Introduction: Crosman 2100 Trigger Mod (and Reassembly!)

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The Crosman 2100 air rifle is alot of fun. Its fairly quiet and can be shot indoors with nothing more than a cardboard box. Its pretty darn accurate, and dime sized groups at 30 feet are not to hard to get off hand. It also has good iron sights, and its really inexpensive (~$70). Plus there are no cartridges or gas to buy, and no goofy recoil like a springer.

However, the trigger is hands down the worst trigger I have ever encountered.

I am sure there is some beat up Enfield or Mosin-Nagant out there with a worse one, but my recent production 2100 had something like a 9 pound trigger with four to six stages. Every time I thought it would fire, I would squeeze a little harder, only to have the trigger slip slightly, and then encounter even more resistance. Eventually it would fire, but by then my breathing and hold was all screwed up.

Fortunately, this is easy to fix. I have only ever installed drop in triggers, and I was able to get a far better trigger with only a little bit of work and 50 cents worth of additional parts (1 3/4" ID o-ring).

However, looking over a lot of internet threads it appears these rifles can be somewhat challenging to get back together and functioning. As such I have put together, an instructable detailing the trigger modification, and perhaps more importantly, how to put a Crosman 2100 back together. The only tools needed are a flat bladed screwdriver, and some patience. A handy chart of all the parts can be found here.

Step 1: Disassembly

This is the easy part.

Make sure the gun is unloaded and any air pressure relieved. Then remove the three bolts from the receiver, and carefully pry apart to the two halves. A flat bladed screwdriver, guitar pick, or something other prying tool comes is handy here. If you want an adventure leave the bolt handle side down, and quickly separate the two halves. You will be rewarded by springs and other parts flying in all directions. Those who are less adventurous may want to flip the gun over and place the flat side of the receiver down. Open the two halves about an 1/8 inch and carefully remove the bolt hold open detent and spring. If you are careful everything else should stay in place.

Next take out (order is approximate): the interlock, interlock washer, and interlock pin; the cocking arm detent; the bolt knob and spring; the trigger, trigger spring, and trigger pin; and the sear spring, sear pin, and sear.

The barrel and the rest of the parts can now be lifted out. Just watch out as the tube plug and spring, and the BB pusher and spring will both go flying. The former can be avoided by putting a drift pin (or one of the bolts) into the middle bolt hole to hold everything in place.

Step 2: Trigger Modification

The contact surfaces on the trigger and sear looked pretty good. All of the grittiness appeared to come from the very deep tools marks left on striker. At the indicated spots I removed the tools marks on the sear with a 1000 grit stone, and then polished them until shiny with a 4000 grit stone. I took the same approach with the trigger. This was my first attempt at a trigger modification, so I just tried to remove a tiny amount of metal and not to reshape either part. I believe Crosman sells all of these parts, so one could get a little agro, and risk having to order new ones.

The striker required alot of work. I sanded it with 1200 grit sandpaper to all of the tool marks were gone, while trying my best to keep the angle constant. During the trigger pull the sear pushes the striker back about 1/16 of an inch, so changing the angle on the striker (or the sear!) here could help lighten the pull, or make the gun go off unexpectedly. Be careful.

The trigger pull on the 2100 feels a mile long (its ~ 1/10,560 th of that). There are several approaches one could take to lighten it. 1) Install a set screw on top of trigger, slightly back of the circle thing. 2) Shorten the sear. 3) Limit the travel of the sear. The first two approaches give a single stage trigger. The third produces a two stage trigger, which is what I was aiming for.

Its supposedly possible to drill and tap the pump tube and install a set screw to limit the sears travel. Being a fan of "easy" I elected to slip a 3/4" ID o-ring over the pump tube and into the grove that is conveniently there for some unknown reason. This produces a trigger that first requires a very light (and distinct )1/4" pull, followed by and 1/8" region where the trigger breaks like a carrot, albeit a carrot that has been in the fridge a bit too long. The result is less than ideal, but 10K times better than the factory trigger. Shortening the sear, or changing the striker/sear relationship could yield a very nice trigger, I suspect. The overtravel is a little large for my liking and I might add a pad or a set screw underneath the trigger to limit it in the future.

