European Heavy Hitter: The Solid Brass USS Slug Tested

June 8, 2010
By Jason Wimbiscus
By Jason Wimbiscus

Two months ago I received an email from who forwarded me the message from European Cartridge Unlimited, a Greece based manufacturer of reloading components, containing information on an interesting new 12 gauge slug called the USS (Ultra Solid Smoothbore).  These slugs, which are currently offered as components for hand loading, consist of a milled, solid brass, flat point projectile encased within and mechanically locked to a stabilizing wad.   The diameter of the bare, brass, projectile is .690″ with a meplat diameter of .510″.  Currently, the slugs are offered in three different weights for three different hull lengths; 570 grains for 2.75″ hulls, 700 grains for 3″ hulls, and 970 grains for 3.5″ hulls.  Being a shotgun slug aficionado, I just had to get my hands on a sample of these heavy hitters.  I emailed the company and they were generous enough to send me a box of their 570 grain slugs to test and review.
The USS Slug loaded into a Fiocchi Hull (Left) and in it’s sabot (right).

According to Eleftherios Vasileiadis of European Cartridge Unlimited, the USS slug was formed to fill a niche in the smooth bore slug market.  In Greece, the only firearms legal for hunting both large and small game are smooth bore shotguns.  Further, the only big game animals that can legally be hunted are wild boar, which are known for being tough and often ornery quarry.   It was felt that existing smoothbore slug technology (which has been fairly static for quite some time) left much to be desired when pursuing boar and other large, dangerous game animals.  These factors ultimately lead to the development of the USS slug.  Although the slugs are currently only offered in 12 gauge, projectiles for 20 gauge and .410 bore are currently in the works.  Slugs for rifled barrel shotguns are also currently in development.

The first challenge in testing the slugs was working up a good load.  Currently, all load data for USS slugs uses a powder called Vectan SP2.  Unfortunately for me, this powder seems to be of limited availability in the United States, so I was on my own as far as load development was concerned.  A quick look at a burn rate chart showed that Alliant Blue Dot has a burn rate similar to SP2, so I decided to use that powder in my trials.  I started with a light charge of 30 grains in a Fiocchi hull, which yielded a velocity of 945 f/s.  The slugs have to reach a velocity of at least 1250 f/s in order for the sabot petals to open up and break away properly.  I gradually increased the charge until I had reached 43.0 grains for a velocity of 1356 f/s from the muzzle of my 18.5″ bbl Benelli Nova.  This is where I stopped.  I’m confident that further experimentation could have yielded higher velocities, but I didn’t want to run myself out of slugs during the load development process and be left without anything to fire into the test block.

Speaking of the test block, this time my approach was different than usual.  Since USS slugs are designed for deep penetration, I wanted to really put them through the wringer.  Rather than using the FBI standard 10% density gelatin, I doubled it to 20%.  In front of this gel block, I placed 1″ of hard polyurethane plastic sheets.  While hard polyurethane does not perfectly mimic bone, it was the best analogue to which I had access that would not reduce the useful life of the gel in the same manner as actual bone.  Behind the gel block, I placed a series of 5/8″ plywood pieces to stop the slug should it completely penetrate the gel block.  In addition to testing the USS slug, I wanted to provide a frame of reference for the results, so for the sake of comparison I also tested a 1 oz Remington Slugger (MV 1421 f/s).
The test setup used for the USS Slug. 1″ of hard plastic, 14″ of 20% gelatin, and a whole lot of plywood.

First, I fired the USS slug into the test block from a distance of 12 feet.  As is evidenced by the photos below, the plastic sheeting was obliterated, the slug completely penetrated the 14″ gel block, and continued on to defeat nearly 2″ of plywood.  The recovered projectile was completely unscathed, save for a few scratches.  Even though I had destroyed my entire supply of polyurethane, I had a second gel block just aching to be used, so I fired the Remington slug into it without the same inch of hard plastic used to test the USS.  The slug penetrated the gel block and dented, but did not penetrate the plywood backer.  The recovered projectile had flattened into a lead disk .85″ in diameter.

top: The test block after being hit with the USS slug.
bottom: The entry hole made by the USS slug

The “wound” channel created by the USS.  Entry is at the right end of the block.

The recovered USS.  Add a new sabot and it could be fired again.

top: “Wound” channel created by the Remington Slugger.
bottom: Recovered Slugger
So far, I’m encouraged by the terminal performance of the USS slug.    I am going to continue working up loads for both increased velocity and optimum accuracy, incorporating different powders, and possibly additional gas seals.  I am also looking forward to testing both the 700 grain and 970 grain versions of this slug, though my shoulder will likely pay dearly for the latter.

For more information on the USS slug, visit the European Cartridge Unlimited website

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