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Astra 900 Disassembly
The 900 looks much like the C-96 on the outside, but the inside is entirely different. All those pins the C-96 doesn't have are in the 900, with some to spare. You really can't go very far with a field strip of the Astra - it's all detail strip.
Although on the right side of the frame all the pins seem to be hanging out in the air, the interesting design feature is that all of them have heads on their left ends, so that they can only be pushed out from right to left. But only one pin is visible on the left side of the frame - the others are all under the sideplate. So the sideplate is both a cover for the mechanism and a retainer for the pins. That means that the pins don't have to be tight fits just so that they don't fall out of the gun. You don't need a hammer, punches or drifts to disassemble an Astra 900. If you think you have to hammer a pin out, you are probably doing something wrong - stop and investigate before you bust something. Replacement parts are simply not available for these guns, although a few Mauser parts will fit.
There are only two pins on the gun which are removed with a hammer and punch. The obvious one is the small one to the left -
It releases the larger pin at right (which doesn't have to be hammered out), which in turn releases the bolt lock. You don't need to touch either for routine disassembly. The other pin which needs a punch and hammer is internal - it attaches the hammer to the hammer strut. You don't need to touch that one either to take the gun apart.
Although not needed, a couple of pin punches are useful, but they need not be heavy-duty - the ends of heavy paper clips should do. A flat-bladed screwdriver is needed to remove the firing pin and the grip screw. A tap from the screwdriver might be handy when removing the sideplate.
The gun shown in the photos is an early 900, dated 1928. It has the earlier small ring hammer, the later large-size grip, but not the later 12-groove grip panels. But no matter, the internal parts and the stripdown procedure didn't change throughout the 900's production lifetime. The sideplate shown is a mismatch - it's the correct 1-line "address" plate, but from a different (and obviously badly corroded) gun.
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Detail strip
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Verify that the gun is unloaded.
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The floorplate, cartridge follower, and magazine spring are nearly identical to those of the C-96. Replacement Mauser magazine springs will fit the Astra just fine.
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All the pins, round or square, will be pushed out from the right to the left.
The four pins in a cluster at left are, from left, the hammer pin, the hammer spring stop pin, the sear spring pin, and the sear pin. The square pin at top is the sidecover pin. The round pin next to it is not removed during routine disassembly. That one's a job for fancy tools with a gunsmith attached to them. It holds in the cam which lowers the bolt lock after the barrel assembly has recoiled a bit, in turn unlocking the bolt and knocking the disconnector out of engagement with the sear. The next square pin is the barrel pin. The round pin beyond it is the trigger pin. The round pin 'way up forward is the floorplate latch pin.
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Push the safety lever up until it lines up with the scribe mark in the sideplate. In this position, the safety lever unlocks the sidecover pin (the big square one).
[Oh, so that's what that mark is!]
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Push the sidecover pin from the right side toward the left. The pin should not be tight - if it puts up a fight, try pushing the barrel back a few thousandths of an inch. If that doesn't work (though it usually does), wriggle the safety lever up and down a bit. Don't hammer on the end of the pin, as you'll just bend the sidecover.
The hammer can be cocked or not; it doesn't matter at this point.
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Pull the pin out.
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Slide the side cover aft. It should be no more than finger tight, but if it hasn't been moved in thirty years it may need a tap with a drift in the fingernail cutout near the back edge. A flat screwdriver makes a good drift in this application. If the finish on the gun is any good use a piece of wood instead of the screwdriver.
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At last, the mysteries revealed. Pull the safety lever all the way back, as shown, and lift off. If it puts up a fight, wait until you have the barrel assembly off; then it should be easier.
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Push out the barrel pin - the other square pin - from the right, and pull it out to the left. You will probably have to push the barrel back a few thousandths of an inch to get it to clear the pin. Here we are, with the pin removed - it came out of that horseshoe-shaped hole.
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The barrel assembly lifts off, straight up - it doesn't have to be slid along rails like the C-96. Watch for that spring in front.
