Ok here are the sleeve lengths for the Prince Charlie and Argyll jackets that are stocked by Lochcarron -- I am assuming these are fairly standard and so would be the same from other companies as well.

Chest 42 and 44 have 25" sleeves in a regular fitting. Short fitting is 1" less, Long fitting is 1" more.

Here is the full chart, with measurements being chest/sleeve for regular fittings:
36/23.5
38/24
40/24.5
42/25
44/25
46/25
48/25.5
50/26
52/26
54/27

Aye,
Matt