Pls, do NOT attempt to reduce the size of the translation by ANY means.
Secondly, what calibre gun do you have?
Third - if shooting pistols of any calibre or rifles up to .45 cal, 3F is the powder to use. In rifles over
45 cal., I use 2F as 2F in these has always shot cleaner for me in 50's and above. It has also given me better accuracy in various .50's, quite a number of .58's and my 14 bore rifle.
As Wade suggested - sell or trade the 1F for the appropriate powder for your gun.
Many shooters use 3F in all their guns regardless of calibre,.
If you or he insists on using the 1F (which many use in BP ctg. Guns) then simply increase the hole size in the horn and cut a new plug for it.
In order to achieve similar ballistics to 2 and 3F powders the charge of 1F will likely have to be increased approximately 25gr weight over normal 2 and 3F charges.