>>64169071
>will not penetrate PE level IIIs
Depends entirely on the model in question and what exact variant of UHMWPE they're using. Unless you can provide definitive test reports proving otherwise, they are at risk of being penetrated by M855. Burden rests on the plate.
Upthread there's a PE plate that literally loses to 9x19mm DM91 - which is tungsten core but extremely slow in comparison. Also inferior geometry.
https://www.youtube.com/watch?v=3l3kvxXP_yM
Other plates, such as the RMA #1003, do in fact get trounced by 5.7 SS190. While that's only a "IIIA+" PE plate, it is rifle rated and only not Level III because of insufficient multi-hit against 7.62x51 M80.
Saying that an ARP will not penetrate any PE Level III is a massive, sweeping overgeneralization. They're a crapshoot against hard-core threats, and are more expensive than their ceramic counterparts.
Example #1: Hesco 3404 is $540, ceramic Hesco 3411 is $370 and rated to M855A1 / BZ API. Prices per plate.
Example #2: RMA #1165 is $250, ceramic. Level IV.
Example #3: Hesco 3800 is $640, ceramic Hesco 3810 is $599.
Example #4: Hesco 4403, while heavy, is $205 a plate on a good day. Level IV.
It's true that PE plates are lighter, but not definitively enough to make them viable general-use plates. The Hesco 3800 is 2.2lb, the Hesco 3810 is 3.9lb and can stop M855A1 on a rough v50 basis - see Buffman test. M855 is no problem, six hits per Hesco's data, none. Between the 3800 and 3810 you're compromising reliable M855 defeat to save 3.4lb. The newer 3811 is $1,355 a set and only 3.4lb a piece, reducing the weight disadvantage to only 2.4lb versus the 3800. There is a 3801 PE plate at 1.95lb, but it's unproven and curiously lacks NIJ certification versus its ceramic and earlier counterparts.
You should also never settle for a v50 against a common threat. "50/50 chance" is still a fail. The enemy won't shoot just once.