#no seriously...

Nah, you’re okay, and you’re right, this might be a little bit of a spoiler to the Genocide Route of my Underswap Take but, I’m going to answer this anyway. Lol.

All right so some of you might already know but, it is implied that Papyrus has access to Gaster Blaster back in Undertale. Papyrus would tell you during his date scene after you abort the Genocide Route by sparing Papyrus... anyway Papyrus would tell you (When you interact with the box of bones), 

Again, hinting Papyrus could have access to the Gaster Blaster but, he didn’t use it since he wasn’t trying to fight (Kill) you. I also remember that there is another thing of Flavor Text that appears when it’s your turn during Papyrus’s Neutral Fight. I’m pretty sure the line is, “*Papyrus prepares a non-bone attack then spends a minute fixing his mistake.” Now I might be entirely wrong and that probably doesn’t exist in the game (If this line does exist in the game, please let me know.) but that could be another hint at it.

Now going to Canonswap for a second, Papyrus is shown to also use Gaster Blasters in this piece of Artwork by Underswap’s creator, PopcornPr1nce.

Okay... so, some people might get mad at me for this, and some might call out for being a Colorblind Idiot, but I’m pretty sure Canonswap Papyrus’s blasters are Gold colored... soooo...

To answer your question, yes, Papyrus in my Underswap take DOES use Gaster Blasters and they’re Gold just like Canonswap Paps’s Blasters...

...many people sorta overlook the color of US Papyrus’s Not-so-Fun Guns and just make them White with Orange Eyes... I mean I could do the same thing but, I don’t know, Gold Gaster Blasters look super cool to me sooo... I’m keeping them like this. Sorry if you don’t like that decision. Also incase you’re curious, yes, Sans has Gaster Blasters too (They have a design that’s similar to Sans’s Mii Costume Gun thing, Minus the whole arm cannon part.), It’s just the two brothers RARELY uses them. Heck, Sans even rides on top of one sometimes when he’s too lazy to walk. 

Fun Fact: In my Underswap,  Papyrus’s blasters originally were just the normal Gaster Blasters but with Googly eyes instead, which was based off of the artist, Zarla-s’s take on Papyrus’s Blasters...