Why not to simply take some guns from the Shadow Earth and kill Eric?

Question

I’ve just read the first book from The Chronicles of Amber. I’m wondering, why didn’t Corwin or his brother Random take a machine gun, or just a gun, maybe some grenades, maybe some other weapons like a bazooka, then go to the Pattern which is located in the underwater city (they could carry their guns in waterproof boxes), and then appear in Amber and execute Eric?

Or let’s say, why didn’t they take some vehicles from shadow Earth, like a small army of tanks and maybe planes and jets?

Instead of this, they took from Shadow Earth just two pistols and a very little amount of ammunition, which soon they run out of. And Corwin had to fight with Eric using his blade. If he had had a gun, he could have simply killed him.

And then Eric and his other brother gathered an army around 250,000 savages to storm Amber. So a couple of jets and tanks would have been much better than this.

Answer 1

The short answer is, Read And Find Out - you're only on the first book of a 10 book series.

The longer answer...

Yuuuge spoiler:

Gunpowder doesn't work in Amber.

However, in the 2nd book in the series, as summarized by Wikipedia:

All of Corwin's siblings believe that guns cannot function in Amber, as gunpowder is inert there. But Corwin has secret knowledge: in the shadow world of Avalon, where he once ruled, there exists a jeweler's rouge that will function in Amber as gunpowder should.

The rest of the book describes an attack such as you suggest... no other technology, though; I believe Internal Combustion Engines are also said or implied not to work near Amber.

For the remainder of the first story arc (books 1-5), Corwin's discovery is not dealt with, as other issues take precedence. By the time of the second arc - 20 years later, say - it's considered a quaint history of something that happened once and not active technology, until

Luke Raynard organizes an army of mercenaries armed with the substitute gunpowder, and Dalt later leads the army to threaten Amber. The Amberites pull the guns from Corwin's period out of storage, dust them off, and confront Dalt.

The lesson that Merlin gleans during Sign of Chaos, which you might appreciate, is that Benedict has been studying war across all time and Shadow. Guns are not magic, and if both sides have them, then Amber is still very well protected.