Don't plan on making a return: some stores will accept returns on firearms and ammo, but many do not. Make sure to check before purchase.
You can always go to your favorite gun shop and buy a gift card instead of an actual firearm.
Research: ask the recipient what they want, talk to people the hunt with or shoot with, and pump their mom for information, the same way you would for any other gift idea.
Talk to the staff: as long as you aren't being cagey or wired for sound, most people behind the gun counter are more than happy to answer all your questions.
Another option is to surprise the recipient in the story. Bring them in and have the gun ready and waiting for them at the counter. Plus, it's a last chance to make sure you got them what they wanted.
There's always accessories: guns aren't the only gift gun people covet. There's weapon lights, iron sights, scopes, slings, and a million other add-ons that don't require paperwork or background checks. And most of those items can be returned with a receipt if they're not exactly right.