The people at Pro Sound Effects are giving away a sample library of 290 sound effects. Not all of the sounds are useful, but there are some good ones (gun shots etc.) especially if you are trying to start building your sound library.
BTW. I am in no way affiliated with them and don’t get anything from this. I just found it useful for myself and decided to share with you.
Here is the link: https://www.prosoundeffects.com/free-sound-effects-download
I hope this was useful to you.
Cheers!