[George Hopp]

My dear Herr Prien,
Having enjoyed your superb books for many years, it is an honor to try to be of some small help to you in the matter of the 109G-6/U4.

I have a copy of the Tarnewitz report for 21.7.43 with the title "Einbau und Funktionsüberprüfung der MK 108 in den ersten 30 Flugzeugen Bf 109 G6/U4" (Installation and functional testing of the MK 108 in the first 30 Bf 109 G6/U4s). I had hoped to post the report, but some of the words are difficult to make out, so I will, in the interests of time, just give you the gist of the report: The task was originally to simply install the MK 108s in the a/c, and then to give them a short functional test.

The implementation of this simple plan would consist of the following: The a/c were accepted minus the weapons, which I assume meant only the MK 108, rather than also the MG 131s. The weapons came from the final production line at DWM-Posen. The associated units for remote firing of the weapon came from Rheinmetall-Borsig, Berlin-Tagel and its sub-contractors. Anticipated was a short firing of the weapon on the firing stand, then a short firing of the installed weapon on the ground, and finally a short firing of the installed weapon in the air. But, in the rush to make the MK 108 operational it had not undergone the complete testing as specified by GL/C-E6.

Results: The 9 MK 108s delivered at the end of May had so many problems on the firing stand that installing them in a/c was out of the question. In mid-June, 24 improved MK 108s were delivered. They worked well enough that one was installed in an a/c for testing. But, there were numerous problems with the installation that required extensive firing on the firing stand. The report then listed 8 major problems encountered. It also mentions that the training ammunition supplied by DWM had a different fuse cap than the Rheinemetall training ammunition with the result that 3 cannon were destroyed by the exploding cartridge casings.

In the end, everything was fixed up; and at the date of the report (21 Jul 43), of the original 30 a/c, 10 were still at Tarnewitz, and the others had been sent on to Schwerin or to Lärz.

So, according to the wording of the report, it would appear that the 30 a/c mentioned were, in fact, accepted by Tarnewitz as genuine production G6/U4s rather than any other modified a/c. The factory of origin of these a/c is never mentioned, nor were any a/c W.Nrs.

I hope this helps,
George Hopp