In 1851, printers were not concerned with large margins on the stamps they printed. If you were able to examine multiples of these issues, you’ll notice on the plate layout that there is almost no white space from one stamp design to the next. In 1851 when stamps were imperforate and cut apart with scissors, all that was needed was a thin strip of white space for the scissors to do their job. It didn’t matter if the scissors slipped a little bit and cut into the stamp design. Most of the stamp was there and that’s all that mattered.
When perforations were added in 1857, they used the printing plates from the 1851 issues. Only Scott #37, 38, and 39 were new designs. But they followed the same plate layout as the 1851 issues – very little white space between stamp designs. Perforations made separating stamps faster and easier. Although the holes are small, they occupy most, if not all, of the white space between the stamps.
Take for example, Scott #38. In this issue in particular, the stamp design stretches side to side. There is no room for a margin of error. Even on well centered copies, the perforations always come close to the stamp design. Most of the time, the perforatons cut into the stamp design.
It wasn’t until the 1861 issues that the printers put a little space between the stamps. Compare Scott #71 to Scott #38. The margins on Scott #71 are still tight, but not as tight as Scott #38. The design of Scott #71 is a little bit smaller, allowing for some white space between the edge of the stamp design and the perforation holes.
Customers sometimes comment about the centering on the very early US issues. For a VF stamp, they expect lots of white space around the edges. Copies with ample white space on all 4 sides are very rare and usually grade VF-XF or better. On VF copies, the perforation holes should be clear of the stamp design or just touch the edge of the stamp design (which is normally the case with Scott #38).
The 1869 series and the large Banknotes of the 1870s have ample white space. Printers started putting a little more white space between the stamp designs. Finding well centered copies with ample white space is possible. However, prior to 1869, VF copies will show little, if any, white space around the stamp design.