It's been ten years since Red Jacket Firearms first opened its doors and Will celebrates the only way he knows how: with a seemingly impossible build. Will calls his mentor Tony Rumore who invented a Siamese: a double M16, which shares its gas tube system. Will wants to one-up Tony for fun and build a Triamese: 3 M16's joining in a triangular formation, also sharing the gas system. While Will works on the build, his daughter Stephanie plans the ultimate surprise anniversary bash for her dad, inviting some of Red Jacket's biggest clients.

Will and Vince are shooting an AK 47 and a sniper rifle at the range when Will gets an idea: combine the parts of each gun to make the first 1000 yard AK sniper rifle. Meanwhile, to fulfill a childhood dream, world champion archer Chris Bracket wants Will to build him an arrow gun and some arrows that explode. And Will thrills a customer by restoring his mint condition WWII Japanese Arisaka Rifle and getting it to shoot for the first time since the customer has owned it.

Kris gets the idea to do a chromed out, 1919 machine gun with a dragon painted on it. Vince loves the idea and wants to add to it a handlebar trigger system. Will realizes they need experts in chrome and handlebars to pull this one off: the boys from Discovery's American Chopper. And, of course, that means an invite to Baton Rouge for Paul Jr. and team to test the tricked out gun. Meanwhile, world-class speed shooter Jerry Miculek walks into Red Jacket looking to alter a Bulgarian Krink. Will shows off his integrally suppressed AK47 when Jerry challenges Will to a bet: if he can fire this AK in single fire mode faster with his finger than someone pulling the trigger on a fully automatic AK, Will owes Jerry a custom Red Jacket gun free of charge. But can he pull it off?

A customer asks Will to build a quad MG 42 that he can take to a gun show that weekend. Will is hesitant given costs and timing but the customer is persistent and has the money to get the job done. Will can't say no. Meanwhile, a gun collector brings in a 19th century French Palm Pistol. Will, who has a sweet spot for historical firearms, can't help himself and buys the gun... even though it doesn't fire. Will tells Vince to fix the gun so it will fire and triple the gun's value. And a customer walks in with a right-handed AR 15, but he is left-handed shooter. He wants the action of the gun changed to fit his left-handed needs. Of course, Will and his team are just the guys to get all this done.

The Red Jacket crew tackles the nearly impossible - taking a fully automatic Mk 19 Grenade Launcher, and converting it into a silenced, single shot select fire weapon. Meanwhile, Kris tries to make a hunting rifle float for a customer, while Will builds a version of a knife that shoots.

Will and the RJ crew are now building guns for helicopters! Red Jacket is building a complete Mag 58 weapons system with a unique twist -- a swivel arm. Will takes a stock Uzi and makes it competition ready. Then, Stephanie goes on a wild ride.

Will brainstorms combining a shotgun and a taser for the police, but someone in the shop will need to be tased for the demonstration. The Red Jacket team revives a demilitarized WWII-era anti-tank gun to honor a veteran, while Will lays down the law for Kris who needs to back off on the front office flirting.

Will's motto "If you dream it, we can build it" is put to the test when a local scrap yard owner challenges him to build a modernized Gatling shotgun. The Red Jacket team repairs a set of antique dueling pistols, and Will is challenged to a duel.

Things get crazy when Will tackles a WWII-era 57mm cannon. Meanwhile, Vince gives an AR-15 the Red Jacket treatment for Super Bowl champion and New Orleans Saints kicker Garret Hartley. Then, things between Kris and Stephanie take an unexpected turn.

The Red Jacket crew creates a dual mounted M240 Bravo machine gun and Mark19 grenade launcher for the local sheriff's Gulf Patrol Boat. Will restores a WWII German Luger after he's inspired by the gun's great battlefield capture story. And Kris finally steels himself to respond to Will's ultimatum — does he choose Steph or Red Jacket?

Will and the Red Jacket crew restore a 20mm Oerlikon cannon and twin 40mm Bofors anti-aircraft guns aboard the World War II destroyer USS Kidd for an explosive Fourth of July air show. Meanwhile, Steph designs a line of ladies Saiga 545 rifles — with fashionable custom paint jobs — much to Will's chagrin.

Will and the RJ crew are challenged to build a double-barreled, napalm spewing, flamethrower cannon. Meanwhile, against Will's wishes, Steph enlists Kris to help her design Derringer holsters for women. Also, Vince rebuilds a German K98 Mauser rifle that has original capture papers provided by their resident gun historian Glenn Harrison.

Will and the RJ crew restore a WWI Maxim machine gun, mount it to a plane engine and create an interrupter system allowing the gun to fire cleanly between moving propeller blades. Also, Vince and Steph team up to modify a Glock with special charging handles to help a customer with multiple sclerosis safely fire again.

Will and the RJ crew create a muscled up, silenced, night stalking AR to take down the wild hogs that are tearing up Louisiana farm land. Also, Charlie scores big when he finds rare, pinfire ammo for a 150-year-old, $7500, 20-round French revolver.

Will and the Red Jacket crew resurrect an 82mm Russian mortar, and push its limits going HE - high explosive - while testing. Then, tempers flare when Kris has trouble building the new, RJ Desert AR. Also Ted Nugent stops by for some belt fed, full auto madness.

In this explosive season finale, Will, Steph and Kris head to Vegas to demo the Red Jacket Desert AR - an American gun built to challenge the AK during all-conditions desert warfare. Then, everyone is stunned when Red Jacket loses a valued member.