I don't believe that it was made for a specific rifle - mainly because of the wide range of possible charges from 40-150 gr. I believe that it is simply an ingenious device made for transferring a precise amount of powder from the main container (flask) to the measure without dribbling away and losing a single grain.
Many flasks have screw-in interchangeable nozzles for dropping a set charge, and I've noticed that many BP shooters fail to observe the very important step of never charging the gun directly from the flask - lest a lingering spark set off the whole thing! Your device prevents omitting that important step and further allows you to be precise with how much BP you would like to pour down the barrel or into the cylinder.
I can't believe that there isn't a country of origin stamped somewhere on it. I have a similar No-Name flask - but with the standard single-volume nozzle - and it is stamped "India" on the bottom. I've also seen them stamped with China, Taiwan, and Ukraine. We usually see their slipshod junk, but there are quality craftsmen who work mighty cheap in all four places - just look at the high quality Ukranian tang sights for BPCRs.
As to the 150gr.....a heavy Hawken-type rifle in .56-.58 cal. might need that much powder. I usually load my .50 cal Hawken with 85-90gr. but the best, most accurate load is 105-110gr.
xtm
Many flasks have screw-in interchangeable nozzles for dropping a set charge, and I've noticed that many BP shooters fail to observe the very important step of never charging the gun directly from the flask - lest a lingering spark set off the whole thing! Your device prevents omitting that important step and further allows you to be precise with how much BP you would like to pour down the barrel or into the cylinder.
I can't believe that there isn't a country of origin stamped somewhere on it. I have a similar No-Name flask - but with the standard single-volume nozzle - and it is stamped "India" on the bottom. I've also seen them stamped with China, Taiwan, and Ukraine. We usually see their slipshod junk, but there are quality craftsmen who work mighty cheap in all four places - just look at the high quality Ukranian tang sights for BPCRs.
As to the 150gr.....a heavy Hawken-type rifle in .56-.58 cal. might need that much powder. I usually load my .50 cal Hawken with 85-90gr. but the best, most accurate load is 105-110gr.
xtm
We would need to bring George (LordSlashcat) along for the ride....he'd have a heck of a time keeping us straight and on point :mrgreen: 
