The title says it all, is an FFL a requirement to sell ammo?

 No

If you are manufacurimg ammo for resale, I believe you do.

ETA: ...and also likely if you are “in the business of” selling ammo.

Selling your personal stash of factory ammo - no.

Selling reloaded ammo - yes

Bulk-selling pallet level ammo as a commercial enterprise - don't know

No you do not have to be licensed to sell small arms ammunition.

Selling Small Arms Ammunition

[18 U.S.C. 922 (a)(1)(B); 27 CFR 478.41]]

Reading is fundamental.. you can not manufacture ! So the answer is yes and no ! Depends.

Reading IS fundamental. OP only asked about selling:

The title says it all, is an FFL a requirement to sell ammo?

Dave is correct.

I have a good fundamental reading skills, the OP never asked about manufacturing, he asked about Selling!

So the answer as outlined by the BATF website is NO!

This is what I am looking for.
Thank you guys! I find this section of the site to be the best. Because you guys dont bullshit around

BTW,

Does anyone happen to know or can recommend a place to buy ammo in large quantities to sell online? like sgammo?

You will need to be buying from distributors to get the best prices and that involves a lot of money and a lot of time to get the best prices, it is difficult for small shops and home based people to compete with the big online retailers who can afford to sell for a couple of pennies of profit and still survive.  But start looking for distributors who are willing to sell to smaller accounts and see what you might be able to come up with.

Unless I could sell hundreds of thousands of rounds a month, I would never even consider selling ammo, I can make more money cutting 1 barrel than I often times can on a couple of thousands or rounds of ammo.

Others may have different experiences, but I have never been able to make ammo sales pay off for me.

They buy from manufacturers directly most likely but maybe distributors. It’s not a easy game to get into. Wonder what product allocation looks like now.

Thank you guys for your sincere answer on the matter. I'm just basically researching at this moment if its worth my time or not. I've been having an itch on starting an online business for some reason but don't know what, since most of the accessories you can get at Amazon with free 2-day shipping, so I'm looking at the alternatives. I noticed RSR Group sells ammunition and at one point I was going to put in an application with them but for some reason I forgot. A lot of comments around the web say they have good prices compared to other distributors, so we'll see.

The major vendors buy directly from the importers (for imported ammo, obviously).
PW Arms in Redmond, WA is an importer of ammo and firearms.

Might want to consider gunpowder and primers then.  Guns, ammo, accessories are a pretty saturated market, with seemly low-margin returns.  But primers in particular continue to be fairly high-priced; more than it seems like they should be.  Gunpowder has come back down some too, but also seems a touch overpriced.   To my eye, the most overpriced on-line gun related item right now, is primers.  Which means there's room for to break-in with competitive pricing to shake that up a bit.  Possibly bullets as well; the price-ratio of basic bullets respective to their loaded ammunition still seems a touch high.  But again, of everything, it's primers that seem the most overpriced still.

Not that many factories make primers, so you might have a hard time finding a supplier, but that's where I'd poke around first.

@lazyengineer thanks for bringing that up. I'm going to try and find out where can I get those things. I'm assuming that by selling gunpowder there is going to be some sort of permit. I'll look into that.

I don’t want to make assumptions but my guess is at the volume you will be dealing with it will be hard to be competitive.

I worked at RSR for a few years and could frequently find ammo for less than our cost online.

Things to consider for the OP.
#1 You can only ship Ammo UPS or Fedex NO USPS!  Ammo is heavy! Till you have volume shipments UPS and FEDEX are not going to be offering you better rates.
#2 Buy enough powder to sell online you would need to be a different league!  Buying powder buy the truck load direct from Alliant, Hodgdon, Western, and Capstone.
Then you get into the storage of powder and primers.  Plus you need to have an account with FEDEX or UPS plus the Haz Mat Training! Then add the Haz Mat tag cost to the order and well between the shipping costs and HazMat Fee that the consumer would be paying they have to order enough powder to make it cost effective.
#3 Many of the big boys require FFL, Store Front, and other issues.
#4 Inventory at low prices COSTS MONEY and again warehouse area.
And, places like Olin - Vista Outdoors (Federal, CCI, Speer) they like contracts!  Same as Hornady.  And, min spend to get in the door is ranges from 100 to 500K

There is no way to make money buying powder and primers from large wholesalers because you would have to compete with places like Powder Valley.
Unless the powder come on a pallet on commercial truck the limit is 100# of powder.  And, UPS and FEDEX is 50# limit per carton

Then there is collecting sales tax on shipments at least to 4 states OR WA PA and MN let alone your own states

No offense but if you're not already into this business, branching into it, or are already into the importation and logistics along with commerce sales... I would say that your "I woke up and felt like I should have an online business" is a terrible idea.

RSR wont give you access if you do not have a store or an FFL.   The big ammo stores do not buy from RSR or those guys, many have importers licenses or are already working with large importers and have warehouses the size of Costco.... aka, buying truck loads.  You're going to be looking at the very large importers and manufacturers and they wont bat an eye if you aren't buying by the truck load.