ranging from the diminutive .22 Hornet to the .458 Winchester Magnum. In my mind, the most unique — and actually the most expensive standard model to manufacture — was the .22 Hornet, although Winchester never charged a premium for it.

From 1936 to 1952, the year it was dropped from the line, 20,306 Model 70 Hornets were produced. How many still exist today in the original chambering? We don’t know. Hunters demanded more power as new varmint cartridges were introduced, and the M70 Hornets were handy platforms for .22 centerfire conversions.

The famed gunmaking firm of Griffin & Howe readily converted scores of Hornets to .222 Remington. More recently, I came across a gunsmithing shop buying up .22 Hornets and converting them to .204 Ruger. Ah, the horror, the horror …

Adapting An Action

Adapting the action and the bolt to the dimensions of the diminutive Hornet involved some brilliant engineering.

The standard, double-column M70 magazine was a simple brazed sheet-metal box holding a machined follower and folded flat spring. For cartridges shorter than the .30-06, a spacer was added to the rear of the box.

In the Hornet, a separate, small, double-column, magazine assembly was manufactured and fitted inside the standard magazine box. This inner assembly contained a Hornet-proportioned follower powered by a music wire spring.

The assembly is slanted forward to separate and properly stack the rimmed Hornet cases. To ensure trouble-free feeding, the front of the assembly sports a long feed ramp that mates with — and blends perfectly — into the standard feed ramp of the action. The assembly holds five cartridges.

The separate Hornet magazine assembly is secured inside the standard magazine box with projecting tabs. The rear of the standard box is itself modified to carry a long, spring-loaded, ejector arm that functions normally through the face of the Hornet bolt. Overall, the Hornet magazine is an elegant but complex assembly that successfully feeds the little cartridges without a hitch.

Adapting the full-size bolt to the Hornet case proved even more complex. Starting with the bolt face, the standard .30-06-type bolt face measures 0.483″. For the Hornet, the face had to be machined to 0.356″. Similarly, the width of the standard extractor claw had to be reduced from 0.407″ to 0.247″. Like all M70 extractors, the face of the miniature claw was beveled to allow the extractor to snap over the rim of a chambered case.

To pick up and feed the rimmed Hornet, a unique spring-loaded cartridge pusher was added to the bottom of the bolt. The cartridge pusher pivots up and down and scoops up the rimmed case from the inner magazine, feeding it into the bolt face and up under the extractor claw.

The next engineering issue to be solved was how to limit the bolt throw of the full-sized bolt to the overall length of the Hornet cartridge, which measures at its maximum, 1.723″.

The solution was what Winchester did to control bolt throw for 18 different cases. They added a bolt stop extension to the bolt, attached to the extractor collar and lining up with the left locking lug. The length of this extension controlled bolt throw when the extension hit the bolt stop as the bolt was opened. Bolt travel for the Hornet was extension-controlled at 2.98″ (for the .375 H&H it was 4.58″).

Finally, the engineers came up with a unique answer to headspacing the little rimmed case. The Model 70 breech was coned like that of the ’03 Springfield. Rather than counter-boring the cone, which they thought would cause feeding problems, they set headspace by having the front edge of the rim just kiss the cone.

The End Justified The Means

A few thoughts about my own Model 70 Hornet. It’s a heavy rifle, weighing 8 lbs. 14 oz. un-scoped and 9 lbs. 11 oz. when mounted with a period Lyman 6X All-American. While handloading for it, I discovered it preferred 0.223″ Sierra Hornet bullets rather than 0.224″ versions. The answer turned out to be the groove diameter of Winchester Hornet barrel is a tight 0.222″.

Does it shoot? Because of its excessive weight, I haven’t hunted with it for years, but my old handloading data based on Remington cases and 7.5 primers, Winchester 680 powder and those Sierra bullets records 3-shot, 100-yard groups running from 1/4″ to 1/2″ with an average velocity of 2,588 fps from the rifle’s 24″ barrel. In its day it was a great jackrabbit and coyote gun.
So there you have it — the story of probably the most unique and complex Model 70 ever assembled.

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