New version of damage tester. This one has just one single gun, unlike the previous Mk3.5 (Type A) which had multiple guns.

Block mass 1

Block mass 900000

This version has a single cannon, and its purpose is to test a theory that game assigns fixed (range of) damage value--from high, mid, or low--to each cannon with every map restart.
Result shows that it wasn't the case, as it took the gun, a single gun, different number of rounds to destroy each block. Having said that, the range of possible damage seems to be fairy consistent with my previous testing result, which used separate cannons assigned for each block.
I still cannot tell the actual highest and lowest possible damage, and if the game can pick any damage from that range, or if it's chosen from roughly 1/1, 1/2, or 1/3 of that value.
With that said, now it's possible to get a rough estimate of cannon's kinetic damage from the very simple, formula:

Cannon kinetic damage formula (current, still just a guess)

Velocity * impactDamageScaler/(1, 2, or 3)

1/1 is the highest possible, 1/2 is mid, and 1/3 is about the lowest possible (some of the average damage result shows it's possible to go lower than that)
Big thanks to Farewellchiint for suggesting that mass scale of the block being hit might affect HP. I think it's possible it does under some circumstances, but it seems that's not the case at least with this testing method.

*I was able to store the number of shots taken to destroy each block by using memory storing smooth FT by Aweyer26
https://www.simpleplanes.com/a/DPcx27/Memory

Version history

Type A (multi-gun version)

V1
https://www.simpleplanes.com/a/VuZ4Pf/Damage-mechanics-test-4-explosionScale-impactDamageScaler-explosionScale-muzzl

Mk3.2
https://www.simpleplanes.com/a/e7vKx5/Cannon-Damage-Tester-Mk3-2-average-damage-calcurator

Mk3.5
https://www.simpleplanes.com/a/b7dEV8/How-cannon-damage-is-calculated-possibly-Cannon-damage-tester-Mk3-5-for-kine