They make great lead flux
I have noticed that some types of plastics become brittle when subject to a couple freeze/thaw cycles. I first noticed this with a couple food safe plastic buckets.. Could that be what happened to these old wads?
A trick that works with nylon zip ties is to boil them in water, I suspect wads are polyethylene so it probably won't work but you've nothing to lose.
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |