It sounds like your sling is still just in premolt. An easy way to tell is if its abdomen is darkening. When the tips of its legs goes black, the molt is just a day or two away. When it molts, it should be all over in a hour or two. The bigger they get, the longer it takes.
PS: Don't be alarmed when you find him on his back one day! He is just molting! Don't touch or disturb!
Ts:
0.2.0 B. Vagans (13cm)
1.0.0 L. Parahybana (16cm)
0.1.0 N. Chromatus (13cm)
1.0.0 A. Versicolor (11cm MM)
1.0.0 P. Faciata (17cm)
1.0.0 P. Regalis (16cm MM)
1.0.0 B. Boehmei (4cm)
0.0.1 B. Albopilosum (6cm)
0.0.1 B. Smithi (4cm)
0.0.1 B. Auratum (4cm)
0.0.1 P. Irminia (6cm)
0.0.1 A....