This set is in .25 caliber

Huma-Air Caliber Exchange Set with V2 Dual Hole Transfer Port and High Flow Pin-or-Pellet Probe allows you to change the caliber of your FX Impact with the use of your existing barrel components.

Features:

• The set includes the stainless steel FX Barrel Attachment, V2 Dual Hole Transfer Port, a Liner Lock Nut, a High Flow Pellet/Slug Probe, and the supporting o-rings for the optional FX liner inside the barrel sleeve (the liner itself is not included).
• This kit allows you to use your existing barrelsleeve and shroud and change the liner of your FX Impact with a liner of the same length and a different caliber. 
• The V-shaped transfer port opening makes sure you will have the maximum and smoothest air passage area. The middle support bridge divides the transfer port into a dual hole port and the middle bridge makes sure the pellet or slug nose cannot fall into the enlarged transferport hole, but will be guided smoothly by the middle bridge into the barrel. This set will give the maximum airflow behind the projectile.

Important Notes from Huma Air:

• FX uses a medium strength treadlocker to fixate the transferport to the barrel to prevent the barrel coming loose. Huma advises you to use a treadlocking adhesive like Loctite® 2400.
• Changing from a larger caliber to a smaller caliber does not require any modifications to your shroud or moderator because the bore of the shroud and moderator will be large enough. When you go upwards to a larger caliber, you need to check the bore of the shroud and moderator, and if needed open up the diameter of the bore of the shroud and moderator to match your new caliber.
  • Minimum bore diameter for a fixed shroud would be:

Cal .22 = 6,5 – 7 mm. bore
Cal .25 = 7,5 – 8 mm. bore
Cal. 30 = 8,5 – 9 mm. bore

• With an telescopic shroud, you should use a larger bore as there can be some more movement in the construction so the pellets won’t clip.
  
  • Minimum bore diameter for a telescopic shroud would be:

Cal .22 = 7 mm. bore
Cal .25 = 8 mm. bore
Cal. 30 = 9 mm. bore

• Any modification done to the airflow of your rifle will affect the entire setup and performance. You might need to re-adjust the settings of your rifle again to get the best possible performance.