Welcome to Nutz fromSEOntario! Great to have another rimfire Nutr. I’m sure there are options for Annie 64s. They will not be cheap or readily available. I think Woox out of Australia have some options for Annie’s. I have an MPR and the stock has been modified with added weight and texture with an Epoxy finish. It works perfectly but it’s not a chassis and seems more like a McMillan.