Was looking at a 37mm launcher for smoke rounds and since they are not rifled like the 40mm are, what really is the difference between them?

Was looking at the side loading Spikes 9 inch, the B&T and the IWA.

From my understanding the tube length difference on these wont matter assuming its long enough for the case/shell you're putting into it because its not rifled. Assuming they're all side loading and can shoot the exact same 'round' is there really any performance difference between them?

What am I missing?

Unlike 40mm, there isn't a set standard for 37mm so ammo made for one launcher might not work in a different 37mm.

One of the reasons it makes sense to load your own.

I 100% was going to as I have a smoke recipe that puts whatever is available to shame.

Was just trying to figure out if there was any sense/value in going to just a cheaper Spikes over a $1500+ 37mm launcher.

Durability/strength varies wildy. I've seen some (CMP) launchers that you can bend the steel receiver rail by hand. Some of the spikes launchers have had the breech  locking piece shear off.

In general the 40mm launchers and the 37mm launchers based on them will be better quality and construction. These include the LMTs, Deftec, Penn, IWA, and B+T.

IWA is the highest quality, B&T is quality as well but is a bit weaker
Spikes is airsoft tier