We tried the garrett ammo stateside.
On par with the buffalo bore ammo that is available in canada now in price and performance.
I think wanstalls carries bb ammo.
The 45-70 is a special purpose firearm.
We owned a couple of marlin 1895s and got rid of them in favor of flat shooting 30 calibre rifles (308, 3006, 300 win mag) that are more suitable for the +300 yard shots we sometimes get in the flat open timber clear cuts of northern ontario.
It's a long drawn out process getting the clearances and import permits and approvals from natural resources canada.
Took 3 or 4 ears of beating back the red tape monster before bb was approved.
Cheaper to hand load your own so you can tailor make it to your specific requirements.