The only bipods I know about are the Harris bipods. They attach to the sling swivle stud. The set up I have on my rifle is two studs on the front of the stock. One for the sling and one for the bipod. I think that Harris is making a bipod attachment that also has the sling swivle on it, but I'm not sure. The two stud method works well for me and is the set up thats on my sniper rifle.
I agree with the above post and will also confirm that most if not all of the harris have a swivel on them so you can attach your sling to it. The two swivel post system mentioned above works much better.
I've got a Harris. It attaches to the swivel stud. To understand how it works, put your thumb and forefinger together and imagine half a sling stud on each side. With a Harris, you turn a thumbscrew to loosen up the two fingers. You pinch to open them, slip them over the stud, and tighten the thumbscrew to secure it. The screw retracts the fingers up to the bipod, which tightens them into the swivel stud and pulls the bipod into the rifle in the process. There's a spot on the bottom of the bipod to attach your sling to. It's extremely easy to use and you can attach or detach the bipod in seconds.
I've seen Rock Mount brand bipods in stores, and it looks like they use pretty much the same process. I don't know how well that brand works, but my Harris is fast, easy, light, and rock-solid.
I must admit that I have missed a big game animal with a rifle. And not only was it a bull elk, it was the largest bull that I have had in my sights with a tag in my hand. But, as with most "missed shot" stories, I have an excuse. Moisture doesn't really ever bode well for hunting equipment. When moisture (either rain or snow) gets into a firearms barrel, nothing good takes place. A couple rain drops down there can change the point of impact drastically and a barrel jammed with snow after a...