[somd_mustangs]

Nick, Good catch on that being a fairly rare Fabrique Nationale frame!
OP, that looks like a really nice example.

I would be very gentle cleaning the frame, that plum finish is fragile. If it still has strong finish on the front of the grip frame that is unusual and worth carefully preserving I don't have any solid statistics but I've seen, handled, or owned several of these H block AC44 E/140 frames that had the Otto Single Type I grips So I'd consider them A-OK for that gun.
Maybe two brothers, or his and hers initials?

I would not use Hoppe's on the frame in particular, just the Ballistol and a soft cloth (personally I like the G96 gun treatment CLP but Ballistol is good stuff).


^^ As an aside, someone on another forum had an issue with Hoppe's destroying the blued finish on a 3rd gen Colt after inadvertently leaving it soak for several weeks... granted that isn't a good thing regardless The Hoppe's representative told him in no uncertain terms it's only meant as a bore cleaner, not for use on bluing. That was a new one on me! I think the formula has changed significantly over the years... "not my Grandfather's Hoppe's" LOL. I left an early Zero series slide in a Hoppe's bath for an hour or so and it clouded the finish, but I can't "prove" it was caused by the Hoppe's. So I steer away from it now other than quick wipe of internal parts or cleaning bores. No more soaking... nor leaving it on a surface... just to be on the safe side. Your mileage may vary...

 

[somd_mustangs]

No worries, I didn't take your comments to be argumentative at all, just informative. My own personal experience is that the Hoppe's did seem to affect the high-polish finish and it did not make me happy. But as I said, "your mileage may vary" LOL.

I do like your pistol. The ones I've run across are almost always worn on the grip strap. I have a special affinity to P.38's with FN parts for some reason.

Anyway, for these WW2 Walthers with plum-finish frames, I wouldn't put anything on them except oil. It's a very thin finish and not the typical bluing, it didn't penetrate very well. Maybe wiping with Hoppe's or other solvents won't hurt it, but... why chance it. That finish is an acquired taste, I originally thought it was just a sign of a poor bluing job, but in context it's pretty interesting and makes for a nice contrast.

Gratuitous pic of one of my favorites that changed my mind about it, a mint late-war Mod P38 - many in this S/N range are plum to some extent. Poor temperature control, incorrect solution mix, etc. It's REALLY plum, the pic doesn't do it justice. The slide is like flip-flop paint, it changes color depending on lighting and view angle.