Interesting. That seems odd, as 147 grain certainly isn't the most common 9mm weight. I have a Beretta 92 owners manual and it doesn't suggest what bullet weight to use, but in the specs it states what the weight is when fully loaded with 115 gr. NATO Ball, which implies they think that weight would actually be used in their gun.
The Taurus manual that covers all "Metallic Pistols" instead of just the 92 states the maximum levels of "hotness" you should fire in them with 9mm being given as 124 grain with a muzzle velocity of 1,225 ft/sec max. Again suggesting they might expect something lighter than 147 gr bullets to go through their guns.