Part of the problem with using Ancestry or the other big data vendors is that they group different sets of records under "umbrella" titles that don't correspond to the titles used by the repositories that actually hold the records. So when you see a blog post it's important to read the description carefully to see if the author is telling you Ancestry's own name, or what the repository calls the records, or both.
If you are unfamiliar with archival materials, these links explaining the principles of archival arrangement may be of interest:
- How The Records are Arranged -- a video guide (and transcript) from The National Archives (TNA) [the archives where these two AO series are held, in the UK]
- Principles of Arrangement by Theodore R. Schellenberg, web version of Staff Information Paper Number 18 (1951), from the US National Archives (NARA)
Once you follow the directions in this answer and find the home page for each Ancestry database, the search box for that specific collection will be 'front and center' -- but there are other valuable things on the page. Underneath the search box, you'll find a section called Source Information which will say where the original data comes from (at least, we hope so -- this section can be inadequate for the compiled databases).
Ancestry.com. UK, American Loyalist Claims, 1776-1835 [database
on-line]. Provo, UT, USA: Ancestry.com Operations, Inc., 2013.
Original data: American Loyalist Claims, 1776–1835. AO 12–13. The
National Archives of the United Kingdom, Kew, Surrey, England.
Looking farther down the page, you'll find an About section that will give you information about what you might be able to find in the records and other notes on coverage.
From the search box on that home page for your desired collection, you can search that database directly.
However, bear in mind that not all indexes are perfect. Crista Cowan's YouTube video Some Genealogy Records Have No Name shows examples of how to find entries in a database that don't have names attached to them.
But if you want to see the material referenced in the earlier question, the easiest way to get there is not to search, but to use the browse function, which is in a box to the right of the screen, above the boxes for Related data collections and More Help.
Let's recap. We want to find this group of records within Ancestry's database:
"American-Loyalist Claims Series II (140) Miscellaneous
The author says we should expect to find:
... Claims for Losses in Upper Canada after the War of
And here's where she found them:
This specific (and valuable!) list of those
filing claims is dated May 1824 and begins on image 15 of 228. It ends
on image 49 at claimant number 2054
UK, American Loyalist Claims, 1776-1835 contains two different series of claims, one from Record Group AO 12 and one from Record Group AO 13.
- Go to the browse box at the right hand side of the screen. We have a choice of A012 which is Series I, and A013 which is Series II. Select AO13 from the drop-down box.
- Scroll all the way down until you find the Miscellaneous Claims. You want Piece 140: Miscellaneous, 1801-1835, which is at the very bottom of the list.
Click on the link for Piece 140 and then (if you have a British or World Subscription) it will take you to the image viewer. Next you'll want to take a look at the controls at the bottom of the screen -- I have a screenshot of just that part of the screen below. (I don't have access to that particular collection so this picture of the image viewer comes from a different database, but the function is the same.)
You now have two choices for how you want to navigate. Since you know the actual image numbers from the blog post, you can enter the image number box to get to image 15, and then step through the images to look through the roll until you reach image 49 -- or you can use the green icon that looks like a piece of film to open the filmstrip and navigate that way. (But see disclaimer below.)
This is essentially the same process you would have done in the old days, when everyone looked at microfilm on a microfilm reader. Because of that, it can be helpful to look for reference materials that describe how things are arranged on the microfilm. For example, NARA (the US National Archives) usually has a document at the start of the microfilm explaining what's on the film and how it is arranged. If it's not there, you can look for the microfilm roll number in the Source Citation information and see if there's a document about the microfilm on NARA's website.
- While it us sometimes useful to have the image numbers that you or someone else has looked at, we can't depend on them to be permanent bookmarks for the image we want. Both FamilySearch and Ancestry add images to their databases, so the image numbers may change at any time.
- We can't depend on Ancestry or FamilySearch to correctly identify which microfilm roll the digital images have come from. Both have been known to make errors, and Ancestry has been caught out re-arranging digital images to suit their own purpose.
Because of these things, it is important to understand (as much as we can, and they don't always make it easy for us) the nature of the original material that the big-box vendors are offering to us.
If you don't understand what you're seeing, it's always a good idea to ask. Most experienced genealogists have had the same difficulty at one time or another, so they'll understand.
Finally, to get back to your original question -- I don't know of any way to restrict the search to only the items which are found within A0 13. If you want fine control, you'll probably want to know the arrangement of the records in any case, so don't hesitate to browse.