Purdey's improvement of the Jones underlever was to fit it with a sliding "Purdey bolt" that engaged the rear of the rear lump. This bolt was forced into its bite by a very strong V spring mounted on the rear of the action bar which made the entire bolting system a "snap action". It was so strong that you had to make sure your fingers were out of the way when you closed the action and tripped the bolts so that you didn't get a good bruise. It was used on both hammer and hammerless rifles and maybe a few guns built for heavy loads. I have a 10 bore hammer rifle with this action which I have tried to make a strong enough spring for with little success so far. I left it with "Doc" Hutton this winter for a good one. Maybe this summer.
