With the discontinuing of most plastic wads we've had for decades, it's getting impossible to create loads that were once everywhere. This is one my main reasons for continuing to research and test wads we've had for centuries. Paper, felt, fiber, etc. Natural wads.
I was unable to find any listed load in my old manuals for a 1 1/2 oz load with any powder still made. So I decided to test my own. I found multiple resources of loads listed with plastic wads, and I knew the general range I'd be looking in. I then tested them with my Pressure Trace II.
I make no claim to the safety or accuracy of this data. I am not a professional. Use it at your own risk.
The loads I tested are as follows
12ga 2 3/4" Federal Paper hull
Federal 209A
Bluedot 33 to 37 grains
(2) 1/8" 12ga nitro cards + (2) 1/8" 12ga felt wads
1 1/2 oz lead shot
fold crimp
These load beautifully. I love the crimps on paper hulls. You will notice I used two nitro cards. This is a practice I started with muzzleloaders. I tested how much hard card wads seal, using .050" thick card, and tested velocity. I found that .050" did not seal well, .100" makes a decent seal, .150" makes about all you will get, .200" was just a touch more, .250" was the same as .200". So a single 1/8" nitro card should be all you need, but I use two just to be safe. I used store bought 12 gauge nitro cards in this testing. You can use home made wads as I often do, and it will perform the same as long as you use somewhere between 1/8" and 1/4" worth of them. That's the great thing about paper wads is they are so forgiving. You can add or remove somewhat to adjust for stack height without changing the load. The felt wads I used were cut by me. Any felt wad will do. You can also use an equal height of cork or fiber. Just something compressible that will take up the space.
The results are not all that surprising, which is always good. I would say the biggest surprise when I first started doing these tests is how unremarkable they are. There was always this idea that paper wads don't seal as well, or that you need to increase powder to compensate for velocity/pressure, or whatever. Every time I do a test like this, I find paper wads pretty much do the same pressure and velocity as plastic wad data. I have never done a side by side with plastic though, but I probably should. I'm not going to average every single shot pressure today, so I'll round them. I did average the 36gr load. The velocities I did not pay too much attention to since I was focused on the pressure. Some of them were bad reads, so I did not get good averages. From 33 to 36 grains, velocity did not increase much at all. For all intents and purposes, at 34 grains, it was about 1180 fps, measured at 4'. The barrel was 28".
33gr- 10,000 psi
34gr- 10,900 psi
35gr- 11,100 psi
36gr- 11,866 psi
37gr- not tested
Now compare that to a load from Lyman. Yes the hulls are different, but pressures between Federal paper and plastic hulls, both with the same paper basewad, are nearly identical. Old manuals used to interchange the two.
12ga 2 3/4" Federal plastic, paper basewad
Federal 209A
34gr Bluedot
SP12 wad
1 1/2 oz lead shot
fold crimp
10,800 psi
1248 fps
So from what I'm seeing here, the book listed load is a nearly identical swap, with no real change in speed or pressure. It is definitely not a 10% change that used to be said. Of course I did not test the load as listed, as I do not have any SP12 wads. I'm going to load more of these paper wads at 34 grains and pattern test.