Tool steel?

As this group is the fount of all engineering knowledge I wonder if anybody recognises the name 'Bullet AA' when related to HSS tool steel?
I inherited from my Father a box full of unused tool steel. There are various sizes which mostly have a ground finish and the manufacturers name or the specification etched on them. But there are several three inch lengths which are roughly 3/8" square with a black unground finish and with 'Bullet AA' cast(?) on one side. They appear very hard when touched on the grinder. They could have quite easily have come from the States as part of lend/lease.
I'm just curious to find out anything about them.
Thanks.
John H

John H wrote:
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It appears, from my restricted UK access to google books, that it was known in America as "REX AA", and was and may have been made by Crucible Steel Co. of America.
Herewith part of an advert from American Machinist, 1913
REX-AA Known in Europe as Bullet AA The result of many years of labor and constant striving to attain perfection in every essential feature. Every consumer of High Speed Steel will find it advantageous to use this brand. CRUCIBLE STEEL COMPANY OF AMERICA PITTSBURGH, USA EUROPEAN BRANCHES: London, S. 31-32 Borough Road. Berlin, Prenzlauerstrasse 27. Hamburger Frei- hafen.
Iterating our search,
"REX AA" decodes as T1 in "The Tool Steel Guide"
And T1 is listed here:
http://en.wikipedia.org/wiki/High_speed_steel
BugBear

wrote:
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BugBear, thanks for the info.
It certainly looks as though this was something that came to the UK with lease/lend.
JohnH