Differential Cover Test - The Great Diff Cover Shootout

Heavy-Duty Covers Make Our Day

From the August, 2007 issue of Jp

By Christian Hazel

Photography by Christian Hazel

This is not a scientific test. This is a buyer's guide with a pulse. We own lots of guns and we like to blow stuff up, so when "diff cover shootout" popped into Hazel's head one staff meeting, the natural progression of things led to flying lead.

While there are lots of scientific variables to take into consideration when determining a bullet's ballistic effect on steel, we ignored virtually all of them. We just took a bunch of guns to the desert and shot at plate steel in varying thicknesses up to 7/8-inch to determine our running order from least to most destructive. Then we called up a bunch of manufacturers and invited them to send a Dana 44 cover for our story. When a bullet rendered the cover no longer usable, either by puncture or deflection, we'd rate it at that caliber. Most companies jumped on board like we were hauling them out of shark-infested waters.

With covers in hand, Hazel welded up a fixture to hold the covers at our 30-yard target distance and Cappa built a 3/4-inch plywood and Lexan shrapnel shield through which we could shoot. At the end of the day, we were left with about 15 pounds of expended brass, 13 worthless diff covers, and the knowledge that we had a whole mess of redneck fun.

Caliber	Velocity (feet per second)	Energy (lb-ft)
1) .22 long rifle	930	69 (sissy little bunny plinker)
2) .45 ACP	850	369 (man stopper, but not a diff dropper)
3) .357 Magnum	1,500	624 (kicks like a mule from the snubby, but doesn’t do much damage to metal)
4) .454 Casull	1,900	1,923 (basically, a Magnum version of a .44 Magnum—a vicious round)
5) .460 S&W	2,200	2,149 (the madman—for dropping bull elk in one shot; one of the fiercest handgun rounds on the planet)
6) 7.62x39mm Soviet	2,350	1,520 (nasty FMJ round that has some hustle and hits hard)
7) .303 British	2,460	2,418 (fullsize rifle round comparable to U.S. World War II M1 Garand’s 30-06)
8) .450 Marlin	2,225	3,572 (a shoulder-fired artillery piece for rapidly dropping any big North American game)
9) 22-250 Remington	4,150	1,530 (tiny .22-caliber pill hustles so fast it almost turns steel to plasma)

The Good Stuff
It's nice having shooting titles like Guns & Ammo and Petersen's Rifle Shooter magazines in the same building for us to mooch off of. We went up a few floors to visit our buddy Rich Venola, editor of Guns & Ammo and raided his ammo locker of whatever Hornady ammo would fit our weapons. Hornady is just great stuff, delivering high levels of accuracy with match-grade dependability. If you're a shooter, we highly recommend checking the company's product out for yourself.
Contact: Hornady; 800/338-3220, www.hornady.com

The Running OrderTo prerun for this event, we hit the desert and shot the following caliber weapons at varying thicknesses of steel plate to determine how destructive each was from 1-9. For what it's worth, we've included the ballistics data as taken at the muzzle for each round as found on Hornady's Web site (where applicable). Note that sometimes velocity can make up for sheer impact energy when it comes to punching holes or damaging steel plate.