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Feinwerkbau 127 (124) Piston Seal Replacement


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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 operate
  • Put 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 endcap
  • You 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 housing
  • I 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 progress
  • The 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 place
  • I used an abrasive cloth to clean up the residue, and polish the piston
  • It 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 compressor
  • Upon 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:

 

IMG_7023.jpg

 

Beginning of spring decompression during disassembly:

 

IMG_7024.jpg

 

More decompression (Notice the allen head wrench used to turn the spring decompressor ram)

 

IMG_7025.jpg

 

The spring is fully decompressed at this point:

 

IMG_7026.jpg

 

Here's what remains of the inside end of the original piston seal - It has a consistency a bit harder than candle wax

 

IMG_7027.jpg

 

Pieces of the old piston seal...

 

IMG_7028.jpg

 

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:

 

IMG_7030.jpg

 

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

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My first air rifle was a Benjamin model 312 in .22. Took my first jack rabbit with it at the ripe old age of 12. Still have the Benjamin, which is working fine. It was preceded by a Sears JC Higgins Daisy "cactus carbine" 700 shot BB gun, and followed by one of the first Ruger 10/22s, the early one with the cherry wood stock. Still have that one, too! And so the habit started...

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Hi Dalbert,

 

Good to hear you have the old FWB 127 back with the living. Evidently those seals are known for breaking-up. Ok. After nearly 40 years soft parts crumble. I've several FWB 124's. One from my Dad that goes back to the early 80's. All have ARH parts with lube and tar ready to go. I do have to invest in a spring compressor; been warned.

 

I envy your 127. As a youngster I wanted something to splash better shooting sticks in the pond. .177 is just a bit small for that.

 

Again, congratulations. Stay-at-home might get a few things done :)

 

Enjoy,

 

Grasshopper

 

ps. Got an R7 resting in the closet? Kind of one of the other quality guns of the era.

Edited by Grasshopper
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Grasshopper,

 

I've been looking at 124's lately. I originally wanted a 124, but the 127 was in stock at my dealer, and he was selling it cheaper than a 124 would have cost to order, so I bought it. Two of my friends had 124's, and we shot together most of the time in their yards. One of them had a pretty good range setup with a solid fence behind it, and we could sit on his lanai, and shoot from rests. I'll probably pick up a 124 here sooner or later...

 

I don't have an R7 in the closet, though my brother has an R1. I did recently acquire an FWB 600 match air rifle to be able to practice position shooting in my basement during the service rifle off-season. It's crazy accurate.

 

I hope my post helps when you get to the piston seal replacements on your 124's.

 

Thanks!

 

David Albert

dalbert@sturmgewehr.com

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I bought my first air rifle at age 70. It's a Gamo Raptor Whisper .22. I got tired of squirrels trimming their teeth by gnawing on (and through) my roof vents and I didn't think my neighbors would appreciate me using my S&W 15-22

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Great write up on the rebuild

 

Old school Feinwerkbau guns are a love of mine

Here is a FWB 150 I currently have up for sale

straight safe queen

img_0128-3-b6ff2f88-2000x497.jpg

 

It's one of the early Daisy branded guns who were the first folks to import FWB guns

note the White Line butt plate which was a unique feature seen only on the 150s Daisy contracted from FWB

Have a couple 300 Sporters as well

 

124 series rifles are one of the best designed AGs ever made

Triggers kind of suck but Maccari used to make a wonderful replacement

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Great write up on the rebuild

 

Old school Feinwerkbau guns are a love of mine

Here is a FWB 150 I currently have up for sale

straight safe queen

img_0128-3-b6ff2f88-2000x497.jpg

 

It's one of the early Daisy branded guns who were the first folks to import FWB guns

note the White Line butt plate which was a unique feature seen only on the 150s Daisy contracted from FWB

Have a couple 300 Sporters as well

 

124 series rifles are one of the best designed AGs ever made

Triggers kind of suck but Maccari used to make a wonderful replacement

 

Nice rifle. Where is it listed for sale?

 

Thanks!

 

David Albert

dalbert@sturmgewehr.com

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I advertise on the Yellow, Brads & GTA

this one's on the Yellow forum

 

Have an early 300 sporter that needs a rebuild, missing a screw too

not nearly in the 150s condition but still a decent gun

 

Have a .177 R1 rifle and a .22 R1 carbine

both real nice guns but should have a rebuild

 

wanna' Walther ?

How about a .177 LGV Especial UIT gun

those were designed to compete against the FWB 300S 10 meter rifles

another recoiless design but was quickly replaced by the single stroke pneumatic Walther LGR

 

Have a bunch of this crap

here's one you might get a charge out of:

 

img_0172-3-10885051-2000x713.jpg

 

One of my semi custom builds on a DAQ .457 big bore pistol

custom AR pattern grip frame

early Magpul ? stock on an adapter

customized forend work

 

was building all sorts of crazy at one point

 

If you are looking for something in particular PM me albert

I don't deal in Red Ryders

mostly Swede FX, old Walthers, Daystates

the nice stuff isn't cheap

 

btw, that 150 just sold a few minutes ago for my six fifty list via paypal

super clean is hard to come by and much of the AG community is cheap as heck

had some offers under $400 sigh

not going to ever happen on my watch LOL

 

best

Jim

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  • 3 weeks later...

When I was a kid there were some lively discussions about which was better, Benjamin or Sheridan, and .177 or .22. My Benjain 312 is in .22, and I contend to this day that range and hitting power were better than virtually the same rifle in .177.

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When I was a kid there were some lively discussions about which was better, Benjamin or Sheridan, and .177 or .22. My Benjain 312 is in .22, and I contend to this day that range and hitting power were better than virtually the same rifle in .177.

Sheridan was .20 cal., so a good compromise between the two. My friend had a Silver Streak, and it was a fun, well built airgun.

 

David Albert

dalbert@sturmgewehr.com

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