My lead sled weighs 23lbs, i never found the need to add 50lbs of lead to it, never had any scope issues other than a cheap bushnell scope taking a poop after the rear glass lens came loose from the glue.
The other rest i use is the caldwell tack driver bag rest and a wool sock stuffed with beans to put under the rear of the rifle stock. Just as accurate as my lead sled to be honest but theres still always room for shooter error with it.