Hi George and welcome. No Sir. I tried them once in my 870P,could not get them to feed reliably. Cheers and stay safe!

I have seen adapters for mini shells. Look for one for the 870 20ga.

George, most likely no. From Aguila - ""We have received calls from clients stating that they have tried our minishells in their 870s with excellent results, and that they did not understand why we have always mentioned the potential cycling problems. To this, we would like to state once more that minishells will not cycle flawlessly in regular pump action shotguns, no matter how well some customers are able to cycle them."
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So, you can give it a try.
Stay safe & have a great day!

The only way to know for sure is to try. they will cycle in some 870 and not in others They make a adapter for the 12 ga i am looking for one for the 20