Probably my absolute favourite tech from the artillery line has to be Shrapnel Shot. The first time I saw 3 units of experienced 24lb-ers unload a barrage of shrapnel shot against an enemy infantry line, decimating its numbers and instantly routing it, I almost made a mess in my pants

I may just not be positioning them right, but I've found puckle guns to be of very little use. I think you can build them from the 2nd/3rd highest rank of artillery building (don't recall exactly). When I put them front and center in my infantry line, they would kill less than my other artillery units, and wouldn't have near the same morale effect despite having a much higher rate of fire. Perhaps I just need to stick to using one at the flanks and get it experienced up a bit more, in hopes that it will really bring up the accuracy.

Rank Fire in the Infantry lineup is also VERY bread and butter, I usually practically rush for that tech as best I can manage, having one school going pure infantry line techs.

I haven't tried out the steam ships yet, but they have much fewer guns than the main SotL fleet, and when you get them, first rates also become available, so that makes it a bit more of a tossup.

Maybe could take 1 or 2 to try and keep them right on the enemy ship's rudder, but my naval micro just isn't that good yet.