In answer to your queries, some of the bolts did have a very slight variation on the angle of the bolt.
If you see the enscribed number of your rifle it should be on the flat of the bolt which is what the engineers at P&H did.
The Santa Barbra bolt has round blast holes and is rounded where the p&h was elongated as a Military requisite, thats how you can tell the difference.
I should be able to get you some more information if you tell me the last 3 numbers and the letter shown on the bolt. It should be prefaced with two 00's. I know one of the original engineers and he has a log of serial numbers as and when they were developed who I tracked down when I wrote an article on the rifle comparing it to why it lost the MOD contract here against the L96 at the time.

The rifle barrel end was modified in anumber of ways he tells me for the various clients. Some wanted a threaded end to take the large moderator and others wnated their sight at the end, so there was no hard and fast rules on the production, it was a client based order from start to finish and hand built and crafted by the engineers there to you.
Hope that helps
Gil