I'd imagine this was possibly one of the more common pressed patterns for custards - I have a couple and they seem to be identical to those posted here - one of mine has a very sharp pontil scar.
Looking at collections of such items, produced over a long period of time, it might be true to say that the majority were blown, with handles attached separately, rather than mould pressed as an all-in-one object. Custards and jellies pre-date pressed glass by many years, and quality examples were still being blown long after pressed glass started.
Then again I have mould made custards - showing seams - with handles attached separately - so such objects seem to show the complete range of manufacturing processes.
As you'd expect, mould made pieces incorporating handles show seams, one of which almost always runs mid way in line with the handle for obvious reasons, since otherwise you couldn't extract the glass from the mould. As far as I'm aware it's the need to remove seam lines, by fire polishing, that gives rise to the pontil scar on these pieces where, subsequent to the act of pressing, the item would have been held on a pontil rod and returned to the glory hole for polishing. However, seams lower on the object, especially the feet, seem nearly always to remain visible - probably a practical issue - heating too close to the foot my have been unwise.
Not quite sure of the comment "The outer glass is rough and sharp." this may suggest these particular pieces were insufficiently fire polished ........... my examples have crisp moulding, but don't seem overly sharp.
Prior to around 1870, all glass that required finishing or fire polishing was held on a pontil rod via the foot, and whereas after polishing the scar was removed on quality items, some utility pressed pieces such as this custard were left with a rough scar - simple economics probably - although the majority of custards and jellies seem not to be left with a rough scar.
Subsequently, the gadget made the pontil rod redundant on many lesser quality items, which is why the underside of feet on some pressed glass (and many jellies and custards with blown bowls) show the 'Y' mark left by the shears............ I could be wrong, but the desire to avoid the sharp scar and consequent time consuming grinding polishing, appears to have been the reason for the change from pontil rod to gadget. Marks left by the gadget (on the top side of the foot) are seen only very rarely, although there are pix on the Board, somewhere.
As for dating these particular custards, I think the pontil scar is misleading us, and despite the date of the invention of the gadget, in my opinion is these date from somewhere in the first third of the C20 - not earlier.
The assumption has to be that for whatever particular reason their place of manufacture decided that using a pontil rod to fire polish was more expedient that a gadget.
And this give rise to an unanswered question......... how were these custards removed from the mould and attached to the pontil rod, bearing in mind they would have been red hot?? Might they have been made in an inverted mould to assist in attaching the rod??