There are two different types of 8x38R Tesching case types with “RP” case dimensions. T7 is the type with the shorter c11mm neck and gradual shoulder which matches the case profile of the other “RP” Tesching cartridges and is probably the true “RP” type.

T84 is the other type and has a longer neck with a sharper more distinct shoulder. Utendoerffer/RWS produced both types but only ever listed one type in their catalogues. This is a similar but not interchangeable G. Roth 8.2x37R Tesching (T49). The T7 type is the commonest type and was also listed by G. Egestorff, B. Stahl in their c1905 catalogue and subsequently by Gecado until at least 1930. The RWS factory drawing M306 seems to show this type.  It appears to have the same neck length as the 8x36R RP (T6) but with a longer case.

Early Utendoerffer catalogue drawings of the 8x38R RP seem to show a longer neck but then so do all the “RP” drawings. These are now considered to represent T7 which makes T84 a bit of a mystery. This long neck is more like the shape of the smaller calibre 7x38R La No1 (SC13). It is not just a 2mm longer neck version of the 8x36R RP (T6) as the shoulder is different – see images. It is possible that these long neck cases were produced (modified?) based on the catalogue drawing rather than the factory case drawings?

Egestorff listed their version as being Lorenz/ DWM case #93 with the same long neck and Lorenz/DWM listed case #93 (c1879) as “R.P.” showing a long neck also. However Egestorff examples show the T7 profile and Lorenz/DWM examples (which are not known to exist) would likely be T7 also.