I was able to drop the rifle on its butt from about 3 feet, and on its side as well. In neither case did he rifle discharge. As such the trigger seems safe. YMMV.

Step 3: Putting Things Back Together: Getting the Barrel Back in the Receiver Halve

1) Put the striker, striker spring, and tub plug into the pump tube. Use a bolt or drift pin to hold everything in place (picture).

2) Slip the BB pusher into its spring. Place the BB pusher and spring in the white plastic thingie (picture).

3) Place the bolt into the breach of the inner barrel (picture).

4) Carefully maneuver the white plastic thing over the bolt. Some dicking around is necessary as the little rod on the striker has to pass thru a slot in the white plastic thingie, and thru a specific slot in the bolt (picture).

5) Make sure the hole in the pump tube and the plug in the barrel support line up.

5) If the BB pusher fell out place it back in the white plastic thingie with the handle pointing up.

Now the fun part. With the BB pusher handle pointing up, lower the receiver half with the groove for the BB pusher down onto the assembly. One needs to slip the receiver over the BB pusher without knocking it over. With practice this is pretty easy. The first time is pretty challenging.

Once the protrusion on the barrel support, and the hole on the pump tube are lined up with the respective features on the receiver, everything will snap into place with a very satisfying click. The pin/drift/bolt holding the tube plug and spring in place can then be removed.

Note: If you don't plan on using BBs (as they erode the rifling in the barrel) the BB pusher and spring could be left out. This would make this step considerably easier.

Step 4: Putting Things Back Together: Reinstalling All the Little Do-dads

1) Very carefully pry the barrel assembly partially back out so that just enough room is made that the bold hold open detent and spring can be reinstalled (picture). Squeeze back in place when done

2) Place the bolt handle and spring in place (picture). This requires some fiddling with the white plastic thingie.

3) ORDER IS IMPORTANT. Place the sear in place, then the sear pin, and finally slip the sear spring into place.

4) ORDER!. Place the trigger pin, trigger, safety, and trigger spring into place (see picture for details). Move the safety to the safe position to make sure the spring is lined up correctly. I would test the trigger pull at this stage, and make sure everything works.

5) Place the interlock pin, interlock, and the interlock washer in place. Note: while these parts are in the picture, I left these out in the end. (Keep your bogger hook of the bang switch while the breach is open, and all unpleasantness will be avoided !!!!)

6) Place the pump detent in place.

Step 5: Putting Things Back Together: the Final Challenge

Now its time to to slip the receiver halves back together. It helps to have the safety in the safe position so that it lines up with hole. It also helps to have the pump open so that the pump handle detent is not knocked out of position.

Go slow. Once everything is almost in place, use a very small screw driver to push the sear spring into the correct position (as shown in the picture). It starts out braced against one half of the receiver (the one with the BB pusher grove), but it needs re-positioned to the other half so that it does not bind.

Once the sear spring is in place squeeze the two receiver halves all the way together. I would test that the safety, bolt, and trigger all work as inspected. The three bolts can then be reinstalled, and tightened tight, but not too tight. If these three bolts are over tightened the bolt will bind.

Enjoy.

Step 6: Epilogue: the Four Rules of Gun Safety

Enjoy and remember the

Four rules of gun safety

1) All guns are always loaded. (Isn't this a rather dubious claim, rather than a rule? As Jeff Cooper was an extreme nag when it came to diction, and I always thought this was a rather odd mistake. "Treat all guns are they are loaded," which I believe was the intended message is a rule, but it makes rule #2 somewhat redundant).

2) Never point the gun at anything you are not willing to destroy.

3 ) Keep your finger off the trigger until your sights are on target.

4) Be sure of your target and what is beyond it.4 (Isn't his rule #1 / #2 again?)