Looks like the 9 on the assumed 29 just might be the g for grams; therefore, a 2 gram load?

So 2-piper is correct as for a 12 bore stamped with 2,2 g Sch. P. over 32g Blei a proof load is 4,4 grams of Schultze & 42,7 grams of shot.

Kind Regards,

Raimey
rse