It not fool proof, the closer the archer, the stronger the bow, the sharper the arrow head, and of course the heavier or lighter weight of the silk garment...

just as "bullet proof" vest worn by the police are not 100% bullet proof, so too, silk was not perfect.. but experments with modern arrow, (steel tipped) shot at manikins, a heavy weight silk serge was intack, more than 50% of the time. it was referenced in Natural History, but the article is not available on line (NH only prints select articles..not the whole zine.)