Not sure I agree with the spear chucking comment but it has some validity. Back then I don't think they had books with data in them.
It's pretty much NEVER safe to use a powder charge for some lighter weight bullet or shot charge with a heavier bullet or shot charge. That's just common sense. You didn't say and I didn't look it up in a book what the pressure listed for the 1-1/8 oz load is. If the pressure were down at say 8,000 then it's unlikely adding another 1/8 oz would be dangerous altho what the performance would be is unknown. But if the pressure is up around 10,5000 or more then it could indeed be quite dangerous to alter it in such a way.
You'll find that book loads do not always fill the hull and make a beautiful crimp just cuz the book lists it. What it looked like for them I some times wonder but at least you know it was a pressure tested thus safe load. There are lots of work arounds for when you want to use a load like that. First have you actually weighted your powder and shot to see how close your loader is dropping to what it's supposed to drop? Most likely one or both are dropping light and that's the reason your shells aren't filling out properly. That's a real negative of the tool you are using it just doesn't give you enough lattitude to adjust your shot and powder charges like a tool such as the MEC or Hornady presses among others do.
Weight both and if one or both is low you can try to figure a way to get them up to proper spec and chances are that will fix the problem. Going to Federal hulls isn't likely the answer as they have way more volume than a AA does. ACTIV has the largest capacity of all hulls pretty much.
Those of us who've been doing this seemingly forever use tricks like a bit of tissue over the shot to help fill it out and keep the shot in place or a drop of candle wax to seal it and hold the shot in place after you crimp the hull.
Of course there is always the obvious which is changing your load receipe to one using bit more volume either with wad or powder or both as needed. If you're not using the max powder charge then you can safely increase to that and it might fix it so might just buying a different wad of different size and using a receipe listed for it. But don't just switch components without regard to what's recommended in the load manuals and especially not if the pressures are already close to max.
Changing primers alone can alter pressure as much as 1500 pis or more, the same can be said for changing wads and just one more grain of powder might add from 500 to 1000 psi. If you alter several of those you could end up with a proof load or if the tolerances when the other way one with such low pressure it failed to work properly.
I've used a pinto bean in the wad below the shot to make a hull fill out properly and it's a generally accepted means to fill out the crimp without running pressures up as the volume is enough but the weight is not so much it adds to pressure and it will be pulverized and turned to dust on firing.
