In this note we consider Coulomb-branch chiral primary correlation functions in N = 2 superconformal QCD with gauge group SU (2), in the limit of large R-charge J = 2n for the chiral primary operators [O(x)] n with the inverse gauge coupling τ held fixed. In previous work [5][6][7][8] these correlation functions were determined to all orders in n, up to unknown exponentially small corrections. In this paper we determine the first several orders of the asymptotic expansion of the exponentially small correction itself. To do this we use: the physical interpretation of the exponentially small correction as the virtual propagation of a massive BPS particle, to fix the leading term in the expansion; the supersymmetric recursion relations of [3,14,67,68] to derive differential equations for the coupling-dependence of the subleading terms; and the double-scaling limit of [9,13], to fix undetermined coefficients in the solution of the differential equation. We calculate the expansion of the exponentially small term up to and including relative order n − 5 2 . We also use the recursion relations to calculate the subleading large-J corrections to the exponentially small correction in the double-scaling limit, up to and including relative order n −5 at fixed double-scaled coupling λ. We compare the expansion to exact results from supersymmetric localization [91] at the coupling τ = 25 π i, up to n = 150. At values n ∼ 100 − 150, we find the fixed-coupling and double-scaled large-R-charge expansions are accurate to within one part in 10 6 and 10 8 , respectively, of the size of the exponentially small correction itself. Relative to the full correlator including the dominant eft contribution, these estimates give results accurate to one part in 10 15 and 10 17 , respectively.