Pressure Testing Results In--20ga Slug and Buck loads

[John in WI]

A few weeks back, I posted some info on some slug and buck loads I was working on. Being a weird configuration, I wasn't going to try my luck, so I sent them off to Precision for pressure/velocity data.
I guessed pretty well, I think. Still, for $50 I'll feel a lot better pulling the trigger with some numbers.

I used 3" pre-primed Ched hulls from BPI. The slugs were cast in 12mm sockets, which fit perfectly into cut down BPI un-slit wads (a non-discarding sabot setup). The buck was #1 and #F (.30 and .22).

I used WAA wads with the petals cut off over the powder. Over that, I stacked 2 layers of 2-#F and 2-#1 buck pellets (it comes out almost exactly to 1/2 ounce). Then, over that, I placed the socket slug/sabot combo. I weighed the slugs, since I didn't have any kind of sprue cutter. A few of them were around 0.56 ounce. These over-weight ones, I just bored a hole in the rear to bring it down to 1/2 ounce. They were then roll crimped right down to the slug.




Here's the Data:
Using 21gr WSF, Velocity=1336 Pressure=13154 (THIS IS ABOVE SAAMI!)

Using 16.2gr WSF Velocity=1124 Pressure=8464 (safe, but a little wimpier that I was looking for).

I know it doesn't exactly work this way, but if I average the values, 18.6gr WSF should get me around 1230fps, and 10,800PSI. I'm not sure if that's exactly right, but I am confident that would crank up the speed of the lower end load, and be significantly under pressure from the higher charge load.

I'm looking forward to some patterning. The first step was to make sure I could do it safely. Now to see if it actually patterns ok. A half ounce, .50 full wadcutter doing 1200fps would get something's attention.

[megasupermagnum]

Honestly, even 20gr should be safe. 20 gauge goes to 12,000 psi.

[John in WI]

You know, that's true. I should load up both, and see what the old pattern-board tells me is better. I think if the speed were above 1200, it would do anything I needed it to do. The more the better, of course, but not if the pattern sucks.

[megasupermagnum]

I wouldn't worry about the speed. Realistically the range those are likely to be accurate at, speed wont matter. They are at least as powerful as 357 magnum, and I'm sure quite effective for hunting.