Airgunsmith Benjamin 392/397 Trigger Mods
 


Crosman Benjamin has built in my opinion one of the safest airguns on the market do to the healthy torsion spring and sear angle contact with the striker,  my advice is not to mess with the torsion spring 397-052 and the sear striker contact points (sear lock) if you do adjust or change the sear angle or lighten the torsion spring the gun must be rigorously tested "UNLOADED" as to its safeness,,,,, a lighter torsion spring can be made with hardened wire that has been straightened  or can be found at your local fishing supply house, the sear and striker can be lightly ground to slide instead of bind when you pull the trigger,, “”A BAD combination is to lighten the torsion spring and change the sear angle”” when you squeeze the trigger on the Benjamin 392 / 397 the trigger rocks the sear in a downward motion ( horizontal angles move down—vertical angles move back), its this backward motion that give you most of you trigger resistance buy pushing the striker back into an already compressed 2200A32 striker spring, if you eliminate the backwards push you will receive much less trigger resistance.  Before you do any of the above mentioned  try grinding a dip in the sear, if you grind it so the sear is in contact with the trigger and the  tip of the trigger has a 1/32 gap between the trigger and sear you will have a trigger pull that’s as smooth as silk and crisp as lighting, grind the dip a bit deeper you will have what feels like a 2 stage trigger

The diagram you see on the left shows the 4 points to a Benjamin 392 / 397 trigger tune, arrow 1 works in combination with arrow 2 sear spring 766.091 with out this spring the bolt safety will not disengage (you will not be able to cock the bolt) The problem with this spring is it adds 1 to 2 pounds of trigger pull. The best way to approach this extra trigger pull is to replace with a lighter spring.
The Crosman / Benjamin 392/397 sear looks to be stamp out of steel as in the next photo you will see where the steel was squeezed together and then snapped leaving a ridge. The finger on the left is what were concerned with, this will need to be cleaned up in order to achieve the smoothest possible action
This is the ridge that needs to be cleaned, this can be done with a Dremel tool or a knife stone, great improvements can be accomplished here with a good flat and polished surface. But if we take this one step farther we can reshape the sear with a dip or a down ward slope.
This is the same sear that has been ground to include a dip where the trigger and sear contact each other, when done in this manner the trigger is not sliding on flat surface but rocking from the top of the dip to the bottom
Here you can see the dip. Grind it deep enough so the heal of the sear (arrow) is in contact with the trigger this allows the trigger to rock inside of the dip

Do not grind on the tip where the red arrow is pointing

This is the mating surfaces of the Benjamin trigger and sear, If done correctly you will find this is as good as it gets,

You can experiment with the depth of the dip, deeper will allow more rocking and a softer pull.

Here's the completed trigger tune with ground & polished sear and after market sear spring 766.091. Don't for get to lube every metal to metal contact this includes the spring contacts
If you would like an even lighter pull you can replace the sear spring part number 397-052 with a lighter spring, we have done this but here's your caution,,, with a lighter spring bumping and or dropping a Benjamin 392 / 397 with a lighter sear spring that replaces spring 397-052 will cause this gun to fire, We suggest this only be done to guns used for target shooting, ((NOTE)) there are 2 sear springs the 397-052 & 766.091, the spring we have replaced in this tune is the 766.091 with part #C-660 see next photo, this spring can be replaced without degrading the
Benjamin 392 / 397 safety

 

After market spring c-660 ( hardware store)
Taking it one step further slotting and installing a bearing to the mating surface removing almost all friction

Copyright © 2005 airgunsmith .com All rights reserved.