I don't think anyone with a sane mind would try hog hunting with ANY air gun chambered in .177. That said, there are some very powerful precharged air guns out there. Around 1780 an Austrian gunmaker Girandoni developed a powerful .51 caliber repeating air breachloader (smoothbore) that held enough air for about 20 shots. At least the first 10 shots or so were ballistically comparable to .45ACP and more than powerful enough to kill a man at 100 yards. There were several specialist units issued with that gun who could provide accurate fire at a rate unheard of in the age of single shot muzzleloaders. Lewis and Clarke probably used the very same model on their expedition.

Today there are a number of manufacturers offering similar high power air guns. They're really popular in Asia and some other countries where access to firearms is very restricted but air guns can be owned legally (sometimes regardless of power!). Shinsung is probably the leading brand, they make a PCP rifle in .50 cal that packs a punch. It also makes about as much noise as a real firearm. People have used them to harvest all kinds of game and they could definitely take a deer at 100 yards even with less than perfect shot placement.