In this context, it seems worth pointing out that

• "blowing from guns" was a punishment for mutiny invented and practiced by the Indian Mughal Empire, not the British

• and that the rationale behind may have been a last show of respect to high-caste offenders. As this quote states:

Mr Montgomery, judicial commissioner of the Punjaub, issued an address to one of the native regiments, two sepoys of which had been blown away from guns for mutinous conduct. He exhorted them to fidelity, threatened them with the consequences of insubordination, and added:

'You have just seen two men of your regiment blown from guns. This is the punishment I will inflict on all traitors and mutineers; and your consciences will tell you what punishment they may expect hereafter.

These men have been blown from guns, and not hanged, because they were Brahmins, and because I wished to save them from the pollution of the hangman's touch; and thus prove to you that the British government does not wish to injure your caste and religion.'

"The history of the Indian revolt, and of the expeditions to Persia, China, and Japan, 1856-7-8"
by George Dowd 1859, available on Google Books

http://books.google.com/books?id=wwYUAAAAQAAJ&pg=PA199wish