I originally thought “blunderbuss” loaded with either number 1 buckshot or maybe even butter knives or forks but thought the Mac-11 would be more controllable… same amount of ammo but in controlled bursts.
Easy question. M-14.
Give him an AA-12 Automatic shotgun with Dragon’s Breath shells, ask the king for some watermelons (or whatever large vegetable is available). Demonstration should be suitably messy.
Out of the firearms I actually own? My AR-15 with one mag of “Green tip” armor-piercing cartridges, one mag of hollow point defensive ammo
Set the target up at 200 yards, a pig carcass in traditional plate mail armor, and traditional helmet with visor opening, and a pig carcass, unarmored
First shot; through the armor, showcasing the AP ammo
Second shot; through the visor opening, showing accuracy
Third shot; body shot on unarmored pig with the hollow point rounds, showing damage to unprotected soft tissue
Fourth shot; head shot on unarmored pig, showing the effectiveness of headshots with HP ammo
I’d use an old Winchester rifle, like Chuck Connor in The Rifleman. Most other armaments are missing the cool swagger potential of his particular rifle. It could snipe, it could be twirled one-handed, it could rapid-fire, it could shoot from the hip, it could be quick-drawn. This would be primitive screwhead wizardry of the highest order.
I’d go with the pump action shotgun in 12ga, and bring some 000-buck and 50-cal sabots for ammo. Plenty of range, easy to use, reliable, louder than it needs to be and you can cut a sapling down before you start perforating armor for demonstration.
If it gets to the point of actually using it on a knight on a horse, ugh. Nasty.
I would drive my truck to Dave’s, load up every gun and round of ammo he had.
Sorry, Dave. You’re on your own.
That’s why I picked the Garand. I’d rather kill the smelly bastard while he’s at the other end of the field, not when he’s gotten up a head of steam and is charging at me on a bloody huge horse.
You’re aiming too low.
How accurate is an RPG?
Dave, you said that you would let me be there when you used that machine! C’mon now, its only fair since we built it together. We agreed on this. You did win the rock-paper-scissors game, so you go first, but I am supposed to be there with you.
Well heck, since it is a time machine, I can come back to you when I have decided on this choice. See you in a minute (your time) this will probably be a few days in my time. Right now I need some sleep. You know better than to call me in my night time, I work 3rd shift as you are well aware.
See you soon Dave, 48.
The above is pure BS of course, but I just could not stop myself. G’nite all.
As for the RPG: I’ve never fired one, so not accurate at all. Single-shot, too.
The RPG, though, would have the effect of the knight running away and cowering in the bushes. Not a chance anyone wants to face you with that thing after seeing it explode a house.
That said, I think the M-16 with M-203 is the best bet. If not that, then perhaps a SAW (M249) with a 200 round drum with tracer rounds (tracers would have the effect of making them look magical too). A SAW can be handled pretty easily by one person too (why I didn’t choose the M240). Throw 100 rounds downrange at a group of knight standings with armor and watch them get riddled with holes in a matter of seconds, and they’d take notice.
Now, if you were trying to impress them for a battlefield weapon to be used by more than one person, I’d get a MK-19 grenade launcher and take out a few buildings half a mile away. 
Not so good for close combat, though.
Thanks for the answers everyone! Interesting choices but I think I’d go with this one myself:
Of course I’m taking a chance that I’ll be able to figure out how to use the grenade launcher…
HK battle rifle in .308, dependable accurate, powerful.
Would drop a big ass charging horse if need be.
There’s one button to open the breach and then there’s the trigger.
M32 – it’s like an M203 not mounted on the M-16A2, but with a 6-shot rotating drum – and I’ll bring a dozen extra for a total of 18 shots.
And I’m a soft-hearted guy, so I’m gonna let the knight live (and ruminate, and cower) with a slightly different demonstration:
Knight & Squire and I face two groups of “opponents” which are in two groups at the other end of the field.
Knight gets to use his horse and his lance, The distance between the Squire and the Knight’s ‘assailants’ is whatever the knight finds optimal for his grab-aim-set-and-skewer routine. Knight’s group is two suits of armor in a single-file line heading toward the night and, since the knight’s targets are lined up so conveniently, it’s a piece of cake for him to skewer both of those tin cans in one charge.
I will stand a few feet to the right (or left, doesn’t matter) of the Squire; far enough away that I won’t be interfering with Knight or horse or squire during their hand-off. My group is three suits of armor set a few feet to the right or left of knight’s group, so that we’re attacking at the same range. However, my group is approaching me side-by-side, which is harder to skewer in one attack.
My bet: I can take out my assailants before Knight can defeat his assailants. The competition begins when knight’s horse crosses the line where squire and I are standing. Furthermore, the squire will dutifully hold knight’s lance up in its regular position for the knight to grab and ready it as he rides past – same stuff they’ve done a million times at jousts and so on – while my M32 will just lie there on the ground at my feet.
Knight can start from wherever he wants (presumably a few yards behind the line of squire & me). King gets to count down to GO! It doesn’t matter to me since I’m not actually moving until well after the horse is already in motion.
As soon as the knight grabs his lance, I can drop to one knee, grab the M32, aim, and send a grenade to my assailants. If my aim is short or long, I still have time to send another grenade down range after adjusting. If my grenade lands within a yard of one of my assailants, the explosion alone will probably knock the empty suits over. If I’m really lucky with the first shot, or if I still have time and feel it’s safe, I’ll even take out knight’s assailants well before he’s close enough for the flying shrapnel to injure the horse.
I can just imagine the knight pulling his horse short of his assailants with a :eek:
look on his face, then turning to see me pointing the M32 at him and his steed, with two more grenades in the rotating drum.
–G!
M1A1 Abrams
let’s joust.
Download a manual from the internet and try it out on the vehicle of someone you don’t like, then jump in the time machine… What, car, I was no where in the area at that time last night, I was, um, in um…
M4, Eotech sight, Pmags. Or a phased plasma rifle in the 40 watt range.
Okay that made me lol a little.
Are we staying permanently in King Arthur’s court or taking a day-trip. If it’s anything other than a day trip, I have to go with a muzzle loader I think.
If it’s a day trip, then a Winchester Model 94 (30-30 round). Or a flamethrower. The whole fire thing IS gonna impress them. They can’t see the bullet at speed, but they can damn sure see a 65ft tongue of flame, and Mr. Knights horse is NOT going to charge into a fire.
Regards,
-Bouncer-