Kybuckhunter,
Are you pushing the cap down onto the nipple or just sliding it on? Most times a gentle push will suffice as the nipple is tapered so the cap will spread to fit. You shouldn't need to squeeze the cap, that's not a good practice to get into. I've used CCI, Remington, and Winchester caps on my rifles and never had an issue with any of them. It's possible (but unlikely) that you have a #10 nipple or one that's defective. I bought a brand new #11 nipple once that the caps would literally fall off from if you were to tip the rifle upside down. I'd buy a new nipple (I like Uncle Mikes) but the TOW nipples should be fine, just make sure you get the correct thread for your rifle.
BPS