yes they are, and yes it does... 
“...5 inch long bullet...”
I have in front of me a 50 caliber machine gun cartridge. It measures 5 1/2 inches. Are they talking about a rifle made to shoot a 50 caliber machine gun cartridge? That would have one hell of a kick to it!
I have fired 50 cal machine guns, and thank God they were anchored down. Recoil from my 12 ga pistol grip shooting 00 or slugs is a lot for me to handle. I can’t imagine shooting a 50 cal, 5 inch cartridge from a rifle.
And yes, Dorner is some what bigger, and a lot younger than me...still...
yes they are, and yes it does... 