Foster type rifled slugs

This is a short, blunt lead bullet that is solid in front and hollow in the rear, analogous to a badminton bird. And, like a shuttlecock, it is its weight forward balance that allows the Foster slug to fly through the air to its target with reasonable accuracy. Compared to lead balls, this was a big improvement in both accuracy and SD.

Heavy external "rifling" was cast into these Foster type slugs, allegedly to allow the air they flew through to impart a slow spin that would help stabilize the slug. Like most something for nothing schemes, the rifling proved ineffective, but it did provide some space for some compression if the slug had to squeeze through a tight choke. The name "rifled slug" stuck and is still in widespread use today.

Rifled slugs are offered by most of the major ammunition makers in a variety of shotgun gauges, including 12, 16, 20, and .410 bore. They used to be made under bore diameter to allow safe passage through any degree of choke, from full to cylinder. Cylinder bore guns are usually recommended for shooting slugs, but in some cases a full or modified choke barrel will give better accuracy with the undersize slugs.

This may not always hold true these days, however, as Remington advertises that their "Slugger" rifled slugs are made oversize for better sealing against the barrel wall and superior accuracy. Compared to rifle bullets, whose diameter is held to very strict tolerances, Foster type slugs are made to rather haphazard dimensions that vary from one manufacturer to another.

The use of slugs is best confined to single barrel shotguns, either single shot or repeaters. Double guns tend to crossfire with slugs due to the regulation of the barrels.

A smoothbore "slug gun" with rifle sights will usually shoot groups in the 3" (6 MOA) range at 50 yards/meters, making them satisfactory short range deer guns. An occasional example will do better, and some do worse. Shooting groups from a bench rest with a slug gun is not fun, as the recoil is considerable.

Compared to practically any big game rifle bullet, rifled slugs are still "penetration deficient," and not very accurate. They are a short range proposition at best and should be reserved for use only on CXP2 class game. The ballistic coefficient (BC) and sectional density of rifled slugs is pretty pitiful. If possible, always use a rifle in preference to a slug gun for any kind of big game hunting.

Some jurisdictions in the U.S. forbid the use of rifles and mandate the use of shotgun slugs for deer hunting, allegedly for "safety" in crowded hunting areas. I am sure that this is what keeps rifled slugs viable as a sporting proposition. (They are also used in police "riot" guns, of course.)

This is actually kind of funny in an ironic way, as the one thing slugs do really well is penetrate brush. Rifled slugs are probably the most dangerous type of ammunition to use in a wooded area crowded with hunters, as they plow through visually impenetrable brush, leaves, and small tree limbs with aplomb. A high velocity rifle with a frangible bullet would be far safer in such an environment. I have, for instance, seen .22 varmint bullets fired at very high velocity turn into a puff of blue smoke on a blade of grass!

Conventional Foster type rifled slugs generally weigh 1 ounce in 12 gauge, 4/5 ounce in 16 gauge, 5/8 ounce in 20 gauge, and 1/5 ounce (or 87 grains) in .410 gauge. The 12 gauge slug has an advertised muzzle velocity (MV) of 1560 fps from a 2 3/4" high-brass shell, 1680 fps from a 2 3/4" Magnum shell, or 1760 fps from a 3" Magnum shell. These are Remington figures from their 2004 catalog. The MV's of the other gauges are similar.

The catalog energy figures for the common high-brass ("maximum") 12 gauge slug load are an impressive 2361 ft. lbs. at the muzzle, but only 926 ft. lbs. at 100 yards. This is due to the very poor BC of the slug. Sighted to hit dead on at 50 yards, that slug is 4.8" low at 100 yards. The more powerful 12 gauge slugs are only marginally better, and kick noticeably harder. No matter what, rifled slugs remain a very short range proposition.
Only 12 gauge slugs should be used for deer hunting. In fact, the reason for producing rifled slugs in the other gauges escapes me. Despite their fearsome diameter, 12 gauge slugs are mediocre killers beyond 100 yards, and the smaller gauge slugs are much worse.

The 20 gauge slug develops only 931 ft. lbs. of energy at 50 yards and 648 ft. lbs. at 100 yards, which given its low SD is not encouraging. The pathetic .410 rifled slug is generally inferior in both projectile weight and terminal performance to the lowly .380 ACP pistol cartridge--often despairingly referred to as a "mouse gun." The less said about these sub-12 gauge rifled slugs the better.



Brenneke, Buckhammer, and Trophy Slug

These resemble Foster type slugs with one important difference: the wad remains attached to the base of the slug. This provides a better BC and stability in flight, a better shuttlecock, if you will. The assembly is heavier than a plain rifled slug due to the weight of the attached wad. The difference in retained energy at 100 yards is considerable.

The original design of this type, as far as I know, is the German Brenneke slug, offered by Rottweil. Brenneke rifled slugs still use felt and fiber wads, and are suitable for use in smooth or rifled shotgun barrels. Rottweil offers several slug loads in 12, 20, and .410. Their 2 3/4" 12 gauge slug weighs 1 1/4 ounce, and their 3" Magnum 20 gauge slug weighs a full 1 ounce.
A MV of 1476 fps and ME of 2538 are claimed for the 12 gauge 2 3/4" Magnum load. More important is the 100 yard retained energy figure of 1170 ft. lbs.

Fiocchi of Italy offers the Aeroslug Trophy Slug, which appears to be a modernized and simplified version of the Brenneke design. It, too, is recommended for both smooth and rifled barrels. The Fiocchi Trophy slug weighs 1 ounce in 2 3/4" 12 gauge shells, and 7/8 ounce in 2 3/4" 20 gauge shells. Ballistics are similar to the Brenneke loads with somewhat less energy due to the lighter slugs.

Perhaps the most creative design of this general sort, with which I am familiar, is the Remington Buckhammer. It is also the most recent innovation. The Buckhammer lead slug itself is a short truncated cone, rather like a lead "Keith" style revolver bullet. Attached to the base of this is a long, plastic "stabilizer" wad. Remington says that the Buckhammer was designed for use in fully rifled barrels, or with rifled choke tubes. The diameter of the lead slug is supposed to be .73", so I do not see why it could not be used in cylinder bore (smooth) shotgun barrels, but I have not tried it. Experiment at your own risk!

12 gauge Buckhammer slugs weigh 1 1/4 ounces in 2 3/4" cases or 1 3/8 ounces in 3" cases. 20 gauge Buckhammer slugs come only in 2 3/4" cases and weigh 1 ounce.

These Remington Buckhammer loads claim the most impressive ballistics of the bunch. The 12 gauge 2 3/4" load has a MV of 1550 fps and ME of 2935 ft. lbs. The 100 yard figures are 1145 fps and 1600 ft. lbs. Zeroed at 50 yards, the 1 1/4 ounce slug should hit 3.6" low at 100 yards, so it is still a short range load.

The 20 gauge Buckhammer load has a MV of 1500 fps and ME of 2236 ft. lbs. The 100 yard figures are 995 fps and 1074 ft. lbs. Zeroed at 50 yards, the 1 ounce slug should hit 4.6" low at 100 yards.

While still very inferior to the 12 gauge loads, the Buckhammer and Brenneke slug loads (which claim similar ballistics) at least get the 20 gauge slug gun up off of its knees. If I had to shoot a smoothbore 20 gauge slug gun, these are the loads I would use.

All three manufacturers of these "super" rifled slugs claim exceptional accuracy in fully rifled barrels. Remington, for example, claims 3" to 3 1/2" 5-shot groups at 100 yards (3.5 MOA or better) with their Buckhammer slugs.

http://www.chuckhawks.com/shotgun_slugs.htm