With their 76mm guns, torsion bar suspension and low silhouettes, the T20E3 and T23E3 were roughly comparable to the Russian T34, and the German Panzer IV so, on the basis that the M4 was becoming obsolete, the Ordnance Department requested the T23E3 and the T20E3 be standardised as the M27 and M27B1 in July 1943. However, the request was rejected and neither design was ever mass produced.
The reason for this lay partly in the decision of the Army Ground Forces command (AGF) not to act upon the growing obsolesence of the M4 design. The Sherman had performed admirably in North Africa and Italy so there was no sense of urgency to replace it. German Tigers had already been encountered by this time, but only in small number and the AGF did not expect to see them fielded in quantity.
Additionally, the AGF declined to adopt the M27 as they did not wish to interrupt M4 production, although by 1943 the manufacture of M4's had reached such a mammoth scale it seems unlikely that a staged switch over to M27 production would have significantly reduced tank output. Perhaps also of significance the M27 would have mounted the 76 mm gun, the introduction of which to the tank force was opposed by the AGF. The Ordnance Department would later suffer almost equal difficulty convincing the AGF to accept the upgunned versions of the Sherman with the net result that not a single 76 mm armed Sherman was in service in time for D-Day, even though they could have been available months earlier. The AGF's reason for rejecting the 76 mm gun was that it would encourage tank crews to stalk enemy tanks, an idea in conflict with then current US armour doctrine, and had a much less effective high explosive shell than the 75mm M3 Gun. The 76mm and 90mm guns were both accepted much more readily into the Tank Destroyer service, however US tanks would not always be able to avoid direct confrontations with German tanks and the shortcomings of the 75mm M3 gun against armour would handicap American tanks for much of the war.