What were the effects of the invention of new kinds of rifles, bullets, shell, and canisters during the Civil War?
The effects during the war have been outlined well, one of the effects that has been widespread and less documented (though a recent article the in the Journal of Foreign Affairs gets at it quite nicely "Small Arms Big Problems") has been the proliferation of the types of reliable small arms that actually start with things like the British Enfield Rifles (developed similarly to the new repeating rifles of the Civil War). These new types of reliable and accurate small arms have led to a change in the way insurgencies and other regional conflicts work.
Yes these inventions added to the bloody and tragic nature of this war, but was there not an economic boon as well. Doesn't someone always profit from the war? Another result of the use of new weaponry and accessories (not quite sure it's the right word.) was the economic boon provided for those who fabricated these things.
I think military innovations such as those listed above, or any military innovation is going to, by its very definition, be more bloody because they allow more enemies to be killed more efficiently and easily than before. This can be clearly seen in the Civil War. Likewise, as #4 points out, those who possess the technology clearly have an advantage which is likely to win them the battle, making military innovations eagerly sought after.
Most of the technological advancement came on the Union side during the war, as repeating rifles, breech loaders, and more accurate and explosive artillery was developed. The South had very little in the way of resources or industry to make such advances.
Confederates facing William Tecumseh Sherman's army in Georgia in 1864, newly armed with repeating rifles, complained that Yankee soldiers could "load up on Sunday and keep shooting all week". So one of the major effects was that it shortened the war and hastened a Union victory.
The Civil War was the deadliest war in American history, primarily because of new weapons, primarily the rifled barrel. Previous guns were smooth bore, and accuracy was problematic at best. Bullets and rifle balls were not evenly weighted, and would not travel in a straight trajectory. It was this lack of accuracy that had led to charges, etc. With the introduction of the rifled barrel, the bullet or ball would spin, and thus counterbalance itself. As a result, guns were much more accurate, and one firing at a target could reasonable expect to hit it 100% of the time, barring wind, etc. In addition, Southern soldiers were primarily farmers and country dwellers who had much more experience with weapons than did their Northern counterparts. This new method of weapon led to indescribable carnage.
The main effect of the invention of these types of weapons was that they gave the defensive side major advantages in this war. This was one thing that made this war so horribly bloody.
Before the invention of such efficient weapons, the offense tended to have the advantage in war. By pushing with its infantry and cavalry, the offensive side could often break the other side's line. But now, with these inventions, a defensive army (especially if it were in prepared trenches and other defensive positions) could lay down such a volume of fire that charges would be almost suicidal.
This was seen at many points in the war. Many soldiers died simply because their commanders thought that headlong charges were the way to win when, in fact, the new inventions made such charges deadly.