I am intersted in running a First World War scenario, and I decided to try this product in the hope that it would have statistics for the weapons of the First World War.
This supplement has detailed information on weapons and new firearms rules. The rules made some good points about Call of Cthulhu. How do you make an aimed shot in Call of Cthulhu? The rulebook doesn't talk about it, but this is important because so many players arm themselves with guns. This book suggests some rules that appear workable.
The weapon descriptions are very thorough. I have no complaints about the descriptions.
Overall, this product is very good. It didn't have every weapon I was looking for, but this is Volume 1, so I expect other volumes to come along and add more information.