The .410 slug capable or comical?

Guns Magazine, June, 2003 by C. Rodney James

What use is a .410 slug? Ohio, where I live, is one of those shotgun deer states where .410 slugs have been alternately illegal and (currently) legal for deer hunting. Both Marlin and U.S. Repeating Arms have brought lever-action .410 shotguns to the market, and all our major ammunition companies are loading the .410 slug, so somebody must be using them.

The late Frank Barnes in his book Cartridges of the World makes somewhat contradictory observations about the .410 slug. On page 386 (7th edition), is the statement, "The .410 slug is not good for anything but small game at short range. Yet on page 393, he makes the point that while inadequate for deer, the slugs are quite effective in such guns as the Savage Model 24 combination gun (fitted with rifle sights) and that it is possible to hit rabbit-size targets at 80 yards. He also claims clean kills on bobcats and coyotes at this range.

Accuracy Tests

The Ithaca company did the most extensive development of shotgun slug barrels a number of years ago, and concluded the best accuracy was obtained from cylinder-choked barrels with highly polished bores. Few .410s have true cylinder barrels. For this article I obtained a Winchester 9410 and an old Winchester Model 42 with a cylinder barrel. The 9410 came equipped with adjustable open sights and was set up for scope mounting. The 42 was equipped with a scope mount from Aimtech Mount Systems of Thomasville, Ga Please note this was a special request, and is not offered by Aimtech.

Both guns shared a Burns 4X Mini. In spite of Frank Barnes' optimistic predictions, it soon became evident that 50 yards was about the limit for both of these guns when it came to reasonably precise shot placement. As a "not recommended but legal" deer round, careful shot placement is the only means of taking a deer with a .410.

All three U.S. makes of slug loads were tested and the 2 3/4-inch RWS "Rottweil" Brenneke was fired in the Model 42. The 9410 is chambered for 2 1/2-inc shells only. See chart for the results. Of the American product, the Remington slugs were the best performers in both guns while Winchester was the worst with Federal in the middle.

Since the slugs were all of the Foster type, appearing much the same, the reason behind these considerable differences in group size was a mystery. The most obvious hint was that the dimpled nose appeared off center in many of the Federal and Winchester shells I examined, as though the slug was slightly tipped in the shell. The Remington's flat nose appeared properly centered.

Dissection of sample shells revealed internal differences and a major surprise -- the slugs are not the same diameter. The Remington measured .402 inch, while the Federal was .394 inch with the Winchester at .389 inch. The RWS measured .409-inch diameter.

Scott Grange, of U.S. Repeating arms later confirmed these findings. He pointed out that the Remington slugs are made for true cylinder barrels while the slightly smaller Federal and Winchesters are intended for modestly choked "improved cylinder" and "modified improved" barrels.

Grange mentioned that the accuracy results I obtained were average, though a few of the 9410 shotguns he had tested produced groups as small as 1.5 inch at 50 yards. For exceptional guns of this sort Barnes' 80-yard claims could represent reality.

Anyone planning to do any serious slug shooting in his .410 should have it equipped with sights and target all available makes of ammunition to determine which will work best in his gun.

An Old Debate

Do rifled slugs spin-stabilize in flight? This question has been answered emphatically "yes" and "no" through dozens of articles over the past 50-plus years. I have yet to see any conclusive evidence of the high-speed motion picture variety though. It would seem, however, that both sides hold a certain amount of truth.

The Foster slugs have very shallow rifling and since these slugs obturate in shotgun bores, most of these grooves are ironed out in the process. I questioned an engineer at Federal on this matter and he allowed as how they had done motion picture studies and their slugs did not rotate.

He further pointed out that slugs moving at supersonic speed (which .410s do--top velocity in my tests was 1,930 fps) would be pushing a shock wave, thus creating a vacuum along the sides and would have no air in that area to work on the grooves. He offered no opinions about sub-sonic slug behavior.

Slugs of the Brenneke type, however, have raised helical vanes which are not flattened out and theoretically should catch the moving air and cause the slug to rotate and spin stabilize at sub-sonic velocities. The best anecdotal evidence of this comes from Ray Boos, designer of the Vitt-Boos slug--a modified Brenneke with high, angled vanes.

Boos told of a customer who got a bad batch of slugs which had the attached wads screwed to the bases off center. Accuracy was terrible. The man tried removing the screw and loading the wads behind the slugs unattached. Accuracy was restored and the slugs hit the target front-end first indicating they were spin stabilized without the attached tail wad to act as a steering guide. I recall that there is (or was) at least one European company loading Brenneke slugs in this manner-- with no attached guide wad.