I know this is not specifically about air rifles but it's worth looking at the fighting in the Italian Alps during the First World War between the Austro-Hungarians and the Italians. There was heavy use of pneumatic mortars beginning with their first use by an Austrian infantry division.
The smaller pneumatic mortars would arguably be as good a choice for guerilla actions as air rifles with the specific benefit of adding some firepower with a much reduced risk of detection when firing.
There's an article on The Firearms Blog about the specific region I mentioned above: -
https://www.thefirearmblog.com/blog/...ortars-in-wwi/
The following webpage gives some specific data (weights etc. etc.), for a small pneumatic mortar: -
https://www.awm.gov.au/collection/C158776
And if you really want to delve into the topic, it's not surprising that the following website has a number of pages devoted to air powered mortars including homemade versions/conversions.
The spudfiles
http://www.spudfiles.com/pneumatic-c...opic22487.html
http://www.spudfiles.com/pneumatic-c...opic24092.html
http://www.spudfiles.com/pneumatic-c...opic21662.html