Hodgdon’s website shows a ¾ oz load in the 28 ga Cheddite hull using 15.6 gr Longshot, a Fiocchi 616 primer, and the Remington PT28 wad. Using the Rio 28 ga hull in place of the Cheddite, I found some dishing in the final crimp. I bumped the shot weight to 335 gr (NSSA legal) and added a ½” diameter overshot card, resulting in perfect crimps.
From a cost perspective both Longshot and the Remington PT 28 wad have less expensive alternatives. Alliant Unique powder, being a bit fluffier than Longshot, was my first consideration since it would fill the case better and could eliminate manually inserting the overshot card. The Claybuster 5034-28HS B wad, less expensive than the PT28, was another choice. Looking at Alliant Unique loads in other hulls, I selected 13.7 gr and 14.0 gr of Unique as loads to be tested. Loads were hand weighed, packaged, and sent off to Precision Reloading for testing.
Along the way I had tried Cheddite primers but had to discard them for two reasons. First, my three Citori O/U’s would pierce the primer when fired in the lower barrel resulting in firing pin erosion. Second, as some have said on various shotgun forums, Cheddite has adjusted their primer size to American standards. When fired in my Remington 1100 (both in 28 ga and in .410 bore), I would have occasional primers back out of Rio hulls and occasionally jamb the action.
Results from Precision Reloading testing show pretty much what I expected but wanted confirmation. I was looking at Alliant’s listed Unique loads in the Remington STS, which is why I selected the 13.7 gr and 14.0 gr loads to be tested. My Rio load was a substitute in both the hull and primer, but considered the Rio hull to have just a bit more volume, mitigating somewhat pressure increases that might have resulted.
Results showed the 13.7 gr load had a higher variation in velocity and pressure, but the 14.0 gr Alliant Unique load seems to have settled in nicely. Average velocity was 1230 fps with a Standard Deviation of 4 fps and an extreme variation of 11 fps. Average pressure was 11850 psi with a Standard Deviation of 239 psi and an extreme variation of 600 psi.
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