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Hey all. Thanks for having this place. This thread is one of the best resources Google has found for me in hunting down information regarding my newly-acquired Unique D4. Mine's serial number 5274(xx) and in slightly rough shape in terms of finish, but mechanically nearly perfect. I've taken it down and cleaned and lubed everything, smoothed a few manufacturer-sharp corners and edges which were close to 'ouch' sharp (magazine edges top and bottom, a couple of switches on the pistol, compensator slot edges, etc) and the biggest problem with this one on initial inspection was that the bottom-rear of the compensator was slightly proud of the barrel crown. !!!
My initial thought was wow, that's some really bad manufacturing. But further inspection showed it to be lead and powder residues piled up, filling most of the muzzle brake including well up into the slots, though they were still about 60% open. So I chipped away from the slots, and while cleaning those realised that each one was cracked, the deepest cracks below the rear-most slot then progressively less so. Apparently the leading had been there for some considerably long time while the pistol was still being shot a lot, bullets were hitting the lead on the bottom face, tumbling, and striking the slots, cracking the steel. Hard to imagine gas pressure causing that kind of damage without help from some metal-on-metal contact. Since the compensator bore is about 0.27 and the hole inside a lot bigger, cleaning from the front wasn't going to work. So I set myself the chore of getting the thing off the barrel, without knowing how it was attached. Guessing threaded, I clamped the barrel into a custom walnut clamp with rosin packed into the hole and padded a long wrench and tested it with conventional right-handed thread (turning counter-clockwise) technique. It turned, very reluctantly. Gradually it eased up until after about 2 turns it was moving quite a bit more freely. Continually checking the barrel/brake join I saw that it wasn't changing. No threads. So this was a hot-fit, apparently with something like Loctite, and the heat generated by turning it (thing was getting uncomfortably hot just turning it with a wrench) loosened it still further until I was able to encourage it forward and off the barrel. Sure enough, some sort of brittle residue between the parts. Being 1950's manufacture I'd guess not Loctite, but something anyway. Cleaned of this gunk it's a fairly easy fit with the parts at room temperature, not sloppy at all.
Since the condition doesn't exactly cry out 'this is a collector's piece!' I decided to go ahead and bore from below the rear end of the brake for a small set screw to retain it instead of gluing it on after the cleaning. Works neatly, engaging with a shallow filed slot for alignment of the front sight, and doesn't show unless one looks underneath.
Cleaning out the lead was less simple. I poked at it, but no real progress made. So I started drilling, using larger and larger drills until barely scraping steel. Same bore as the stepped barrel nose all the way to about 5/8" from the brake muzzle. Now clean as a whistle, polished out with 400 grit paper on a dowel.
Next up was the barrel crown. Chopped off square but not very neatly, filthy, it did not look good at all for accuracy. So I re-crowned to a shallow spherical face, polishing with lapping compound until it looked reasonable. Lots of other little touch-ups here and there. And the grip this one came with was a custom walnut monstrosity drastically over-sized, in two parts which wobbled badly. But nice walnut. So I cleaned the meeting face, epoxied them together and proceeded with carving to make it fit my hand nicely. Finished with Lee Valley's classic linseed oil varnish, and will probably rub in a couple more thin coats over time.
I have tried one shot. Cycled perfectly with Remington Subsonic. Loud. Almost no recoil, about like shooting a higher power .22" PCP air pistol. Very nice. I'm going to enjoy this pistol very much. Wouldn't mind picking up an extra mag or two sometime, though it came with two and with some cleaning and smoothing they plug in very easily and work perfectly. Quite a few differences between them. I'm curious if anyone knows which might be original and which from an earlier/later model or after-market? Perhaps neither is original? Anyway, springs are in perfect shape, all important metal bits close to new with the worst wear having come from grip mounting screws being too far into the frame so they were scoring the sides badly. Got that all sorted so the magazines slip in and out with no screw contact, very slick. The slight rearward pressure on the catch needed for loading is easy enough once practised a few times.
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Oh, and a couple of other notes on the D4. The barrel has been said in a few places (such as the original French documentation shown on various websites) to be 217mm long. Not this example anyway. This barrel is 186mm long, and adding the larger-bored compensator which doesn't count as barrel it's 230mm, so no 217mm to be found here. Guess they made different-length models?
And I forgot to post a picture of the barrel before and after re-crowning. Well, after on the left, before on the right. The rifling is 6 shallow grooves, fairly wide, and appears clean and sharp throughout the length of the bore.
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And I neglected to mention specific diameter for the brake step cut onto the barrel, should that be of interest to anyone. It's 0.435" diameter or 11mm, and 0.70" or about 18mm long, stepping down from the 0.50" barrel.
Ah, found yet another thing to make it worth editing this first post of mine here. A discovery! I was wondering about elevation adjustment, since the rear sight blade is windage-only and the front sight looked very simple and rather low. But then looking more closely at the front sight blade just now I thought hey, that slot looks like it might be deeper than it needs to be for such a small blade... I wondered if it was reversible, a two-height blade? So I loosened the screw, which turned out to be a short grub screw with the blade held by a pin in front. And the blade rotated freely! It's adjustable for elevation, swinging down to a level surface about 0.8mm above the brake and up as high as 5.5mm above. There's a deeply scribed line on the left hand side, seemingly the default elevation mark, at 3.5mm tall. Cool. I've never seen a vertically adjustable front sight before, at least not on a pistol.
