What size pellets work best with FX Verminator mk1?

HTech

Member
Aug 23, 2015
35
0
I have a FX Verminator mk1 and I am using JBS heavy pellets which seem to work well but I'm wondering which size head to go of with future orders.
I am currently using 5.55 head.
I am trying to get the most accurate grouping possible.

I am yet to clean my barrel, I have just purchased a kit but not sure how much effect this has on accuracy.