Im really looking into getting my FFL. I was thinking can I possess "normal" AR15's, hi cap mags, other SAFE Act no-no's, etc. being that I can sell them to Law Enforcement? If so do I have to have them separate from my own stuff? Can I shoot them like to test before I sell it kind of thing?
This is not my reason for getting my FFL, just something I thought of. I'm doing it for hobby reasons and a little side money. I know I'm not gonna get rich, just something I've always wanted to do. Just something that crossed my mind.

I hear the ATF will bitch slap you if they suspect you aren't actually doing it for business purposes. As in if you don't make enough money they will probably shut you down. Because they do what they want. Zoning may hurt you. All the red tape of setting up a legal business. Business taxes. All things I've heard that are obstacles but I could be wrong.

But yeah you could "own" fun guns.

The term I heard(many years ago) was the ATF didn't like "table top" FFLs and worked to get rid of them.

you're not going to get a home based FFL unless you live somewhere upstate where basically every business is home based.
you have to be zoned for a business/firearms dealer.
you have to have a actual business/corporation/llc/etc. with a tax id.
they may require you to have a business bank account.
business must have insurance.
you have to have a state firearms dealers license.
most counties have their own additional firearms dealers license.
you need an additional state license to sell pistols, high cap.mags or assault rifles.
you can not get an FFL just to increase your own collection or to usurp local laws.
ATF will require you to have distinct and specific hours, no more appointment only stuff.
ATF will check in on you to be sure you actually are operating a business and not just scamming.

good luck!

While all of the above is probably true, it can be done in NY.
You can also become a manufacturer with an SOT to build and sell class 3 stuff as well.
Just depends on how many hurdles you're willing to jump through.

I have 3 SOT's in with 6 miles of my house that I deal with and buy class 3 shit from. it's most certainly possible, but the red tape is very thick and designed to be daunting unfortunately.