All,
This great bear has slammer head that gives a series of benefits to slams, and a gun that slams. Does it get the benefits?
I assume gladiator doesn’t give a benefit to momentum slams, since that specifies it connects to power attack damage rolls (which I’m pretty sure momentum isn’t)
I would say the Momentum slam gets the +2 bonus to slammed distance and the great bear can follow up to the distance the slammed model was moved.
Gladiator does not give a benefit to momentum because momentum is not a power attack.
Yes. Momentum slams models, and Grand Slam head gives you an extra 2" of movement when slamming models.
Yes. Momentum slams models, and Follow Up lets you advance toward the slammed model when slamming models.
Correct. This is not a Power Attack Slam, and Gladiator specifically references only “power attack” damage rolls.
Hope this helps! 
On second thought something came to mind, can the great bear move directly towards the target with “follow up” if the enemy model did not survive the attack from the heavy cannon? Because, how do you move towards a model thats no longer on the table?
That is exactly the reason that you cannot advance due to follow up Follow Up if you destroy the model with the attack.
Just wanted to give a heads up that this is indeed the confirmed interaction!
Thanks - glad I did get it right
I see a suprising number of people with momentum gun and reposition head: given this interaction I think the cheaper, better slammer head is the right choice. Slam further and follow up seems amazing.
As towards that, I’m actually not a huge fan of the interaction unless I’m gaining the extra follow-up movement out of activation. If I can manage that somehow, it is indeed a better ability than repo, but shooting, slamming, hoping it survives, and then following up can be a little tricky to use effectively all within the great bears activation if I also want to do melee work. It could be spicy in Boris potentially, but there’s a little bit of skornergy where you want the model to die to keep chaining boris’s feat, but you also don’t so you can follow up. It’s weird, repo can be much easier to use
Slammer head was such fun and very cool. Then became a joke when you can’t shoot and power attack any more.
Becoming the cheap head you don’t really want that also happens to work with the slam cannon.
That is certainly an opinion, and I would be happy to dissect and likely stridently disagree with that statement in a non-rules thread. 
But perhaps we should stick to rules in the rules question thread.
You can have the follow up out of activation. Once with “Ancillary attack” from Volkova, once with the spell “Avenging force”, once with Ilari’s feat and once with the spell return fire. Theoretically the great bear can traverse extreme distance with follow up, sadly there are many “if’s” like if you hit the enemy with RAT5 and if the enemy survive your pow16 attack and if the enemy don’t get stuck on something after 0,5 inch after being slammed.
Ok, now to make a list entirely around abusing this interaction and delivering a great bear to caster at lightning speed
Yeah, this was all what I was attempting to insinuate. There’s actually a decent amount possible with this interaction, there’s just a few things that make it unlikely
