Bullet keyhole / tumbling problem...BHW barrel???

[Drifter]

...there is no such thing as 'Type 1' or 'Type 2'. You can find two types of Grendel chambers because one is cut for a 7.62 X 39 bolt and the other is cut based on a 7.62 X 39 bolt with the bolt face recessed another .011 (?) inches. The only difference is the depth of the chamber, not anything else.

BHW has cut 264 LBC chambers two different ways, just as you describe. Whether correctly or not, BHW refers to the bolts as Type 1 and Type 2.

Here's a vid posted by BHW:

http://www.youtube.com/watch?v=DZncepUMgBg

It seemed worth mentioning since the OP has a BHW barrel, but I agree that the bolt is likely unrelated to the keyhole results.