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The firing pin, bolt stop, bolt, and recoil spring are removed exactly as they are on the C-96. To remove the bolt lock, its pivot pin has to come out. And to do that a small retaining pin has to be driven out with a hammer and punch - I've never bothered. A C-96 replacement recoil spring fits and works fine in the 900. The sight disassembles just like the Mauser version.
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The big pin just above the grip is the hammer spring stop pin. It doesn't seem to do much, except prevent the hammer spring from flying across the room when the hammer is removed. As we're removing everything, push/pull that pin out now - no need for concern, nothing will fly out at this stage.
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Take out the grip screw and remove the grip panels. Pull the hammer all the way back, past the full cock position, and stick a small pin punch in the hole, as shown. An end of a heavy paper clip will do if small pin punches are in short supply.
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The hammer pin can now be pushed/pulled out. Keep the pin punch in the hole. This is a procedure where three hands would be convenient.
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The hammer and pin, removed. The strut is attached to the hammer with another pin which I've never bothered to remove.
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Point the upper part of the gun someplace safe - not toward your face, the TV, or the cat - and pull out the pin punch. The hammer spring and plunger will shoot out.
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Push/pull out the sear pivot pin. Tilt the gun so that the sear falls out the back of the frame.
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Pull out the disconnector pin. Push the disconnector off the trigger spring, and tilt the gun over so the disconnector falls out the back of the frame.
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Push/pull out the trigger pin, and maneuver the trigger out the top of the frame.
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Here is the sear spring. Push/pull the sear spring pin out, and tip the gun so the sear spring falls out the back of the frame.
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Here, the trigger, disconnector, sear, hammer, strut, plunger, and hammer spring are shown in their correct operating positions, with their pins. The sear spring is in its approximate position.
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The floorplate latch and its spring are retained by a pin which is at a strange angle. Use a pin punch to tap the pin out from the right side of the gun to the left.
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Pull out the pin.
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Pull out the floorplate latch, and tap its spring out of the frame.
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Reassembly
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Reassemble in reverse order. Watch the orientation of the floorplate latch - the cutout portion must clear its retaining pin. Look down the retaining pin hole and rotate the latch until the hole is clear.
Put in the sear spring and sear spring pin.
Push the trigger in through the top of the frame, and the disconnector from the back. Put in the disconnector pin, so that the disconnector and trigger are connected. Then push the trigger spring around until it falls into the hole in the bottom of the disconnector. Put the trigger pin in place.
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Put in the sear and sear pin. Then pivot the top of the sear back and down. This is only possible because the hammer isn't in yet. The sear spring can now be pushed up and back. Do that with a flat-blade screwdriver - push it up further than the picture shows.
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Pivot the top of the sear forward, and fiddle with the disconnector until it catches the bottom of the sear, as shown. This will keep the sear spring in place while we reinstall the hammer.
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Put the plunger in the hammer spring, and stuff the spring down its hole. Compress with a pin punch. Use the small pin punch in the hole in the frame to hold the hammer spring and plunger in place. This is another three-hand operation.
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Position the hammer and strut.
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Maneuver the hammer into position, with the strut resting on top of the plunger. Push in the hammer pin. You will probably have to work the trigger a bit to get the sear to clear the hammer. With the hammer in approximately its correct position, the sear won't be able to move far enough to release the sear spring. And a damn good thing, too.
Pull out the small pin punch, releasing the hammer spring.
Put the large hammer spring retaining pin in place.
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Orient the gun vertically, as shown, and put the barrel spring in its hole in the frame.
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Put the barrel assembly in place. The vertical orientation keeps both the spring and the bolt lock in their places until the barrel assembly is positioned on the frame. This step can be done horizontally, but that's another three-hand job.
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Push in the barrel-retaining pin. Install the safety lever.
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Push the safety lever up and forward. Slide on the sideplate. Align the safety lever with that alignment mark on the sideplate. Push in the sideplate pin (as usual, from left to right).
Put on the grip panels. Give the bolt, hammer, trigger, and safety a workout, to see that all are working right.
Put in the cartridge follower, magazine spring, and floorplate.
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