This is just for fun, having a bit of fun with a couple gun writers:
comments:

As Mr. Jurras has previously suggested, the 105 mm cannon used by our army has certain problems as a carry weapon. I will try and explain some of those problems using our usual tools.

First weight. Overall, I would guess the gun, with breach, etc. weighs in around a ton, or 2000 pounds. Rather a difficult weapon to carry, regardless of shoulder harness design. But, it does have benefits, if you can get it there.

A South African firm is currently develop a low recoil, break down version of this gun,that can be carried in a back pack, then reassembled. The project is not looking really good, at this point.

With a range of 27 miles firing a 37 pound shell, at 2900 fps, or a 30 pound projectile at 3700 fps, it provides a versatile approach to taking game.

I based the following calculations on a
259000 grain bullet at 2900 fps, and a 203,000
grain shell at 3700 fps.

One of the classic means of calculating the hitting power of your round is the Taylor K.O.
formula. Rather then bore you with the details,
these two rounds come out at a dead heat, with
a Taylor rating of 429,200. Sufficient for the largest game in North America, but perhaps, a little weak for Somalia, or similar terrorist harboring countries.

Ft-lbs of energy have always been used, and usually favor velocity over bullet diameter.
With a bullet caliber of about 4.00, expanding softpoint bullets aren't really necessary. We do however, feature high explosives, and, these more than make up for the lack of an expanding hollowpoint in this caliber. However, it's hard to zero the gun, since everything in the view finder disappears upon impact.

The heavier round, the 259,000 grain bullet, yields a light 4,837,842 ft lbs of energy.

The lighter, faster moving projectile, designed to defeat armor, has a nice magnum punch, at
6,172,419 ft lbs of energy.
Needless to say, continued use of magnum loads,
pressure, and powder eventually diminish accuracy, and barrel life.
It would be fun to determine energy loss, at 10 and 20 miles, and, if the bullet wobbles, if it ever goes subsonic. However, the computer on the gun takes these events into the siting calculations, and, much like an asteroid, something that large, in motion, retains large amounts of energy, for most of it's length of travel. Besides, it blows up at the end;-)

Most important to real big game hunters is the Wound channel calculation.

The slower, heavier, projectile, at 37 pounds, will cut a 29" wound channel.
The lighter, faster projectile does more tissue damage, cutting a wider, 37" wound channel.

This should be sufficient for all but the largest Afganis.

Finally, Mr. Jurras pointed out the gun maybe a bit much in recoil for the average shooter.

Since powder charges are classified, we can only guess at the powder charge used. By the old method of, the bullet weighs 37 pounds, and the case weighs so much, and loading the damn thing, it weighs about 80 pounds, we figure the powder charge to be somewhere in the half the bullet weight category. It's a very slow powder, since
about 25 foot barrels give you lots of time for the powder to burn. Cordite comes to mind...
So, figuring about 130000 grains of very slow powder, we come up with the following recoil figures.

The shooter receives, with the 37 pound round, a 315,891 ft=lbs of energy, at a nice clip of 101 fps.

The lighter, 30 pound round, snaps the shoulder with a brisk 402,011 ft lbs of energy, at a quicker, 114 fps.

Not for the light hearted, shoulder shooters of either of these rounds are much like motorcycle riders, either alive, never having shot, or, dead after the first shot.

Experience is not something one acquires when using these weapons in an off hand position.

The good news is this weapon has excellent safety features, and, can be carried with a round in the chamber. Off hand snap shots are difficult, but can be mastered with practice.
One of the best features of snap shots with the 105 is the effective accuracy of the weapon.
While other lesser rounds must be precisely placed, to quickly kill your prey, the 4.00 caliber is much more forgiving. Hit anywhere near your target, and the 37 pounds of high explosives, and shrapnel from the exploding case,
give you an excellent chance of dispatching your
target with the first shot.

This is very important, since, as a snapshot weapon, it is very difficult to reload quickly, giving that nasty elephant, train, or truck a very good chance of running you over while you try and eject, and reload. Much like it's smaller brothers, the 4, and 8 bore rifles, one
prefers an initial hit, rather then a second shot.

