Hi Allen and welcome. Although pump actions are more reliable, Semi-Auto versions can have their reliability enhanced greatly by storing the shotgun with the bolt locked back. This conditions the bolt spring so that it more reliable cycles shells of varying power. Stiff bolt springs are the number one cause of malfunctions in semi-autos until broken in. This will speed up the process. Cheers, stay safe and enjoy!

It’s been said that pump actions are more reliable but I use both.

The 20 Gauge and Bullpup Factors:
20 Gauge: A 20-gauge shotgun is a viable and effective option for home defense, with plenty of stopping power with appropriate buckshot loads. Its primary advantage is less recoil and a lighter weight compared to a 12-gauge, making it easier to handle for a wider range of shooters, which could lead to better shot placement and more practice.
Magazine vs. Tube-Fed: Tube-fed magazines are generally considered more reliable than detachable box magazines for shotguns.
Bullpup Design: Bullpup shotguns (which move the action behind the trigger for a shorter overall length while maintaining barrel length) are compact and maneuverable, great for tight indoor spaces. The specific design, whether pump or semi-auto, will still follow the general reliability principles listed above. The Smith & Wesson M&P 12 is an example of a reliable pump-action bullpup.

Hi Allen, Both pump-action and semi-automatic bullpup shotguns have their strengths. Pump-actions are typically more reliable in tough conditions and offer versatility in ammunition types. Semi-autos provide quicker follow-up shots but may require more careful selection of ammunition to ensure reliability. Be sure to use high velocity shells with a semi-auto and it should be reliable. Test a box before stocking up to make sure it will cycle & feed properly, and you should have little to worry about.
Stay safe & have a great day!

I have always heard pumps are more reliable than a semi. But I have never had any of my semi auto shotguns fail me.