Mossberg Model 151M

The Dawn of Man(nlicher)

The Model 151M was one of these improved products, specifically an improved Model 51M — their immensely popular 15-shot tubular magazine semi-automatic rifle with Mannlicher style stock that first hit the market in late 1939. The “M” in the model designation stood for Mannlicher stock.

A Mannlicher stock runs the full length of the forend and was associated with expensive European hunting rifles. Harold Mossberg understood a great deal of the Mannlicher stock’s extra cost was in the extra-long stock blank required to make it. He patented the idea of using a two-piece stock joined by a simple sheet metal stamping to create a low-cost stylistic facsimile. Consumers must have thought it classed the rifle up, because these stocks remained very popular on the post-war rifles.

The 151M was manufactured from 1946 to 1958. I don’t have hard numbers to back this up, but I’ll bet Mossberg sold more .22 rifles with their faux, two-piece Mannlicher stocks in the approximately 14 years they produced them than the total combined number of all the other sporting rifles sold with real Mannlicher stocks.

The Model 151M had a slimmer stock than the older 51M, a redesigned bolt and improved action with a sturdier firing pin, a new elevation and windage adjustable S-107 rear sight. Most innovative of all were the “V” grooves cut along the length of the receiver’s left and right side to clamp scope mounts onto. This type of scope mount is called a tip-off mount and was very popular on low-recoiling rimfires for decades.

Mossberg pioneered the concept of mounting optics without having to drill and tap the receiver. Not only was this more efficient for the shooter, but it made it easier for Mossberg to sell them scopes as a DIY upgrade.

Other 151M features carrying over from the 51M were Mossberg’s excellent adjustable rear peep sights. They could be attached by screws at two or three different distances from the eye as best suited to the shooter and folded out of the way when open sights were preferred. The high cost of Lyman peep sights was the driving force behind Mossberg developing their own, more economical designs utilizing stamped steel parts to replace expensive machined components. The substitution of stampings for milled parts became common in military arms developed during World War II, but Mossberg was already there. In fact, if you dismount the action from the stock on a pre-war 51M rifle, you’ll see Mossberg was utilizing manufacturing techniques advanced for the firearm industry at the time. Such techniques included heavy sheet metal stampings in the fire control components and welding the machined feed lips to the magazine tube support running through the buttstock.

When it was introduced in 1946, the Model 151M retailed for $30.90, which in today’s dollars is equivalent to $403.24. This was Mossberg’s top-of-the-line semi-auto .22 rifle at a time when semi-autos were notably more expensive than bolt actions. To get a real sense of what Mossberg was offering, we need to compare the 151M to one of its contemporaries, the semi-automatic Winchester Model 74.

In 1954, the Mossberg 151M cost $34.95 and the Winchester 74 cost $39.20. In today’s dollars the $4.25 difference between them equals $46.68. Both were semi-automatic with a tubular magazine in the buttstock, both were equipped with open sights and walnut stocks.