I rounded to the mid point of your suggested numbers so 25 Piercing, 25 Explosive.
Against Armor
25 Piercing(1.5 modifier) = 37.5
25 Piercing(.3 modifier) = 7.5
45 damage per shot
360 Damage per clip
Takes 3.2 seconds to shoot this
5.5 seconds reload making total rotation 8.7 seconds
360/8.7 gives us a DPS of 41.38
This makes it roughly the same as a light carronade which has a dps of 35.02 against armor. Against a Junker's 700 hull armor, you're gonna need 2 full clips (17.4 seconds) to bring down armor while praying their isn't a mallet hit done.
Lets give the repair guy some mallet hits. Lets make em smart and he mallets after the clip has been fire as to not waste. Basically with 9 second mallet cooldown, and 8.7 seconds between clip starts, this can easily be done. Your Damage is now functionally 110 per clip till the last clip (you can't repair that which is down.
700-360(final clip)=340/110 (Dam per clip accoutning for mallet repair)=4 (rounding up as you use full clips.)
So thats 5 clips to break a Junker's armor which will take about 43 seconds.
For comparison a merc will take 18 seconds, a hades 12 seconds, a gat 8.5 seconds.
So now we have broken the armor lets look at the hull
Piercing 25(.2 modifier)= 5
Explosive 25 (1.4 modifier)= 35
40 damage per shot
320 per clip
Takes 3.2 seconds to shoot this
5.5 seconds reload making total rotation 8.7 seconds
320/8.7 gives us 36.78 dps. However, that isn't as important with hull kills as its about putting enough damage during the rebuild of the armor.. Lets keep fighting that Junker from earlier.
320 damage leaves the perma hull 180, However, during that 8.7 seconds, can the Junker rebuild its armor? Yeah, we need 9 spanner hits and it takes less than a second between whacks so unless there is some serious slack, you can't one clip meaning you have to break armor again.