73 Cal Monster Rifle, Recoil Videos

I have been filming recoil from my custom 73 cal (12 bore) "rifle" which is a converted bolt-action 12ga shotgun. Cases are custom RMC for chamber. Feed port has been opened and mounts re-drilled--not that I would want a scope on it. Heavy bbl. Ejector modded for long cases to eject. Load is using a 1040gr cast, hardened and lubed bullet, between speeds of low-end 1300-1400FPS (light loads) and high-end 1850FPS full case loads....which is all the recoil I can take. The 1850FPS load is roughly 260ft-lbs of rifle recoil energy and 45FPS gun velocity into my shoulder (8.1lb rifle with standard butt cushion); well above .577 T-Rex recoil. As you can see you just have to hold the gun and not jump in the air when you fire the gun.

The 1400FPS load is near 160ft/lbs of free recoil but it's accurate enough to stop a charging <anything on Earth>. The recoil moves the rear sight up the ramp each shot a little bit, and it's as tight as I can make the screw. Finally the recoil busted the green fiber optic out of the rear sight. Whoops.

Here are a couple shots I fired on the high-speed camera (it's a cheaper Nikon V1, not professional "high-speed" camera but works alright): http://www.youtube.com/watch?v=bVy3GEotwBA

One video clip in here shows a typical 338 Lapua I recorded a guy shooting on my range for comparison: http://www.youtube.com/watch?v=X53MJOtpC80&feature=youtu.be

The gun:

Pressures were tested in a "pressure gun" between 12,000-20,000psi. Not a round for a regular 12GA bbl, it would blow the bbl up.

There's no penetration testing that I have found I need to really do. It is like a freight train hitting snow. Seems to just plow further the faster it goes. I know exactly what you are talking about down at .458, but that applies more to higher speed capable projectiles that weigh less, where more energy is exerted on a smaller amount of total metal, and so the bullet is more finicky about what it impacts at speed, before its metal starts yielding. This yielding tends to simply increase with speed until the bullet highly fragments--but the total energy released on impact is still there in some way. It's really apples and oranges here because of bullet scale. Also, if it were pushed to faster speeds, my shoulder would start to dislocate on each shot.

The 1040gr bullet lives up to rocks in its path with minimal deflection or weight loss. I have seen that bullet make some very long trenches in or through rocky-clay type dirt that was dry. It simply does not want to deflect. IF you can find the bullet, it is usually still straight in the path, and looks as if it could be shot again basically. Meplat is still flat.

A steel plate stopped one bullet after it went through two of those stumps stacked end-to-end just like the single one in the video, it left a large dent on 1/4" steel through to the back side--not much of a hole carved out like a smaller caliber would do, but the bullet only weighed about 600 grains from the nose eroding, as hardened-lead pushed flat up against steel. That was the only one I saw or found that lost semi-significant weight. I still have that bullet. I still have one shot through rocky clay also that popped right out of the back of the dirt mound and literally bounced out about 5 feet to a stop. Was laying on top the ground on the other side. Daylight could be seen all the way through the hole in the mound.

I have some knowledge the cast maker of the bullet has passed to me when the bullet was first tested. It was tested at a big-bore convention. Same 1040gr bullet, but lower velocities.

Here's what I was told:

The truncated-cone 1040gr cast bullets were tested at a Linebaugh big-bore seminar. First test consisted of a stack of wet paper, and then [wet paper>cow femur>wet paper] on the second test. Both tests shot at a 15 foot distance. Bullets were fired at a slow 1,080fps.

Penetration through paper-only with the 1040gr slugs was 48" on average. I was told that the 416 Rigby was only getting around 26". (This is the "apples oranges" thing I am talking about vs .458 cal or smaller bullets.)

On the second test, it was going through 4" of paper, smashing cow femur, then penetrating another 36" of paper. Bullets weighed over 1,000grs after being recovered.

Buy a different rear sight brand. I used those cheap Hi-Viz sights just so I could get a little more depth of field from the bright dots they have. They do work I'll give them that, for visibility. Or did work. I might be able to get a new sight to lock on better with a little hand finishing work to the underside to better its fit on the rail. It's just nuts in a way that it's as tight as it goes, and that little tiny bit of metal has enough inertia to walk up a ramp it's clamped to.

I think a scope on this gun would probably throw an objective lens out of the front and kink the tube at the same time.