Lead is only really soluble in very acidic soils. In alkaline or neutral soils (pH > 6.5), it's very stable and not likely to be taken up by plants. Additionally, the more organic matter you have in the soil, the less available the lead is to be taken up by plants (it's bound and held tightly by the organic compounds in the soil).
If you're planting in a raised bed, use plenty of compost and don't worry about it, unless you live somewhere with very acidic soil. If the beds are 8-12 inches deep, most vegetable plants won't send many roots down to where the lead pellets are, anyway.
Also, the amount of lead you're talking about is pretty miniscule. A hundred .177 pellets is maybe 60 grams of lead. Even if it were powdered and distributed evenly in a garden bed, it would still be what is considered "low" lead level for soil. A cubic yard of soil (the amount in a 4x8 raised bed 10 inches deep) is about a thousand kilograms or so. 60 grams/1000 kg = 60 ppm. Anything less than 150 ppm is considered very low for soil lead levels.
