What, exactly, is "pistol ammo"?
.223 or .308 for an AR pistol?
410 for a Judge?
.45LC or .38/.357 or .44 for a lever-action rifle?
.22LR for a 10/22 rifle?
30/30 for a BFR?
If there's a legal definition of "pistol ammo", would that not imply a corresponding legal definition of "pistol", based...
Sounds like dealers being bitches. "the ATF agent said ..." is a good excuse.
Take your business - ALL purchases - elsewhere.
And let others know who to avoid.
Given that logic, using a 30/30 lever gun would get you in more trouble too.
How many professional instructors and coaches, cops, prison guards, and private security teams use them?
"Remember what we told you yesterday? Well, that's no longer true. Here is our new 'interpretation' ..."
"No facts of the case changed, we just changed our mind. Have a good day."
Welcome into the future.
Get used to that. You'll be hearing it a lot.