Yep i got to googling Long Tom and a little stumble turned this up.
https://www.hastingsdistribution.com/index.php?l=product_list&c=50
https://www.metrogun.com/how_it_works.html
https://www.metrogun.com/
https://www.hastingsdistribution.com/index.php?l=product_list&c=50
https://www.metrogun.com/how_it_works.html
https://www.metrogun.com/