Single Shot tray Troubles

Purchased an aftermarket single shot tray for my Marauder .177 from a large on line airgun supplier. I removed the bolt to clean and lube it.

Checking my cleaning job I Looked down the bore from the back through the action. I could only see about 2/3 of the full diameter of the bore!

On examination I noticed the single shot tray was still in place. Removing the tray I saw a round hole! Checking with a friend who has a .22

Marauder, and an aftermarket single shot tray from the same suppler. He confirmed he had the same problem and also got better accuracy

using Benjamin magazines than when he uses the single shot tray. Since the tray holds the pellets too high, pellets tip when loaded into the

barrel. Yes they, will straighten some, but loaded straight into the bore helps accuracy.

I reworked my single shot tray using small rat-tail file, but stopped before completing. For better fit I plan to buy a 4.5mm end mill and cut

the tray's pellet groove to fit the height of the bore. Since the tray snaps in place, removing material off the bottom is not a good option.