GTA
All Springer/NP/PCP Air Gun Discussion General => "Bob and Lloyds Workshop" => Topic started by: rsterne on February 06, 2012, 09:49:51 PM
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About a year ago I bought this 1400 as a project (like I didn't have enough already).... I'm a sucker for the wood on these early Crosmans, you never know what's hiding under there.... I've already rebuilt a few 140s, so I'm familiar with what they need and like.... When I bought this gun the Ad said "nice brown patina" and I should have known what that meant....
(http://i378.photobucket.com/albums/oo221/rsterne/Crosman%20140/Crosman1400Rust.jpg)
(http://i378.photobucket.com/albums/oo221/rsterne/Crosman%20140/Crosman1400Right.jpg)
(http://i378.photobucket.com/albums/oo221/rsterne/Crosman%20140/Crosman1400Left.jpg)
Actually the rust wasn't that bad, mostly in front of the stock where people have a tendency to pick up the gun when it's propped in a corner.... The wood is covered by Crosman's brown finish of the time but the grain underneath looks nice.... It wouldn't hold air for long and shot weakly (under 500 fps) so I pulled it apart just to diagnose it and found the quad seal leaking and replaced it.... That gave me a gun that would hold air and shoot typical of a gun of that age....320 fps at 2 pumps, 440 at 4, 510 at 6, 550 at 8, and 580 at 10 pumps.... The trigger pull was attrocious, but at least the metal trigger group on the 1400 is adjustable for pull weight where the 140 (which has the trigger mounted directly in the wood stock) was not.... I stripped the gun completely apart to start the rebuild.... Here are the parts of interest....
(http://i378.photobucket.com/albums/oo221/rsterne/Crosman%20140/Crosman1400Parts.jpg)
Starting from the top, looking at the items circled in yellow....
The cutout in the pump tube is too far forward and if you don't pump the gun VERY slowly it doesn't take in air properly as the air has to draw into the pump along the raised channel.... This is a common problem where the velocity is low unless you wait a couple seconds at the end of each "out" stroke.... The solution is to lengthen the slot and deburr it carefully....
The pump cup is difficult to replace, and this one is quite hard.... My solution is to replace the end half of the piston with a new flat topped one grooved for an O-ring.... Easily replaceable, commonly available, and you can achieve higher pressures....
The rear of the valve only has a 1/8" hole in it.... I drill it out in stages to 5/32" to match the rest of the ports in the gun....
There is an aluminum spacer in the valve which takes up about half the volume.... This means that the pressure rises very quickly, but you will notice that you get most of the performance in the first 6 pumps.... With the "dump" style valve held closed directly by the sear, the higher the pressure the harder the trigger pull.... I will be replacing the short spring and spacer with the longer one underneath them.... The additional volume will allow more velocity at higher pump numbers with reduced trigger pull weight....
The hole in the flow-through bolt is only 0.140".... I drill it out to 5/32" to match the other ports....
The stock retaining screw in this gun wasn't all mangled by pliers, so it may never have been apart.... They are usually shredded by master craftsmen, however, so I mill two flats in the larger portion to allow the use of a wrench to remove and install....
Other than these items, everything will get a thorough cleaning, rust removal, and rebluing and then I get to tackle the stock....
Bob
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Nice gun can't wait to see it complete. How hard does it shoot ?
Mike
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i thought about picking one of those 1400s up, i already own a bunch of old benji s 312s 342 , matter of fact just picked up a 342 gun is in nice shape but needs seal , how do the 1400s compare in accuracy to the benjis?
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Over the past couple of days I have been working on the modifications I wanted to do and rebluing all the metalwork.... Every single piece was cleaned, degreased (twice) and reblued with Van's Gun Blue.... There were a lot of small pieces....
(http://i378.photobucket.com/albums/oo221/rsterne/Crosman%20140/RebluedParts.jpg)
In addition I reblued the barrel, main tube, and pump linkage.... In the photo above you can see the new piston with O-ring (top right), and just below it the stock mounting bolt with the flats milled in it (hard to see).... Once everything was finished and oiled lightly I reassembled the gun and ran a few pellets through it....
(http://i378.photobucket.com/albums/oo221/rsterne/Crosman%20140/Crosman1400Reblued.jpg)
If you compare the photo above to the first one in this thread, you can see the improvement.... I was quite pleased with the increase in performance as well.... 2 pumps gave 305 fps, 4 gave 442, 6 was 534, 8 was 588, and 10 pumps was 620 fps.... The gun now shoots harder at 8 pumps than it did originally at 10 pumps.... and the trigger pull is much lighter as well.... I'm quite pleased with the results.... Now to get on with refinishing the stock....
Bob
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I got the old brown finish stripped off the stock today.... Pretty nice grain hiding under there....
(http://i378.photobucket.com/albums/oo221/rsterne/Crosman%20140/StrippedStock.jpg)
Staining and sanding tomorrow, hopefully....
Bob
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Here is a photo with the Dark Walnut stain done....
(http://i378.photobucket.com/albums/oo221/rsterne/Crosman%20140/1400StockStained.jpg)
If anything, the contrast will increase with the Watco Oil Finish when I rub it out....
Bob
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That stock looks great very nice job.
Mike
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looks swet, picked up a blue streak myself today at a yard sale , found it its what they call a flat top from the 50s , definitley will restore it , its not in bad shape good luck with restoration
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The restoration of this Crosman 1400 is completed.... The stock received seven coats of Watco Dark Walnut Danish Oil, each coat wet sanded ending with 600 grit.... It was then waxed with Dark MinWax, three coats.... which resulted in an incredibly smooth finish with a medium gloss.... Here is the results....
(http://i378.photobucket.com/albums/oo221/rsterne/Crosman%20140/1400RestoredRight.jpg)
(http://i378.photobucket.com/albums/oo221/rsterne/Crosman%20140/1400RestoredLeft.jpg)
In addition to the rebluing, detailed above, the ports have all been brought up to at least 5/32" and the resulting velocities are 515 at 5 pumps, 610 at 8 pumps, and 660 at 10 pumps.... The trigger pull is much lighter than it was to start with, although it is very long.... I'm extremely pleased with the way it turned out.... especially when you see what I started with in the first post.... ;D
Bob
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very very nice , refinishing a stock on a benji 342 , was going to use true oil , but may do what you did thx
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Looks like a very nice rifle. Have fun with her.
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SA-WEET!
I would love to own that!
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Very nice! I also have the want to redo a 1400 also....
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SA-WEET!
I would love to own that!
Thank you Bob!
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I hope you enjoy it !!!
Bob
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;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D !
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rsterne - your attention to detail is most noticeable. The rifle is sure to be an heirloom. Take good care of it!
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rsterne - your attention to detail is most noticeable. The rifle is sure to be an heirloom. Take good care of it!
I will! :D