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PostPosted: Sat Jan 09, 2016 9:04 pm 
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Joined: Thu Oct 08, 2015 6:35 pm
Posts: 87
In previous posts, I documented my experiments with converting a stock 2240 to .177, using the barrel from my 1377 pumper.

Unfortunately, as expected it shot too hot, because of the .22 power plant driving .177 pellets through a longer barrel.

I swapped in a Mountain Air velocity adjuster, so that I could experiment with hammer preload. Since I was throwing money at the conversion anyway, I also added a nicely prepared, recrowned barrel and a long-probe bolt from Mountain Air.

The adjuster worked very well, allowing me to reduce the velocity at will, even with the stock hammer spring. However, I ran into other issues:
    The MA adjuster has a built-in spring guide, and the too-long bottom Crosman screw was trapping the hammer spring against the guide, galling it.
    The velocity spread was much higher.
    The pistol was still wasting gas, and louder than I wanted.
    At sub-PAL velocities with the stock hammer spring, the adjuster screw had to be out 5 turns out from flush.

Based on excellent advice from other members, I decided to go beyond simply clipping the hammer spring, and spent a couple of hours lightening the hammer as well.

After fiddling with the setup to accommodate the lighter hammer, I was able to determine the correct hammer spring length to work with the stock end-cap, ensuring that my pistol would consistently stay sub-PAL.

Walla: a quiet, stock-looking .177 caliber 2240 with a 10.5" barrel that shoots nice, tight groups, sips C02, and consistently sends a variety of 7.9gr pellets downrange at velocities in the mid-480's.

I am a happy camper.


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PostPosted: Sun Jan 10, 2016 5:57 am 
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Joined: Sun Jan 09, 2011 8:07 am
Posts: 3320
Location: Central West River Nova Scotia
congratulations !

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If I had only one wish, it would be to be able to "unsay" things.


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PostPosted: Sun Jan 10, 2016 1:28 pm 
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Joined: Tue Oct 13, 2009 1:27 am
Posts: 2514
Location: Vancouver
Ha, I beat Rick to the punch on this one.... PICS OR IT DIDN'T HAPPEN!


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PostPosted: Mon Jan 11, 2016 1:29 am 
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Joined: Thu Nov 02, 2006 4:57 pm
Posts: 1754
Location: mb
BassmanSteve wrote:
After fiddling with the setup to accommodate the lighter hammer, I was able to determine the correct hammer spring length to work with the stock end-cap, ensuring that my pistol would consistently stay sub-PAL.

Walla: a quiet, stock-looking .177 caliber 2240 with a 10.5" barrel that shoots nice, tight groups, sips C02, and consistently sends a variety of 7.9gr pellets downrange at velocities in the mid-480's.

I am a happy camper.

Congrats! It's a fair bit of trial, error, and turd polishing, but in the end it can be really worth it. I really like mine too. . . .

You can now refer to it as "your 1740", and "we" will know of which gun you speak. . .

Lucky buggers in the US, can apparently still order 1740 roll stamped main tubes, from Crosman Corp. . .

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Don't Be Sexist - Broads Hate That.


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PostPosted: Mon Mar 21, 2016 5:41 pm 
Sweet the person I was trying to get a hold of.

I just completed this mod, waiting on the chrony so I can play spring switcherooo, I have a 2300 style RVA installed. I was worried I needed to cut the barrel.


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