If you are in possession of his rifle why don't you just give it to him (through a registered firearms dealer to cover your arse)...problem fixed.
The point is: So long as the ex lives in NY, the OP and his wifle can't legally transfer that rifle to him. The rifle is not registered, it's too late to register it and no FFL in NY can legally transfer it. The only way for the couple with the rifle to avoid legal jeopardy would be if the ex went to them and took the rifle back. Then when the ex transports it to NY, it is the ex that has the legal jeopardy, not the OP and his wife.
Now, don't shoot the messenger - again (Gitem 12 talking to you). I didn't make the law or support it, just letting the OP (and others here) aware of the very restrictive nature of the SAFE Act and trying to keep the OP and his wife out of any potential legal trouble they probably don't want.
The point is once the OP writes him a letter to the effect sure We have it but if you want it I'll be happy to transfer it it to you or you can come and pick it up at a local FFL that is holding it for you etc. just let me know how you want it transferred. At that point the legal maneuvering stops and it puts the onus on the EX. What's he going to do take you to court after you said he could have it.If you want give him a time frame like 30 days or you are going to turn it into the police, sell it etc. Let him figure out he can't bring the gun into NY thats his problem.
