I originally wanted to limit it to just a few, to make it more 'realistic' but I just have too many guns that I love. I'm currently carrying:

~2k 10mm rounds

~1.5k .44 magnum

~5k .45

~1.5k .308

~1k 2mm EC

~1k Shotgun Shell

~2k 5.56mm

31 Mini Nukes

Thank god around 14k rounds and 31 mini nuclear bombs weigh exactly 0

What calibers are you guys running with?

I just leave all of my ammunition in my inventory since it somehow weighs nothing. This is a but unrealistic, but it's a lapse of realism that I can appreciate. A lot of people don't realize just how heavy ammunition really is.

I was laughing during the pilot of The Walking Dead because Rick cleans out the armory at the police station and he's running around with a duffel bag with something like 6 rifles, 4 handguns, and 700 rounds of ammunition. In all likelihood, that duffel bag probably would have weighed about 250 pounds, but he's carrying it around like it's nothing lol

But...I can appreciate the fact that we just get to keep all of our ammo on us. My main guns are the .50 sniper rifle, a combat rifle chambered in .308, and a combat shotgun. I also sometimes carry Kellogg's Pistol, which uses the .44 rounds, but I never use it much. It's the gun that I want to love but just don't. I've always been more of a rifle person anyway.

I currently have like 12,000 rounds of .38. I've started using it as money just to offload some of it. I've equipped most of my settlers with guns that use .38 rounds and offloaded some to them, but I still have a ton.

basically the same as you ^^ only way less of each type

I also sell almost all my .38 and 5mm, as they're useless ^^

really struggling to find much 5.56 ammo for my rifle

Carrying them all, since there's no weight consideration. Never know when you might pick up a weapon that you'll need ammo for.

Ample containers where I reside means I keep ammo in ammo boxes, if it's a caliber I'm not loading out. Mostly just so the house is complete, with a full compliment of items, but also so I don't feel the urge to sell off any ammo types I'm not using.

Yeh I've got them all, no weight etc..

I need 2mm ECs, only got about 300 of that.

More & more I'm just going melee, and giving weapons & such to settlers.

Is there a good gun which uses .38? The best pipe rifle I have only does something like 27. So that gun is only for low-level enemies when I can't be bothered melee-ing, or distance is too great.

Just had an idea... The .38 grenade. All thats needed is say - 50 .38s, adhesive and steel.

.308 rounds, that's it. Overseers Guardian ftw.

How far into the game are you? I've got a few thousands rounds of 5.56 that I don't even use. It's like Kellogg's Pistol for this too. I want to love the assault rifle, but I don't. I really wish there was an assault rifle in FO4 that didn't look so goofy.

5.56 rounds become fairly plentiful after a while. If you weren't aware, this is the ammo that the machine gun turrets use. Turret salvage is always good salvage.

This is a good idea. I should really start doing this. I've sold a bunch of my .38 rounds because I wasn't using them, but I feel bad selling them. Selling ammo isn't like selling all of those extra Sugar Bombs or cans of dog food that I'm never going to use.

Not that I've found. Was using a Powerful (or Hardened) .38 Pipe Sniper for a bit, but it won't drop a Radstag before my companion will light it up with a combat rifle or grenade, so thinking about dropping it.

Not that I've found. I have a fully modded pipe rifle that I was using as my primary weapon early on in the game. The damage is so low that it's barely even worth using though. I still have it because of the nostalgia or whatever, but I haven't used it in a very long time now.

10mm, .308, shotgun shells, .50. Everything else becomes merchant food. Too much easy money, being able to stockpile weightless ammo by the dozens and hundreds. Maybe that's why this game feels significantly easier compared to New Vegas.

I have a 10mm and that's all.....I have various forms my go to weapon is the 10mm with extra limb damage

I have a 10mm pistol rifle that is semi auto that rips ghouls

and I have a 10mm that is plasma infused...

On big mobs I use explosives and mines.....and lure em to their death.

I was carrying around 13k .38 rounds until I finally realised that 1 round = 1 cap... Duh!!

I find myself using mines a lot more this time around. Enemies a much faster now, and it's good to have a fall back when you get rushed.

That fallback is called "combat shotgun modded for damage, narrow spread and hip fire accuracy and a really twitchy trigger finger".

I have a .45 sniper rifle, combat shotgun, and the 10 mm deliverer. My god, I love that pistol.

I have with me about 400 rounds of .45 for my combat rifle and 50 rounds buckshot for my shortened double-barreled. My Fatman is usually carried by my companion and currently I have 15 mini-nukes in my pants pockets.

Having the same struggles !

Haven't yet used the Assault Rifle as I barely find any 5.56mm rounds !

the ammo I'm carrying I'm most interested in are the six cannon balls I found in the castle, but I have no gun to fire them yet

I use a .308 sniper rifle and the Deliverer consistently, but still hold ammo for all types of weapons.

Might be time to sell it all and stick to what I like best.

Can anyone recommend and good 'secondary weapon' for when my rifle and pistol are not up to the task, say, in an all out firefight ?

It's a shame that pipe rifles quickly fall short when you go up the levels.

That being said, I have a pipe rifle that deals 15 fire damage, so have added the best automatic receiver ( still only 16 damage :/ ) and the quick reloading drum mag. Might last a few more levels if I upgrade the relevant perk, but i mainly use a .308 rifle and the Deliverer.

Since ammo has no weight it's not necessary to leave anything behind, which comes in handy when arming settlers because I don't have to look around for the right ammo.

I use 4 guns, so 4 ammo types are what I actually use;

-10mm (Deliverer)

-.45 (Automatic Combat Rifle)

-.308 (Sniper rifle, I have 2, a Hunting Rifle and a Combat rifle. I use only one at a time)

-Shotgun shells (Le Fusil Terribles, Combat Shotgun)

Piper has 3 different weapons she uses based on the situation we're in she use 2 ammo types

-10mm (10mm pistol & Silenced 10mm)

-Fusion cells (Laser Rifle)

Count me in, as I am carrying around an entire arsenal most of the time.

I pick up every ammo I find and trade it for the one(s) I use most. My current character is using a modified pipe sniper rifle with night scope and using a lot of .308. Ammo is my new currency.

I usually give all of my grenades to MacCready as he does much better with them than I do.

Yeah carry all ammo, never sell any - don't need caps and you never know DLC might make tat 5mm ammo vital!

I currently have at least 2000 of every ammo type that I use exepct for shotgun shells, never seem to find many of those but I currently have around 300

I carry 3 rifles all using different ammo and switch around them often so I'm constantly gaining ammo all the time.

I thought you actually meant weapons rather than ammo.

With weightless ammo it's more of a headache taking it out of your inventory than its worth. So for basic playthrough I don't bother.
For a modded runthrough it would be nice to see an ammo weight introduced, although I suspect that would just favour my stealth/snipe play method.

As for weapons and their calibre, I carry...

Combat Shotgun -short scope and suppressed for close up ghoul clearance
5.56mm Assault rifle -short scope and suppressed for inside buildings
.308 Combat rifle -long scope and suppressed for general wandering about and picking off targets from a distance.