Higginson in it’s early days was selling repacked - bulk surplus military powder. They never plublisged load data - only referenced to commercial powder - exemple WC855 as H335 and were most of the time saying to start 10 % below H335 data.
I doupt load data exist for your powder..long shot... call Higginson, maybe the son got some of his father archives or old adds with infos..
Not completely true. Higginson's did publish load data in the form of newspapers they included with each order.
I actually helped Tom put together several load tables for different powders for several cartridges with different weight bullets. No pressures, just charges and velocities from specific rifles for comparison purposes.
Xelex was a product sold almost exclusively by Higginson's to International Firearms. International would often pick up large quantities of components, as well as other firearms related materials. Tom at Higginson's would repackage it for them, using green cardboard containers marked XL or Xelex. For instance, when the 6,5x55 chambered Swedish Mausers and Ag42B rifles first came into Canada, CIL/Dominion were in the midst of change. They offered old stock, loaded ammo but no more brass.
International made a deal with Norma to import several hundred thousand brass cases into North America to fill the void. Tom repackaged all of those cases into XL boxes of 20 for them and even offered them for distribution to most local gun shops in Canada.
The #55 powder you mention was very close to BLC2 and is very consistent in burn rate. It's almost ideal for cartridges such as the 223 Win.
It was made by Olin around 1971 and IS NOT CANISTER GRADE. It was developed for factory loaded 223 Rem and it's supposed to be great for cartridges right up to 30-06. I've still got some of it left but mostly save it for 223 Rem and 22-250.
BLC2 is just slightly faster burning than #55 and the data I helped compile for that powder for Tom is very close.
PM me if you have a particular cartridge you want to use it for and I will go back into my records for the data, I may not have what you need. I only helped compile data for 15 different cartridges, some obscure.
Using BLC2 data will give you safe loads for anything listed in modern manuals.
One thing, this is a "ball" type powder and it needs magnum primers to give consistent results.