Definitely the wrong nails. I was going for those, but felt like an idiot for even considering them. Thankfully I couldn't even find them, I guess because they're out of season here. I grabbed some 8" spiral framing nails. They have small heads though. Got some heavier non spiral 10" with bigger heads, but they're definitely a lot harder to get into the ground and I don't want to beat up my hatchet unnecessarily. Plus they're about twice the weight. I'm considering the 10" spirals with the smaller heads, the 8" go into the ground nice but they're a little on the thin side and with the small head if there was an extreme wind that bent the nail it would be much easier for my lines to fall off. I have some of those groundhogs. I didn't get around to actually trying them in the frozen ground though. They're short, the eyelet is small so you need to use a fine cord loop to use them and that ultimately becomes the limit of how strong the system is. The upside to having a loop is the line isn't going to fall off. But with a long nail you just make the angle sharp enough that the line won't be able to come off unless it rips.