Better bet (also from the fine folks at Trade-Ex) is just to load your own. They stock the Brass and the Bullets, both in bulk packs. Mailable.
The American 173-grain BT bullet was copied from the GP-11, early (WW1) US 173 ammo actually using Swiss-made slugs. Trade-Ex has the brass. YOU supply what no other factory in the world can supply: the immense CARE for CONSISTENCY which marks the Swiss ammunition out from any other MilSpec ammo in the world.
Everyone has specs for their ammo. The Swiss specs simply are very tight to start with and they STICK TO THEM.
You can do the same in your basement, just a bit slower.
There is a satisfaction to shooting a 1-MOA group with iron sights, using ammo which you loaded yourself, which cannot be bought, nor can it be described.
You owe it to the Rifle, and to Yourself, to gain this.