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In Hawaii in 1981, when I was 15 years old, I was heavily into airguns. At that time, I saved up and bought a new Feinwerkbau 127 .22 caliber air rifle. I still have the receipts for it, and all the accessories I bought for it. It was my favorite possession for the next 3 years, until I turned 18, and could purchase firearms. It still holds a very special place in my heart. If you are, or are not familiar with the FWB 124/127 series, they are now considered classic spring piston air rifles, highly sought after by airgunners today. The 124 model is the .177 caliber version, and the 127 is the .22. Around 20 to 25 years ago, the piston seal failed on the rifle, and it would no longer shoot. I had not fired it since then...until Sunday, when my favorite air rifle finally came back to life! I just want to document a few things that could help others who may find this post through a web search. I purchased an Air Venturi Rail Lock Airgun Spring Compressor for $95 from Pyramid Air to accomplish the repair. There is no way to replace the piston seal without a spring compressor, and it would be quite dangerous to attempt it without an appropriate tool. Many folks have fashioned tools of various types to compress/decompress the powerful mainspring, and I had originally intended to follow that same path when I saw the Air Venturi product, which utilizes a unique method. It attaches to the Weaver rail on the rifle, and uses it as a base to hold a spring compressor in place behind the mainspring housing, allowing the mainspring to either decompress, or compress slowly, enabling the safe removal of the mainspring and associated internal parts. I also purchased a replacement piston seal, chamber seal, and two types of airgun grease from Air Rifle Headquarters. The airgun grease I purchased was heavy tar, and super moly paste. I coated the piston and piston seal, as well as the endcap parts with the super moly paste, and coated the outer edges of the mainspring with heavy tar. Here are the key hints I'll provide to others who may want to attempt this type of repair. When you start, make sure you install the spring compressor as far back on the Weaver rail as possible, to give yourself the most room for the threaded compressor rod to operatePut pressure on the endcap with the spring compressor before you remove the large bolt that holds the mainspring and endcap in place (It's the large, round bolt that another bolt threads into from the front of the trigger guard to hold the action in the stock)Go slow on disassembly and assembly - Make sure the plastic end of the ram stays engaged firmly in a good spot on the endcapYou will need to unscrew the barrel extension from the mainspring housing to be able to fully disengage the lever from the cocking nub that moves along the underside of the inside of the receiver (I don't know the official name) - After reassembling the mainspring, the cocking nub may be rocked into place through the rectangular opening in the bottom of the mainspring housingI spent about 2 hours with a very long screwdriver scraping the old piston seal from the end of the piston chamber - Keep going until it is clean - You'll need a small flashlight to see your progressThe leftover piece of piston seal in the end of the piston can be carved out with a screwdriver, and I also used a seal puller tool to get the inside area where the new piston seal will engage and lock in placeI used an abrasive cloth to clean up the residue, and polish the pistonIt will be more difficult to get the endcap re-engaged on the plastic end of the spring compressor ram during re-assembly - This is because you will be pushing the piston with the new piston seal installed all the way forward - Be careful that you don't launch the endcap across the room while getting it mounted in the compressorUpon reassembly, I used a cable tie to keep the safety and safety spring in place on the endcap until they progressed well into the mainspring housing, and then I cut off the cable tie Here are several photos. I did not take photos of the re-assembly because my hands were filthy from applying the two types of lubricants. Rifle action with spring compressor installed: Beginning of spring decompression during disassembly: More decompression (Notice the allen head wrench used to turn the spring decompressor ram) The spring is fully decompressed at this point: Here's what remains of the inside end of the original piston seal - It has a consistency a bit harder than candle wax Pieces of the old piston seal... The screwdriver I used to reach the end of the inside of the mainspring housing to scrape away the remains of the front end of the original piston seal: Again, I'm posting this in the hope that it will help someone in the future. If anyone else on this board has an FWB 124 or 127, then feel free to do an airgun geek post here to tell everyone what wonderful air rifles these were in their day, and still are today. This old airgun has new life! Cheers! David Albert dalbert@sturmgewehr.com