So I came across my account at Google Webmaster Tools and couldn't help but have a look through. To my surprise I hadn't submitted my blogger sitemaps to Google. I did so years ago for this colchambers blog so I already had a guide but I thought I would just have a quick check to see if things had changed and also because I had forgotten what I did in the first place.
AtomI found a good set of instructions in How To Submit Blogger Sitemap To Google Webmaster Tools? and followed them.
The only problem is that this describes adding only an atom rss feed. For colchambers I have submitted both an Atom and an RSS 2.0 feed. I forget why but in fact it proved useful. The atom feed had two errors yet the RSS 2.0 feed had none.
I see them as backups. If one feed has errors the other will work fine. The sitemap tools have facilities for hundreds of sitemaps implying that there is nothing wrong with adding multiples. So that is what I did.
To add this additional site map I simply used what I tried adding /feeds/posts/default at first in the way suggested for the atom feed. This worked fine but only returned 25 responses. I expect google works fine with this because it's just returning the most recent items but since the Atom feed could return 500 I wanted 500 in this feed too.
To do this I used the query parameters reference of the Blogger Reference Guide to find the Google Data API query parameters and ended up with /feeds/posts/default?start-index=1&max-results=500.
This resulted in each sitemap submitting the same number of articles. Currently each sitemaps is shown as an atom feeding but they are still pending. I'll see if this changes when they are accepted. I compared with colchambers and the sitemaps there are categorised correctly.
I hope this helps. Maybe you have a better way. I am not sure if the max results is required because colchambers seems to have been working fine with the standard feeds but then I haven't really researched and analysed this area thoroughly.
At least I have now submitted my sitemaps to google. I can see if this has an impact in traffic or any other discernable impact.