I'm going to start work on project Terrier soon.
I'm going to start out by picking up a 510 mini and then order a 50455 mag tube,spring,follower and barrel.
Then try to find a good smith that will do the work of removing the factory mag tube and installing it on the 510.
The only two problems that I can guess at this point would stem from the bolt not matching up with the cut out on the barrel and the mag tube not fitting.
But I figure Mossberg would keep the mag tubes for their .410 in spec.
*crosses fingers* lets see how it turns out.