The space marines have a hole in their army, the have APCs but no actual tanks. The Gladius is a cobbled together mix match of existing tec with a BFG stuck onto the front. It may not be the cutting edge like the repulsor, but it makes a lot of big holes.
This thing is about the size of a land raider.
As much as I have to learn about the lore, Ive been doing my home work. I feel as this should check out with the lore, but please correct me if not.
Also, as always, I do this for no profit. You can order these via the apps below. Make sure however to take a picture of it (and it painted if you like it) and post it. That is what enjoy most.
PS: the long gun has a muzzle break that is a remix, but I have lost its origin. I am looking for it, if you know though, comment so I can give credit. Right now its 4 AM and I need some sleep, the search goes on tomorrow.