The fact that the cops might not know does not make an illegal act legal. The question was whether shipping ammo to him would violate Connecticut law, and the answer is "Yes." It would violate Connecticut law. Unless:
The permit he is referring to is an ammunition eligibility certificate. It's a nanny state permission slip that allows the holder to buy ammunition, but not guns.
Next up is a "long gun eligibility certificate." That allows the holder to purchase rifles, shotguns, and ammunition for rifles and shotguns.
And then there is the "Permit to Carry Pistol or Revolver." Holders of a Connecticut pistol permit can buy any type of firearm, and any type of ammunition.
If your friend has a pistol permit or one of the other certificates, he can send you a photocopy or scan of the permit and his driver's license, and you can then send him ammunition. If he doesn't have any of those documents, he cannot legally procure loaded ammunition by any means while he is in Connecticut. This is what the on-line ammo (and magazine) vendors do -- they have the customer mail or e-mail a scan of their permit and driver's license, and they maintain that on file for proof of eligibility.
What he can do legally is drive to Pennsylvania, New Hampshire, or Vermont and buy ammunition there. The law does not appear to address importation by the end user from out of state.
The text of the statute reads:
Sec. 29-38m. Sale of ammunition or ammunition magazine.
(a) For the purposes of this section and sections 29-38n to 29-38p, inclusive, “ammunition” means a loaded cartridge, consisting of a primed case, propellant or projectile, designed for use in any firearm, “firearm” has the meaning provided in section 53a-3, and “magazine” means any firearm magazine, belt, drum, feed strip or similar device that accepts ammunition.
(b) No person, firm or corporation shall sell ammunition or an ammunition magazine to any person under eighteen years of age.
(c) On and after October 1, 2013, no person, firm or corporation shall sell ammunition or an ammunition magazine to any person unless such person holds a valid permit to carry a pistol or revolver issued pursuant to subsection (b) of section 29-28, a valid permit to sell at retail a pistol or revolver issued pursuant to subsection (a) of section 29-28, a valid eligibility certificate for a pistol or revolver issued pursuant to section 29-36f or a valid long gun eligibility certificate issued pursuant to section 29-37p and presents to the transferor such permit or certificate, or unless such person holds a valid ammunition certificate issued pursuant to section 29-38n and presents to the transferor such certificate and such person's motor vehicle operator's license, passport or other valid form of identification issued by the federal government or a state or municipal government that contains such person's date of birth and photograph.
Source:
https://www.cga.ct.gov/current/pub/chap_529.htm#sec_29-38m
I know -- it says no one shall "sell" ammunition. Does that mean you could
give him a few boxes of ammo? I don't know; I'm not a lawyer. Section (c) of the statute makes multiple reference to "transferor," not "vendor" or "seller." Based on this, I think it's safe to conclude that the legislative intent is that nobody in Connecticut can obtain loaded ammunition without holding one of the aforementioned permission slips. I had a friend (now deceased) who was an NRA training counselor in Connecticut. He told me that the State Police were interpreting this law so strictly that when NRA instructors taught the metallic cartridge reloading class, they weren't even allowed to let the students take with them the cartridges they (the students) had loaded in the class. Personally, I wouldn't take the chance.
The other (and, IMHO, better) work-around is to reload. The law defines "ammunition" as loaded cartridges; it does not address components. Your friend can buy all the powder, projectiles, brass and primers he wants and load as much ammunition as he can possibly shoot without being subject to the provisions of this law.
In the long term, your friend should get a pistol permit. It wasn't stated if he shoots rifles, handguns, or shotguns. If it's handguns -- he can't even take a handgun from his home to a range for practice unless he has a pistol permit, so it really behooves any firearms owner to get the carry permit. That also allows the purchase of handguns, long guns, and ammunition, so it's the most useful of the several permission slips Connecticut offers.