Splinespider---well I've seen no activity here in about 3 weeks, so I assume that Bushmaster has not responded to your email. I sent them one on about Dec 23rd, it's now Jan 3rd and I have no answer as well. Just before coming back to work, I was out shooting and now MY bolt is broken as well-just like yours. The "tail" broke off at the groove.
I waited until after Christmas and re-sent the email. I called during the week between Christmas and New Years and got a recording saying they were closed for holidays. I re-sent the email a third time this morning.
I called this morning and finally got to talk to somebody there in the "service" dept. He told me they did not have any bolts for the old BAR10--which is about what I expected to hear. Like we said before, call 10 times and get 10 different answers from 10 different people. He told me I needed to call RRA and make sure they know that I needed the bolt for an old Bushmaster.
So, I called RRA and asked the lady for the parts/service dept. (At least a real person answered the phone, unlike BM) Waited quite a while and another lady answered who sounded quite young.
Explained what I had and asked if their bolt would work. She asked if I wanted the bolt or the whole carrier assembly,
and I told her I was asking HER if I needed a carrier assembly or just a bolt. She said she'd check and came back telling me I would need the whole BCG. I thanked her and said now that I knew that I'd just order on line. Didn't really feel confident enough to ask all the other questions I had about parts interchangeability, so I left it at that. Went to RRA website and sent an email with subject "technical inquiry" and I'll see how that goes. At least I got an automated response saying they got the email. Never got ANYthing from Bushmaster.
Now waiting to see about responses before I pull the trigger on the BCG. Even though you gave the part number for the new Bushmaster bolt, For the price difference I'll just get the RRA and I'll have something I can get parts for at least. Looking at the schematic, the extractor looks different from the Bushamster and don't know what else.