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Thread: Crosman 2240, 1377 trigger modification

  1. #1

    Crosman 2240, 1377 trigger modification

    Crosman 2240/1377 trigger modification

    This gets a bit tricky because there have been three different triggers and three different pistol grip frames used in just the models above and more variations on the variants. I will do my best to separate out the modification aspects for the brass triggers (1300A007) and the “custom shop” triggers (1300-017?) and the early 2 screw frames (1322A051) and the later 3 screw frames (1322-051?).

    The brass triggers (1996 to 2009) are brass (duh) and are narrower in the face than the black painted triggers that come on the later models(2010 to present). I will not be able to reference the early triggers specifically as I have never owned one. I am going to have to make some generalizations about similarities of both triggers that might be incorrect. So, feel free to correct my part numbers or generalizations.

    The early 2 screw pistol grip frames (1996 to 2011) have a metal side cover and, without taking the grip panels off, you can see a slotted screw behind the trigger guard. The 3 screw pistol grip frames (2012) have a plastic side cover and can be identified by an allen head screw above the trigger guard. I believe the fit and finish on the 3 screw plastic cover is superior to the older 2 screw model. However, it does require a more discerning eye when shimming the trigger and sear as it can flex if the space is overfilled.

    In the habit of replacing every screw with stainless steel, I generally prefer philips heads when available, which is not necessary to improve the function of the pistol. If you are planning to buy the allen wrench, and/or replace the screws I would advise removing the pistol grip frame from the pistol’s gas tube before bringing it to a hardware store. This could save both a lot of explaining and a visit from the RCMP. Removing the grip frame is accomplished by backing off the 2 screws, fore and aft, that can be removed with either a #2 square drive or a flat blade screw driver. Do not mistaken these for Philips heads. I remove the right side grip panel first to facilitate the removal of the aft screw. While at the hardware store pick up three or four #6 brass washers.
    Pic #12240 trigger mod 002.jpg

    I remove the pistol grip frame before commencing work to simplify handling and to gain visual and physical access to the trigger with the cover in place. Remember the small spring and ball bearing that index the safety, which is removed to work on the trigger and, I, personally, never replace the safety. You will see dust caps on my grip frame parts where the safety was once located. There are three main aspects of the trigger itself that will be addressed. First, is the side to side play in the trigger; second, is the amount of trigger-return; and, lastly, is the trigger face. Trigger pull weight and smoothing the trigger pull will be covered in the sear and hammer modification sections. This section is about getting a $25 trigger feel from $2.50 in parts.

    The presumed difference between the brass and black triggers is the widened face on the black trigger. I believe the contact area remains the same and Crosman’s wavy washer helps fill the gap. Unfortunately, if the gap is filled with something stiff and the wavy washer it increases the drag markedly.

    If polishing the three (this includes where the trigger touches the sear) contact surfaces with a dremil pad or 800 grit emery paper, it is best to do so before fitting the shims or stops.
    Pic #22240 trigger mod 005.jpg
    The 3 screw frame had tighter tolerances and needed less shimming. I shimmed the 2 screw frame on 2 sides. The wider shim needs to be on the frame side and the narrower shim on the cover side to center the trigger and the sear. I use a #6 brass washer for the frame side and if need be, cut an appropriate piece of plastic for the cover side. Not all the brass washers are the same width and they can be sanded down with 400, 600 and then 800 grit paper to give the desired thickness.
    Pic #32240 trigger mod 012.jpg
    Pic #42240 trigger mod 010.jpg

    A plastic washer can made by cutting or drilling a hole in a plastic lid or other thin piece of plastic and cutting around the hole to form a washer shape. Any plastic packaging can be used for this shim. I just find the piece of trash that fills the gap and does not cause excessive drag. In other words, the trigger should move freely under its own weight when shimmed and closed in the frame, without the sear and spring installed, by shaking the frame back and forth.

    Grip frame type…..Factory install play…..Total width of shims….After shimming play
    2 screw frame……..10/32 inches……………....0.034 inches………………..7/32 inches
    3 screw frame……..12/32 inches………………..0.024 inches……………….8/32 inches

    Tuning the trigger-return is extremely different between the 2 grip frames. The 3 screw frame is easiest to resolve with just a piece of duct tape between the trigger tongue and the grip frame.
    Pic #52240 trigger mod 017.jpg
    Unfortunately this impedes the removal of the cover and may best be saved for last. It also is something to remember when servicing other aspects of the trigger group and removing and replacing the cover.

