Jerry,
Sorry to learn of your bad experiance using Gauge Mates. I use them often in 10-12 gauge reduction and occasionally for a 16-20.
Gauge mates fit in all my Parker and LC Smith 10 gauges without problems. They do not fit in a Spanish made Zabala Hermous 10 gauge magnum that I own. The reason is that the rim area of the chamber is cut to SAAMI minimum or perhaps even a little less.
I had to have one Parker's rim are enlarged a bit. It is a 12 gauge in the 68xxx serial numbers and didn't want to shoot any reloads. Upon firing in a larger chamber to include the rim area, the shell head/rim will expand to fill the void. Any reloaded haul caused the action to only close using much force.
The 12 gauge's hard closing prompted me to send her to the gunsmith. At the time I wasn't completly certain of the cause but I correctly guessed that it was the rim area of the chamber.
Your Parker may have a slightly undersized chamber, rim area, or even a shorter chamber that causes the Gauge Mate not to properly fit.
As for reloading hulls fired in the split version Gauge Mate, I can usually get 4 to 5 more 6000 PSI loadings from them. I will reload a AA or RXP hull until it looks like it will split in the loading press. This isn't optimum but... I've been collecting black hulled Remington bargin (sold in 100 packs) hauls as load, shoot, and throw aways!
Hope this helps. If you don't like you Gauge Mates offer them to another member in the Member's Only for sale section. They won't last long
Mark