I found a couple of empty 12-gauge plastic Remington Express hulls in the storage room last night. Application of a rather dull hacksaw revealed this.
SP hulls, Remington Express.jpeg
One on the left is head-stamped REMINGTON 12 GA EXPRESS and has the "Hydraulically formed in the shell fiber base wad."
The one on the right is compression formed and head-stamped --REMINGTON--12 GA.
The Remington RXP compression formed 12-gauge Trap and Skeet shells were introduced in 1973 and the 20-gauge by 74. The 1976 Remington catalog still shows the Remington Express hull with the "Hydraulically formed in the shell fiber base wad." The next Remington catalog I've found that shows a full cut-away of the Remington Express shell is 1982 and it shows a compression formed hull.
1982 Reminngton Express compression formed SP hull.jpeg
So, the likelihood of running into the smaller volume fiber base wad SP hull in a reloading situation today is pretty remote.
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