Pffttt.
Nothing a bolter or other 40k weapon can't do better.
I'm just gonna assume you're referring to the corpse. In which case, not exactly. They're entirely different weapons with different means of inflicting damage.
First, the Bolter inflicts its damage to the human body primarily through kinetic energy. First, you have the round which penetrates with a KE of about 16-18 KJs. For those of you who are unaware, an .50 BMG fired by a M1 Browning has about 17 KJs of kinetic energy. So it would look something like this:
Except it would be fully automatic. So for someone whose wearing little to no armor, the first round would possibly overpenetrate and hit whatever is behind the target. For the person behind the target, you can basically expect their torso to explode. Second, in addition to the kinetic energy, you have the explosive round. If it's a shaped charge, you could easily kill 2-3, maybe 4 ranks deep with a bolter round. If not, you'd get 1-4 ranks deep, depending on how the charge works.
The phaser works by dumping subatomic particles into your body. On lower settings, this heats up the target. At higher levels, the NDF effect comes into play and we see most humanoids are disintegrated and things like rocks are blown apart. And yes, I do expect that Space Marines have weapons that can deal similar damage to Federation phasers. The thing is, those aren't their typical sidearms. They're either plasma rifles or rocket launchers or something similar.
Meanwhile, in Insurrection:
Just eyeballing it, that looks to be about three cubic meters of rock blasted apart. Assuming that's split between three phasers, we'd get about 318 kilojoules each. And we also know that from TNG's The Mind's Eye, that these phasers can dump much more energy than just 318 kj into a target:
LAFORGE: Rapid nadion pulse, right on target. Beam control assembly, safety interlock, both checked out. Beam width intensity controls also responding correctly.
DATA: Energy cell usage remains constant at one point oh five megajoules per second. Curious. The efficiency reading on the discharge crystal is well above Starfleet specifications.
LAFORGE: Yeah, by quite a bit. Ninety four point one percent efficiency.
DATA: Our most efficient discharge crystal typically fires with eighty six point five percent efficiency.
According to Data, the energy cell usage was at 1.05 megajoules per second. Although this one isn't a geniune phaser rifle, it's so accurate that the only place where they find fault is with the discharge crystal being higher than Starfleet specifications. According to Data, their crystals fire at 86.5% efficiency, meaning 13.5% of the energy from the phaser is wasted. Accordingly, that would mean that the maximum discharge from Phaser II and III would be
908.25 kilojoules. That's approximately three times more powerful than the display that we saw with the phasers in Insurrection (where three were used).
So yes, Federation troops do absolutely carry the firepower necessary to take out a Space Marine. In fact, they carry enough power to absolutely overkill a Space Marine. After a phaser on 16 is through with a Battle Brother, the chapter Chaplin will be collecting their gene-seed remains with a dustpan.
I'll also assume that since you didn't respond to my counterpoint on your claim of phasers not doing any significant damage, you've retracted that claim. Just so there's no confusion. If I'm wrong, correct me and present your own evidence.
