Why can you put muzzle breaks/boosts on semi-automatic weaponry?

[TerraNovaClick]

I.E the SAR or M92 pistol. Is there any reason why these attachments can go in, even though they do nothing?

[captainrussia]

attachments are slot based no?
So they can simply go in, because that slot is enabled on the weapon...
And they still add the effects (either all negative, or some positive). Muzzle break will reduce recoil on SAR and M92

[TerraNovaClick]

You can't put some attachments on some items, they aren't modeled for it. I.E: Flashlight on a Revolver.
Muzzle Break would not reduce recoil, that's not how they work. It literally would do nothing for a semi-automatic weapon haha. Maybe a leaded barrel.