Sorry if you see this a a repeat from the basic shotgun reloading site.
While I've loaded metallic cartridges for over 30 years, I'm new to shotgun reloading and need advice. I recently decided to begin casting and loading slugs, specifically the Lyman 525 gr (1 1/4 oz) sabot "pellet." When I bought initial supplies locally, the Lyman #5 Shotgun Manual wasn't available, so I got a 12 gauge "Load Book" which claims to include data from all powder manufacturers and some loading manuals, including data for the Lyman slug. "Load Book" offers caliber specific load data for a number of popular cartridges.
I loaded 30 rounds using Federal, WW and Remington cases with Hodgdon Universal Clays. I immediately had problems crimping the loads. They seemed too long, so I switched to a shorter wad. Fortunately, the weather was bad, so I didn't shoot. I the mean time, I'd ordered a real Lyman manual, and it came in. When I compared the "real" Lyman data to so called Lyman data listed in "Load Book", there was a 7 grain difference in max loads for Universal Clays loaded in Federal Gold Medal hulls. There was also a 5 grain difference in SR 4756 data. All three of the "Load Book" loads I'd prepared significantly exceeded the maximum loads in the Lyman #5 manual. Furthermore, the Load Book data lists 10,100 psi with 36 gr of Univ Clays, while Lyman #5 says you'll get 10,400 psi with only 29 grains of the same powder!
What is going on? I see that the 12 Gauge Load Book was published in 2004, and the latest Lyman #5 was published in 2007, but a 7 grain difference seems huge, with the latest data showing more pressure with 7 grains less powder. I'm not going to use the Load Book data, but should I raise a fuss with the Load Book publishers and Sportsman's Warehouse where I bought this questionable loading manual?
