A lot of people take Gifted for their characters for the increased stats. Small Frame also increases a stat, in this case Agility, but it reduces carry weight. I tend to use Small Frame on my snipers and melee characters if they use Gifted. If a character does not take Gifted, Small Frame is usually always taken together with either Good Natured, Fast Shot, or One Hander depending on my build.

However, I'm wondering if it is worth taking for characters that focus on heavy weaponry such as Big Guns and Gatling Lasers. Taking into consideration the ammo for these weapons tends to eat up our carry weight, the weapon itself, and we'll likely be wearing Hardened Power Armor in Fallout 1 (which weighs a whooping 100 pounds) or Advanced Power Armor in Fallout 2 (about half the weight of Hardened Power Armor in Fallout 1), and then there's also all the other items we'll be carrying, should I even bother taking Small Frame with such a character? Or can it still be a good trait to take even despite the penalty?

I generally think that small frame is a bad trait all things considered. To a large extent the nearly ultimate walkthroughs popularized it, most builds there have it, but it's like you said... the +1 to AG is not worth losing a trait slot and losing carry weight capacity. This is especially true if you're playing Fallout 1 big guns build. The power armor there is super heavy so you're going to need all the carry weight capacity you can get to feel comfortable. The +1 AG is not worth the squeeze, instead lower LU or PE by 1 or something.

And even in F2 it's a bad trait, you can technically play with lower carry weight, but there's no need to do that for a measly +1 stat. I'd much rather take bloody mess instead and have fun combat animations and retain the carry weight. I never take small frame.

A couple of times in the past, I've played as a dimwit in the first game, taking Fast Shot and Small Frame, using the Minigun with the .223 Pistol. Aside from the lack of companions to act as pack mules, I didn't really have any problems. I just didn't get to carry as much ammo.

what the hell are you talking about? This is a game forum, not the place to advertise yourself. Keep your comments to the topic at hand.

It's possible that's a bot? Look at the account creation date of May 2022.
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What's a bot?