If am not mistaken the 721 and the 700 BDL long action are very similar. It is possible a stock for the 700 might fit. If not, Boyds makes a laminated semi inleted stock for the 721 along with a line of stocks for the 700. I believe Ram-line make a synthetic stock that fits. There are quite a few mfg out there and a google search for the stock might be in order. If your son is that clumsy the synthetic might be in order.
"I would not be an old man if I had not been an armed young man." JTJ
Patron Member NRA
"If you have always believed that everyone should play by the same rules and be judged by the same standards, that would have gotten you labeled as a radical 60 years ago, a liberal 30 years ago and a racist today"