I’ve never bought a pack with consideration on how a bear can would fit. How I carry it is just a function of how best I can pack it and utilize the space in the pack balancing the entire weight content in my pack. Nowadays I use three different packs. My ancient Kelty D4 external, a McHale Bump, and a McHale LBP 36.
Sort of an exception to bear can consideration was my McHale LBP 36. For that pack, I bought the optional bear can straps:



I don’t use that Garcia can anymore. I have a BV450 and BV500. With the LBP36 I put the BV450 inside the pack, usually vertical. The BV500 is almost the exact same size as the Garcia, so it goes under the lid horizontally as in the picture above.
With my McHale Bump (picture below), a BV450 barely fits vertically. If I push it down past the top of aluminum stays it is hard to get out, as it fits very tightly. So I never use the much taller BV500 with this pack — and once in a great while I use the BV450. If I feel I need protection from bears I use the older Ursak, the yellow one, not the newer “all white.” I do always follow the regulations and use bear cans where required. Also, if I am with a group and we camp in a high use site known to have bears, I sometimes bring a can whether or not it is required.

KELTY D4 OPTIONS (which makes the Kelty awesome)
I can fit a bear can anyway I want with several options.
In the picture below the bear can (BV450) is inside the pack. You can see that it could be strapped to the outside of the pack on the top of the pack or below the pack bag where the sleeping bag, foam pad, and air mattress are currently strapped.

BV450

Above is a BV450 vertically, and you can see there is a lot of room around and above it. A BV500 is much taller but can fit vertically.
Below is a BV450 horizontally.

The larger BV500
Horizontally, it fits right at the top. The aluminum stays that hold the bag open won’t let it go down any further, so it sits on top of the rest of the pack contents. However, I could take out the stays and push it down — which I never do.



Above: BV500 horizontally with the top flap closed.
Garcia
The Garcia fits almost identically as the BV500. It sits a hair bit lower, but really can’t easily be pushed below the metal frame that keeps the top of the pack back extended.
