The M3 scanners can be configured via the ScanEmul app installed by the manufacturer.
The settings are detailed in this video, go back into the StoreFeeder app once set and perform a barcode scan.
On the device open the ScanEmul app
Add a new profile for StoreFeeder, ensuring the default profile is not enabled
Set Associated Apps - tick StoreFeeder
Output Mode should be None
End Character should be null
Intent Output must be enabled
Intent Action should be "com.sf.barcode.action"
If there is an Intent Category option it should be "com.sf.barcode.category"
If there is an Intent Delivery option it should be broadcast intent
Go back into the StoreFeeder app, select "I have updated the settings", click Start Configuration and scan a barcode 12345678.
This video is for an M3 SM10 but may be applicable for other M3 models that use the ScanEmul app.