.45 acp went through 15 layers of 1050 denier ballistic nylon at 3 feet. under the same conditions it can penetrate just under 30 layers of dry fiberglass, but not 1/8 inch doron fiber glass.
the one of the .22lr rounds penetrated 20 layers
here i replicated the m12 vest of korea, with 1/8 aluminum and 8 layers of nylon. it stopped the .45 right after it penetrated the aluminum.
12 gauge 00 buck penetrated 15 layers at 25 yards.
12 gauge steel with a nylon backing stopped a 7.62 tokarev, that is the equivalant of newer 3a body armor.
1/2" aluminum with a 12 gauge steel backing stopped an ak round at very close range. in a past expariment it was stopped by 1/4" al over 1/4" steel
m2 ball penetrated the 1" aluminum and 10 layers of nylon
7.62x39 penetrated 1/2 inch aluminum and 30 layers of nylon
this late 90's aluminum oxide sapi plate stopped m2 ball but not M2 AP. i shot the AP first.