Hmm... a Val, DSR, PTRS and PDR.

Can the PTRS round actually punch through modern vehicles?

And a Gyrojet rocket pistol, to boot.

Some modern vehicles, yes, mostly softskins but really anything STANAG 4569 Level 3 or below. 14.5mm-resistant Level 4 is common on modern APCs, though; the Bradley, Stryker, and Puma (all without appliqué armor) are rated to withstand 14.5mm. A modern MBT, though, no; Wikipedia gives 40mm of RHA as the 14.5mm's penetration at 100m. Something like latest M1 or Leopard 2 variants might have over 1000mm of RHA equivalent at its most heavily armored points, and I can't imagine that dropping below 40mm except at the usual tiny World of Tanks-esque weak spots like viewports and such.

Edit: I should add, the widespread adoption of 14.5mm protection was developed more to protect against the KPV machine gun, which is fairly common as armament on former Eastern bloc vehicles, rather than the old PTRD/PTRS AT rifles.