Benjamin kratos leaking air from barrel

You need a new exhaust valve. Why?
The valve spring is not ground flat at the ends creating the exhaust valve to push to one side a lot. This wears out the face of the soft material used on the exhaust valve.
The gun is under warranty and because it’s imported we don’t make the part. The parts are for warranty use only.
But with that being said I do make upgraded exhaust valves for it and I also think Troy Hammer has them too. If you can’t do the work then I’d suggest to send it back to warranty.
 
USPS policy on air guns


"f. Air guns that do not fall within the definition of firearm under 12.1.1a are mailable. A shipment containing an air gun with a muzzle velocity of 400 or more feet per second (fps) must include an Adult Signature service under 503.8.0. Mailers must additionally comply with all applicable state and local regulations."


12.1.1 Definitions

The terms used in this standard are defined as follows:

[Delete current items 12.1.1a and 12.1.1g in their entirety and replace with the following.]

a. Firearm means any device, including a starter gun, which will, or is designed to, or may readily be converted to, expel a projectile by the action of an explosive; the frame or receiver of any such weapon; any firearm muffler or firearm silencer; or any destructive device; but the term shall not include an antique firearm.

Link to full policy:

 
USPS will ship for your, for insurance peronally if asked I would say "benjamin kratos" but airguns (tho NOT pistols) certainly may be mailed freely.
John

I routinely mail air pistols with no issues. I identify exactly what it is, and the local postmaster is very knowledgeable.


12.1.2 Handguns

[Revise 12.1.2 as follows:]

Handguns and other firearms capable of being concealed on the person are nonmailable unless mailed between the parties listed in 12.1.3 and 12.1.5 after the filing of an affidavit or statement required by 12.1.4 and 12.1.6, and are subject to the following:

a. Firearms meeting the definition of a handgun under 12.1.1b, and the definition of curios or relics under 27 CFR 478.11 may be mailed between curio and relic collectors only when those firearms also meet the definition of an antique firearm under 12.1.1g.

b. Firearms meeting the definition of a handgun under 12.1.1b that are certified by the curator of a municipal, state, or federal museum that exhibits firearms to be curios or relics of museum interest may be accepted for mailing without regard to 12.1.3 through 12.1.6.

c. Air guns that do not fall within the definition of firearm under 12.1.1a that are capable of being concealed on a person are mailable; but must include adult signature service under 503.8.0. Mailers must comply with all applicable state and local regulations.

d. Parts of handguns are mailable, except for handgun frames, receivers, or other parts or components regulated under Chapter 44, Title 18, U.S.C.

e. Mailers are also subject to applicable restrictions by governments of a state, territory, or district.