Now, if Mr. Jurras would be kind enough to compare this to the 50 bmg, we would have an interesting comparison;-)

Keep in mind I'm hedging my bet. I get the benefit of both a tank, a BMG, and a M-60 .30 caliber machine gun, all in the same hunting package.

The usual hunting method is by drop from a C-130,
and, we prefer entry to be made supported by a C-137, better known as, "Puff, the magic Dragon".
40 MM, 6000 rounds a minute.

s
PS
I hope everyone has as much fun reading this, as I did writing it.

Socrates __

Very interesting. My only concern would be to find a suitable commercial indoor range (and then an outdoor range) for developing the preliminary and field ballistics tables. At my last visit to the BRL at Aberdeen Proving Ground, I was still under the impression that ordinary shooters and handloaders were not allowed to use the equipment and premises.

Perhaps with a little coercion, we could convince the President that, as a group effort, the work going on in Afghanistan could benefit from our research; in the field, of course. Federal Grant funding, naturally.

Good shooting.

Robert

I'm old. Used to go with the national guard to Hunter Liget, and use the range.

Guys got sick of shooting, and we had to shoot so many rounds, until everything was gone.

No more satisfying feeling then lining up the cross hairs on the 105, pulling the trigger, and watching whatever you aimed at disappear.

I skipped one round through a tank broad side, and watched it bounce 3 or 4 miles in the twilight. Used a tracer sabot for that shot.
I guess I should put an entry in the longest shots made on the other page;-)

The M-60, and the 50 BMG are awesome at night. You walk the bullets out till you hit your target, watching the tracers.
s

I knew Hunter-Liggett only too well. Horrible place in August, glad to see it closed!

Whether or not Mr Jurras likes the 105, it's a "destructive device" per ATF regs. Fun to dream about, perhaps, but only dreams.

Tracers look cool going out but they make great aiming points for the other side. Units that remove their tracer rounds are more effective against the enemy and reduce their own casualties.

Definitely a Class X, though.

Sarge

This wasn't a dream. It was about 105, degrees, and mm, and everyone was bitchy.

God, I did love being able to shoot those guns, and cannons. Hotter then hell, but it was shoot all day, and keep shooting till all the ammo was gone. That was in the early 80's.
MY sarge-major got me in on a shoot out, and I got to play with all the big toys.

No 120mm cannon at that time, but damn, it was fun. And, we did shoot squirrels, only thing besides rats, I think I've shot.

A 105 is, without a doubt, a destructive weapon. It also moves a tank back, which is what we were, armored.

Now that would be my idea of a safari ride.
A nice little tank, with a 308, M-60, a BMG, and for the poachers, the 105MM,(VEG).

gs

Sarge: you ought to stop by the sixgunner.com website. It's like a damn legends convention for gun writers. Jurras, Taylor, Paco, Taffin, need I say more?
gs

There was a cannon developed in the 50's I believe that fired a atom bomb! You might want to look into that one! 4.500.000,00 ft lbs of energy is nothing to a 300mega ton nuclear blast...

Buell __

The "Atomic Cannon" was 260 mm; trailer or rail car mounted. I was at Aberdeen Proving Ground during some of the testing.

For the others on this thread, we might consider reviving the "Dart" round (spin stabilized) or the "Arrow" round (fin stabilized). Both were chunks of tungsten carbide about an inch and a half in diameter by 36 inches long, fired in sabots from a 90 mm gun tube either rifled (for spin) or smooth bore (for fin). The object was long range armor-piercing. The initial field firings were to the 2500 yard butts. The prototype ballistics tables showed an elevation of about two degrees for that range. The top Sarge in-command said that couldn't right and ordered the elevation up to around 10 degrees; normal for the 90 mm. The first round fired was found 22 miles away in a pig pen just outside of Baltimore. "Sails like an arrow"? You bet.

Good shooting. Good stories.

Robert

bobshawn:
Never heard of that round. Sounds great.

Wonder if we could do that in a Sabot shotgun version???

gs