I'm looking for datasets that contain violent crime stats involving guns. I've googled but have only found organised and graphed data and I would prefer raw data that I can aggregate.
This link is the Bureau of Justice Statistics start page on fire-arm related crimes:
These blog posts by master Windows programmer Charles Petzold contain a few tables by country, and list a few other sources, notably the FBI.
The analyses are brilliant - they look effortless and to-the-point.
Assumption: you are interested in United States data. This is all I really know about, sorry.
Unfortunately, I don't think you are going to find raw/disaggregated data at a national level. You probably already know about the aggregated FBI UCR datasets.
I think what you are looking for is what the public safety ecosystem calls "Incident" from a system such as an RMS ("Records Management System"). See http://publicsafetydataportal.org/records-management-systems-data/ for more details.
The good news: due to many reasons I won't go into here, many cities are publishing crime data online. The bad news: they are almost always in a different format/schema. You can find several examples in varying formats and (from zip files to CSVs) at the publicsafetydataportal.org link above.
You can also run a search for "crime" and other keywords on http://opendatanetwork.com
* if you want a very high probability of being able to export the data as machine readable (CSV, XML, RDF, JSON) as well as filter using the web UI / standardized API
* = Disclaimer: I work for Socrata, the company that created and maintains opendatanetwork.com. We have also done some work with the Police Foundation which runs publicsafetydataportal.org where datasets are sometimes but not always powered by Socrata