My initial thought was wow, that's some really bad manufacturing. But further inspection showed it to be lead and powder residues piled up, filling most of the muzzle brake including well up into the slots, though they were still about 60% open. So I chipped away from the slots, and while cleaning those realised that each one was cracked, the deepest cracks below the rear-most slot then progressively less so. Apparently the leading had been there for some considerably long time while the pistol was still being shot a lot, bullets were hitting the lead on the bottom face, tumbling, and striking the slots, cracking the steel. Hard to imagine gas pressure causing that kind of damage without help from some metal-on-metal contact. Since the compensator bore is about 0.27 and the hole inside a lot bigger, cleaning from the front wasn't going to work. So I set myself the chore of getting the thing off the barrel, without knowing how it was attached. Guessing threaded, I clamped the barrel into a custom walnut clamp with rosin packed into the hole and padded a long wrench and tested it with conventional right-handed thread (turning counter-clockwise) technique. It turned, very reluctantly. Gradually it eased up until after about 2 turns it was moving quite a bit more freely. Continually checking the barrel/brake join I saw that it wasn't changing. No threads. So this was a hot-fit, apparently with something like Loctite, and the heat generated by turning it (thing was getting uncomfortably hot just turning it with a wrench) loosened it still further until I was able to encourage it forward and off the barrel. Sure enough, some sort of brittle residue between the parts. Being 1950's manufacture I'd guess not Loctite, but something anyway. Cleaned of this gunk it's a fairly easy fit with the parts at room temperature, not sloppy at all.
Since the condition doesn't exactly cry out 'this is a collector's piece!' I decided to go ahead and bore from below the rear end of the brake for a small set screw to retain it instead of gluing it on after the cleaning. Works neatly, engaging with a shallow filed slot for alignment of the front sight, and doesn't show unless one looks underneath.
Cleaning out the lead was less simple. I poked at it, but no real progress made. So I started drilling, using larger and larger drills until barely scraping steel. Same bore as the stepped barrel nose all the way to about 5/8" from the brake muzzle. Now clean as a whistle, polished out with 400 grit paper on a dowel.
Next up was the barrel crown. Chopped off square but not very neatly, filthy, it did not look good at all for accuracy. So I re-crowned to a shallow spherical face, polishing with lapping compound until it looked reasonable. Lots of other little touch-ups here and there. And the grip this one came with was a custom walnut monstrosity drastically over-sized, in two parts which wobbled badly. But nice walnut. So I cleaned the meeting face, epoxied them together and proceeded with carving to make it fit my hand nicely. Finished with Lee Valley's classic linseed oil varnish, and will probably rub in a couple more thin coats over time.
I have tried one shot. Cycled perfectly with Remington Subsonic. Loud. Almost no recoil, about like shooting a higher power .22" PCP air pistol. Very nice. I'm going to enjoy this pistol very much. Wouldn't mind picking up an extra mag or two sometime, though it came with two and with some cleaning and smoothing they plug in very easily and work perfectly. Quite a few differences between them. I'm curious if anyone knows which might be original and which from an earlier/later model or after-market? Perhaps neither is original? Anyway, springs are in perfect shape, all important metal bits close to new with the worst wear having come from grip mounting screws being too far into the frame so they were scoring the sides badly. Got that all sorted so the magazines slip in and out with no screw contact, very slick. The slight rearward pressure on the catch needed for loading is easy enough once practised a few times.
Oh, and a couple of other notes on the D4. The barrel has been said in a few places (such as the original French documentation shown on various websites) to be 217mm long. Not this example anyway. This barrel is 186mm long, and adding the larger-bored compensator which doesn't count as barrel it's 230mm, so no 217mm to be found here. Guess they made different-length models?
And I forgot to post a picture of the barrel before and after re-crowning. Well, after on the left, before on the right. The rifling is 6 shallow grooves, fairly wide, and appears clean and sharp throughout the length of the bore.
And I neglected to mention specific diameter for the brake step cut onto the barrel, should that be of interest to anyone. It's 0.435" diameter or 11mm, and 0.70" or about 18mm long, stepping down from the 0.50" barrel.
Ah, found yet another thing to make it worth editing this first post of mine here. A discovery! I was wondering about elevation adjustment, since the rear sight blade is windage-only and the front sight looked very simple and rather low. But then looking more closely at the front sight blade just now I thought hey, that slot looks like it might be deeper than it needs to be for such a small blade... I wondered if it was reversible, a two-height blade? So I loosened the screw, which turned out to be a short grub screw with the blade held by a pin in front. And the blade rotated freely! It's adjustable for elevation, swinging down to a level surface about 0.8mm above the brake and up as high as 5.5mm above. There's a deeply scribed line on the left hand side, seemingly the default elevation mark, at 3.5mm tall. Cool. I've never seen a vertically adjustable front sight before, at least not on a pistol.