    The 2 screw frame trigger-return was “stopped” with a piece of 1/8 inch ID and 3/16 inch OD vinyl tubing. The approximate length of the tube is 0.55 inches and it is then cut at an angle so as not to interfere with the trigger pull. The installation and dimensions are outlined in the picture below.
    Pic #62240 trigger mod 025.jpg
    If the angle-cut edge of the stop faces the trigger and the stop is seated on the bottom of the cover area, the stop will remove 0.209 inches of return travel at the tip of the trigger. This can first be tested without the spring or cover installed to be sure the trigger still moves the sear (to drop to the upper edge of the frame) to clear the hammer when the trigger is pulled
    Pic #72240 trigger mod 028.jpg
    and allows the sear (to rise above the frame) to engage the hammer when the trigger is released.
    Pic# 82240 trigger mod 031.jpg
    It is best to start too long and trim to fit the particular pistol. This must finally be tested with the sear and spring installed and the grip frame located back on the gas tube. It may take some successive approximation (trial and error) to get this working flawlessly. Also, further tuning of the sear may change the desired length of the trigger stop somewhat.

    When everything is operating correctly, I again remove the cover and trigger and form a sock from 0.170 inch ID and ¼ inch OD vinyl tubing. This sock fits on the black trigger, but may be too large in ID for the brass triggers. I first cut a sharp angle on the tube and push the point of that angle up the face of the trigger. When it can go no further, I cut the bottom edge close to the end of the trigger itself. This cut is critical to keep the “sock” from rubbing against the lower part of the trigger guard when the trigger is fully pulled. This increases the width of the black trigger from 0.187 inches to 0.298 inches.
    Pic #92240 trigger mod 036.jpg

    Before I go running off for the old lady’s nail polish to “loctite” the frame screws in place or pour gobs of graphite dry lube into the trigger group, I shot this a while
    Pic #102240 trigger mod 039.jpg
    and then performed the sear/spring modification to lighten the trigger pull. I believe I actually did perform the sear modification first… However, I am writing up the trigger mod first as it required the fewest parts, tools and finesse.

    As always, the results of others may vary from those shown above and the above information invalidates all warranties, expressed or otherwise, and is written for entertainment purposes only and should never be tried at home as it may be illegal, lethal or possibly damage your gun. Not to mention, you could shoot somebody’s eye out. The good news is that I post with public domain rights to reprint. Copy left with no Copyright!

    Shoot smart, shoot safely,
    Poor-man Plinker

  2. #2
    Senior Member sholo's Avatar
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    Sun Jan 1 2012
    Slightly north of "out there"
    Great post, PmP! Your fingers aren't sore from typing, are they? Unique "shoe", too. Never seen that before, I may try that someday.

    Here is another idea for the sear/trigger to lighten the pull weight a bit. Not my idea, but I tried it and it does seem to be lighter/smoother than just polishing the sear/trigger lobe alone.

    Drill a 3/32" hole 1/16" deep in the top of the trigger lobe, put a dab of grease/moly paste in the hole, and take the ball bearing from your safety (who uses the safety anyways, right?) and pop it in. Done deal! The ball bearing is much harder material than the trigger lobe and super smooth, plus there is a much smaller contact area between the two. Once you smoothen out the sear and polish it, it makes for a pretty nice trigger...well...for a 22xx trigger, anyways!
    trigger fix 002.jpgtrigger fix 001.jpgtrigger fix 003.jpgtrigger fix 004.jpg

    FYI, the spring guide in the last pic is a piece of gun cleaning rod, 3/16" diameter (fits perfectly in spring), cut to length so that it acts as a trigger overtravel stop, too (sear stops flush with outside diameter of tube). Drilled/tapped the frame 8-32, inserted rod with a light coat of moly paste, and a cut down 2240 hammer spring finishes it off. Try it out, you just might like it!


    Don't sweat the petty things, and don't pet the sweatty things!

  3. #3
    Thanks Todd,
    Everybody needs a hobby ha ha ha.I had seen the ball bearing "trick" afore... Thanks for passing it along. I have been attempting to provide the most Lo-tech, lo-tool solutions for the first time modder. I will probably do a couple of ball bearing mounts for my "target models" he he he Thanks for adding to the thread for the more adventurous viewers. As for the tapped cleaning rod (more giggling) I have about 3 or 4 non tool solutions for sear stops you might also like. Next post ha ha ha.

    Might i make a few of recomendations on your setup? You might place the shims on the frame and not the cover side as it will center the works in the frame as Crosman intended. And, i will cover this in the next post, but, a sear follower, of sorts, as was in the Medalist 1377s, stops the spring from shifting on the sear. And, I am sure you have heard of this before, a #6 spring for the sear spring. Sometimes they need to be preloaded with washers if there is not enough tension to "land" the sear on the hammer. But, I am getting ahead of myself. I will wear down the keyboard some more when I get back from Panama with the 22/17 sear mod. I like what you did and maybe you will repost it on the sear mod post?

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