Hey Shaka -There's some problems with this, but I congratulate your ingenuity. 1 - 155mm arty rounds have driving band designed strictly for breech loading, so no muzzle loading w/o mods. 2 - 155mm round designed for high-pressure arty and has thick walls to take the acceleration w/o breaking up. This limits amount of explosive. Mortars are low-pressure so mortar ammo can have more explosive. 3 - the larger 155mm projectile would need proportionally longer barrels to get the range of a smaller diameter mortar. I'm picturing the crew on ladders... 4 - rate of fire would be a lot lower due to weight of the projectile and #3 above. 5 - The new 155mm howitzers on the horizon can outperform morotars in the arty role, and the current 120mm mortars work damm well. 6 - Doctrine for arty and mortars are different. Mortars are for inf support, while arty is more for combined arms. McDuck

mcduck's points pretty much sum it up. 120 mortars are about the right size for thier role. The differnce between Mortars, Guns and Howitzers are largely trajectories - Mortars: Generally shoots as high as the do far e.g for a target at 600 meters, the round will go at least 600 meters in the arc, guns are a more flat trajectories, ie. a more direct path onto target. howitzers are inbetween. There are pros and cons for each - thus, why they have pieces of all types. I wouldn't discount the 105 yet - some new guns are coming out, e.g the 105 arty variant of the Stryker and the upbarreling available from the UK. Certainly though , the new ultra lightweight 155s (such as the M777) are making the 105s more redundant. Pucka

Agreed, PuckaMan. If you want to shot over a hill, or target someone on the backside slope of the hill, the mortar with its high arc is ideal. But you'll need artillery to get at targets over 10 miles away. If you really want a large mortar, there is the Israeli Makmat (Soltam, and its Finnish Tampella counterpart) 160mm mortar (which can reach over 10km), often Sherman-mounted. And also a Russian-built (and chinese copied) version. Also, the Russians have the massive 240mm, which can be towed, but is also in an SP mount with a loading assist device (for the 130kg shells) called the M-1975/SM-240/2S4. Both the Russian types have a laser shell available (the 240mm Smel'chak round reaching about 10km). And the problem with larger mortars is that without a loading assist device, few crews want to hoist those heavy shells up that high. So often, these beasts are breech loaded. And that effectively allows a larger firing envelope, offering a more direct-fire capability for shorter ranges if so desired (120mm systems used in this direct mode are also having sabot rounds incorporated to enable heavy armor defeating options. 81mm "combination" guns, as they are called, also offer this option.) And with the direct-fire ability, mortars are effective just as much as some howitzers. For very light platforms (small AFVs and trucks) which cannot mount the recoil systems of heavy artillery, mortars are the ideal solution, especially if you have no long-range fire support requirements. And as far as mortar fire offering effective fire support when compared to artillery, the AMOS 120mm system can, in some examples, mount a quad (yes, 4 tubes) installation that can effectively be fired from 20-tonnish hulls, such as the CV90 series. These could effectively fire a 4-12 round "time on target" volley, then scoot off. And as we mentioned that lower-velocity mortar shells are thinner-walled and carry more explosive per shell than standard artillery rounds, such a volley of 120mm rounds (which can be "clip fed" by some of the autoloaders available to the turreted mortars) could put out the same destruction as a small battery of artillery guns out to medium ranges (current 120mm mortars can cross 12km.) With the capabilities of current mortar ammunitions, including PGMs and cluster/carrier rounds, mortars are not going away anytime soon..

And you forget French 120 mm riffled mortar: accurate, 600kg light, firepower of a 155 mm howitzer agaisnt infantery, and more than 10 km range. 155 mm mortar are useless. i would also mention that aerodynamic of a gun shell and mortar shell is totally different. In fact you need 155 mm caliber for range and destructive power on trenches and concrete wall with greater penetration.For killing infantery mortar is ideal especially with submunitions shells.

I believe 120mm is about the max practicle size for a mortar, anything bigger howitzers are more practile in most respects. I think the 105mm still has its place particular in the Marine Corps and light Infantry forces. The 105mm, due to size, has a smaller footprint in terms of deck space, prime mover and logistics support. If memory serves given the same amount of helicopter lifts I can lift a battery of 105s plus at least 100 extra rounds more ammo than a battery of 155s. They may have lightened the 155 but they have not reduced its dimensions or ammo weight. If you look at places like Afghanistan where almost everything is moved by Helicopter and the altitude taxes the Helicopters performance the logistics of the 105 has a definite advantage. Just as important is that you can drop the 105mm a lot closer to Friendly troops should the bad guys get in the wire.

THE EXACT OPPOSITE is about to happen! We are looking at smaller guns to reduces the logistic footprint! With Smart Shells, it does not take as large of a shell to destroy most targets! In the future, I envision, a squard direct fire launcher, backed by a company 81MM mortar, then a battalion 105 gun/howitzer and then by a 160MM rocket launcher. Covers the entire range of targets with the minimum of fuss.

An artillery shell is spin-stabilized by the rifling in the barrel of the gun. It’s sides are parallel and has a driving band that fits into the rifling and causes it to rotate. A rotating shell is ballistically stable in flight, and tends to point the nose in the direction it’s going. This means the nose will be pointing down when it lands. Artillery shells are typically mush hearier than mortarshell of the same diameter because they are not tapered. A mortar shell is fin-stabilized. If it is an un-rifled mortar, the shell does not turn in flight. Many modern mortars are rifled. A mortar shell is tapered in back and fins are mounted on the tail to make it fly straight. The fins also make the nose point down when it lands. This means you can't use artillery shells in mortars. While simplifying the logistical tail would be a good thing, you can't do it this way. The physics get in the way.

Damn physics! With the current crop of guided 120mm Mortar rounds comming online, developing a 155mm mortar system would be a huge waste of resources. It could be done, and the larger size would allow more specialized rounds, like the 155 arty, but part of the appeal of mortars is the simplfied logistics tail, allowing it to opperate forward with the units it supports. Guided rounds and possibly submunitions are as fancy as you are goint to want to get anytime soon

One more comment, I have seen 155mm and larger mortars suggested with limited range (i.e. shorter barrels) for company and battalion support. This goes with the big bang theory, but I agree that improved munitions in existing systems is a far better use of resources.

Modern 105 shells are as 'effective' as slightly older 155s. the 105 is also lighter and the munitions easier to move about.