some people are pushing 158 grain bullets at 1500 fps. is that safe for my ruger?
Yes, and no.
Safe, meaning will it blow up your gun? Yes, I think it is safe not to blow up your Ruger. Other than that, "no".
But there is a difference between "safe" and "useable".
The original 1935 level .357 load was a 158gr @ 1550fps from the 8 3/4" barrel of the Registered Magnum. (S&W later reduced their 8" barrel length to 8 3/8" to comply with an NRA match requirement, and that length has been their standard long barrel ever since)
You cannot get a 158gr to 1500fps from a mid size 4" revolver. #1) there simply isn't enough barrel. #2) The "strength" needed simply isn't there. And here, we are not talking strength to fail (blow up) but "strength" to operate normally.
The Service Six is the fixed sight version of the Security Six, and while it is beefier than a K frame S&W, it is still a mid size revolver, and simply isn't up to operating at the original load levels of the .357 Mag. Based on my personal experience with K & N frame .357s, and a 6" Security Six, if you push a 158 to the 1500fps level (or as close as you can get) in a mid size gun, it will fire, BUT odds are VERY high that you will NOT be able to extract the fired cases by hand!!!
SO, while loads at this level won't blow up the gun, they are not "usable" unless you accept the fact that you will need a small hammer and a rod to remove the empties from the cylinder.
Bigger beefier guns (N frames) will handle those screaming top end loads (worked up CAREFULLY) and still allow normal hand ejection.
As for what range to limit yourself to while hunting? I think the paper plate method works well enough. Use a regular paper plate. At any range that YOU can hit near the center of the plate (from the same positions you will use in the field) you are good to take game.
If you can regularly hit the plate somewhere (but not near the center) move closer until you can hit near the center. That should be your max range. 80yds or 40, or somewhere else, TEST yourself, and stick within what you can do.
Your Ruger will handle any standard .357 load you can buy. If you want/need something more than that, you should look into getting a different gun.