There's a chance that they were in service with telescopes but were sold off without telescopes. There were roughly the same amount of rifles as there were telescopes, numerically speaking, telescopes went up to about 26xxx, which coincidentally is the approx amount of No4T's. The attrition rate of telescopes was greater than rifles so if we needed a telescope at Base workshop for an otherwise serviceable rifle, then we'd ask Ordnance for one. As they were not an issueable item per-se, (they were a 'starred item' or accountable item in their own right don't forget.....) there'd be a covering report with the indent request. The telescope would come in a long off-white/buff thich sailcloth type material bag with a tuck-in top flap (if you ever see one in your travels), tied at the top.
Telescopes/brackets could only be fitted at Base workshops (that's not strictly correct of course as some of the big Command workshops were really large Field workshops but were capable of Base workshop repair standards). The replacement telescope came from somewhere of course and that was most probably from an unserviceable or used rifle up for disposal languishing in Ordnance. And, as I say, in this case, that rifle now missing a telescope then became just another rifle! Thereafter the rifle would be marked as 'less telescope'