Hornet, Where Is Thy Sting?

Some years ago, I bought a custom .22 K-Hornet on a BSA Martini action with a Winchester Model 43 barrel. It came with a small supply of K-Hornet brass of indeterminate age. I shot a few rounds, then sent the rifle off to have new iron sights fitted. Events overtook me, and the rifle sat in the vault for several years. Recently, I pulled it out, loaded some new Winchester Hornet brass to blow out and started researching loads.

There is little new reloading data for the K-Hornet. The Sierra manual has some, which helped. Beyond that, however, I was left with Phil Sharpe's Complete Guide to Handloading (3rd ed., 2nd rev., 1953), some Lyman manuals from the 1940s and '50s and a couple of Speer manuals from the same era.

It is amazing to me that the ballistic experimenters from the 1930s emerged with their fingers and eyes intact. I have found in the past that some of the published loading data from that era are far hotter than I care to play with. I used some of Sharpe's .22-250 loads at one point and found myself with stuck bolts, pierced primers and one blown primer--and that was with one of his midrange loads.

I put it down to an overly tight chamber (this was a modern rifle, set up for maximum accuracy) and left it at that. After that experience, however, I never take Sharpe at face value: I check, cross-check and check again.

The K-Hornet is reputedly the first instance of a wildcatter blowing out a case to create a new cartridge. Lysle Kilbourn, a New York gunsmith and contributor to the Lyman manuals, put the "K" in K-Hornet, so one would think the data in Lyman books from the early '50s would be firsthand and rock-solid.

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But there are a number of problems with the K-Hornet, a legacy of its parent case. First is bore diameter. Early Hornets were created with barrels of either .223 or .224 diameter, but some were even larger or smaller. I slugged my rifle's bore and found it to be .2225, so I stuck with jacketed .223s from Sierra. For blowing out the cases, I used .224-diameter lead bullets.

Then there is standardization. Kilbourn defined the K-Hornet, but, as Sharpe points out in an obscure corner of his 726-page tome on reloading, it was a loose definition.

At this point, I should mention that Sharpe's book went through three editions, and the third edition had several revisions. Instead of updating sections, Sharpe added supplements with their own indexes and page numbering. In the edition I have, data and vital information relating to the Hornet and K-Hornet are contained in three separate sections with no master index reference. It is easy to overlook critical information--and I did.

Regarding standardization, Sharpe mentions that Kilbourn changed his dimensions a few times and points out how important it is to be sure loads are tailored to your specific chamber. With this in mind, I started with Sharpe's loads and checked and rechecked them against Lyman, Speer and Sierra figures to arrive at what I considered modest, midrange starting loads.

At the range, one load of Alliant (Hercules) 2400 gave me a very sticky lever, another of IMR4227 pierced a primer, and still another of Hodgdon Lil' Gun gave a chronograph reading of an astounding 3,026 fps, a blown primer, a rush of gas over my trigger finger, a blown breech plug and a rifle out of commission.

So what happened? I knew I had a tight bore and allowed for that. My chamber dimensions were not wildly different than Kilbourn's original. As usual, Phil Sharpe had the answer, but it was buried away in a mountain of words.

In the .22 Hornet section of the book's supplement (but not in the main section) was a blunt warning from both Hercules powder and Winchester ammunition, warning that changes to the Hornet case had made old reloading data downright dangerous.

The warning from Winchester, for instance, described complaints of pierced primers and expanded pockets and said its testing of loads recommended by Sharpe in earlier editions had delivered pressures as high as 61,900 psi, where the recommended level for the Hornet was 40,000 psi.

The reason? The Hornet cases had been strengthened."These contain extra metal," Sharpe wrote. "Since the outside of the case must be held to dimensions to fit chambers, the additional metal must be on the inside, thus reducing case capacity. To cram the old charge into a smaller case naturally will increase pressures. Don't do it!" Thanks, Phil.

And, in the same section, a warning from Remington that its new 91„2 primer was hotter than those made before the war, and those using it should cut their powder charges back "a couple of grains."

Tight bores. Varying chamber dimensions. Less case capacity. Hotter primers. Any one of these can boost pressures to unholy levels with even modest loads. To give Sharpe his due, the warnings were all there, hidden away. It would have been nice if he had at least flagged them in the main section on reloading the Hornet.

When my K-Hornet Martini comes home from the gunsmith, it is back to the drawing board.