Is it appropriate to train in using guns for self-defense?

Islam encourages us to have proficiency with weapons of war. The Holy Prophet ^sas said:

Prepare to meet them (the enemy) with as much strength as you can afford. Verily! Strength is in archery, strength is in archery, strength is in archery.

(Sahih Muslim, Book 33, Hadith 241)

This emergency preparedness is not just for times of war, but for times of peace as well. The Holy Prophet ^sas said:

Lands shall be laid open to you, and Allah will suffice you (against your enemies), but none of you should neglect practicing his skill in archery.

(Sahih Muslim, Book 33, Hadith 242)

This command is not only for men, women should also have familiarity with such weapons. Hadrat Musleh Mau‘ud ^ra explained:

It is mentioned in ahadith that it was the way of the Holy Prophet ^sas to always hold friendly competitions between his Companions during times of peace, wherein archery and other tactics of war and strength were exhibited. Once he held such games in the Masjid, and he ^sas said to Hadrat ‘Aishah ^ra that if you want to watch then stand behind me and watch from over my shoulders. Hadrat ‘Aishah ^ra stood behind him ^sas and watched all of the feats of battle (Sahih al-Bukhari Kitabul- Eidain). It is established from this that Islam considers it necessary to keep women familiar with the tactics of war so that when the time comes she can protect herself and her country. If her heart trembles at the flash of a sword or if hearing the sound of a gun or cannon makes her blood go dry, then she cannot happily give her children permission to go into the battlefield, nor can she bravely take part in the defense of her country. But Hadrat ‘Aishah ^ra, upon seeing any scene of the battlefield, could never say that my heart is constricted, because the Holy Prophet ^sas showed her the tactics of war and he would always keep one of his wives with him during war so that courage and bravery would develop in them as well.

(Tafsir-e-Kabir, vol. 6, p. 303-304)