.177
The Verminator Extreme .177 has a M20x1 threaded barrel shroud. I recommend the Sumo .177/.22 M20x1 #S7.
https://donnyfl.com/collections/ldc/products/1-5-x-6-5-inch-sumo?variant=13719820828715

.22
The Verminator Extreme has a M20x1 threaded barrel shroud. I recommend the Sumo .22/.25 #S61. Please add a note stating you need it with the M20x1 rear cap.
https://donnyfl.com/collections/ldc/products/1-5-x-6-5-inch-sumo?variant=33070855487531

.25
The Verminator Extreme has a M20x1 threaded barrel shroud. I recommend the Sumo .25/.30 M20x1 #S10.
https://donnyfl.com/collections/ldc/products/1-5-x-6-5-inch-sumo?variant=13281748516907