That might change it a bit - especially since Joker shoots at a decently rapid rate. FTR, his frame data shows that
he shoots the Aerial Gun Down shots at frames 7 / 21 / 35 / 44. The longest interval is 14 frames;: since Smash runs at 60 FPS Joker shoots another bullet - at his slowest pace - every 1/4th of a second pretty much.
I used Aerial Gun Down specifically as a reference point and because it's effective at gimping recoveries (a bit too effective before a patch took away its diagonal shots) - other Gun attacks are faster, with the Spiral shooting every 3 frames (1/20th second). That wouldn't be realistic with a rifle, but hey, anime characters can do feats like stopping bullets, so what do I know about anime gun physics? (
)
The rifle might have a good trade off here where its rate of fire isn't nearly as much and might not have as fast start up as Joker's gun, but much more noticeable knockback to encourage using the rifle with more precision.
(Sidenote about Gun: Gun gives Joker
infinite directional airdodges as long as the move's used. That's another aspect of Gun that quite a few people have complained about,
such as in this podcast. That's something that A) I'm honestly surprised Sakurai have not done anything about and B) would have to be adressed with a rifle involved, IMHO.)
Still, I'm a fierce proponent of making Olimar's animations more distinct (yes, this would be really difficult to do - he's tiny - but more exaggerated body movements wouldn't hurt) because it's really bloody difficult to tell apart his forward smash from his side B / grab.
The intent with that nerf is worth remembering. The nerf was very likely done in order to make sure that
Chrom's suicide KO confirms did not kill the opponent first as often as it did when Ultimate released. Chrom's consistent hitboxes also was a major reason since he could confirm Jab -> Off stage Up B in a lot of scenarios (and still can IIRC). Roy, by contrast, does not have a suicide KO.