ZeroJunk,
As mentioned, Brownells sells a replacement shroud or a replacement shroud, pin and spring assembly. I suggest the assembly made by Gre-tan. It is very high quality and will reduce the "lock time" when fired. The shroud alone will not reduce lock time.
If you buy the assembly just take your bolt and the assembly to a gunsmith and I doubt whether they would charge to do the swap for you as it only takes 1 tool and 30-60 seconds. If you buy the shroud only they might charge you as the job takes 2 tools and 3 minutes.
LP