From trapshooters.com. A poster had some loads tested and this stood out.
The first load with a Win 209 and 15.7 gr of 20/28 is listed on the Alliant Reloading Guide as being 1200 fps and 9370 psi.
The second load with a Win 209 and 16.7 gr of 20/28 is listed on the Alliant Reloading Guide as being 1250 fps and 10,490 psi.
Hull: Win AA 20 ga
Wad: CB1078-20
Shot: 7/8 oz
Primer:
Cheddite
Powder: 15.7 gr 20/28
Ave pressure: 12,685 psi
Ave velocity: 1306 fps
Same as above except 16.7 gr 20/28
A
ve pressure: 14,022 psi
Ave velocity: 1354 fps
https://www.trapshooters.com/threads...esults.918249/
Cheddite Primer pressure spikes
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