Part 1
Part 3
Part 4

In the first part we checked out the rifle, removed the busted scope and wonky sights, fitted a scope and checked for accuracy, albeit at short distance only. In this part we’re going to disassemble the rifle and check out the internal parts.

Crosman Optimus with Leapers 6-24X50AO scope mounted
Initial disassembly of the Optimus is pretty straightforward. Remove three Philips’ head screws, one at the rear of the trigger guard and one on either side of the forearm.
Now the action lifts easily out of the stock.
Note the Anti-Bear Trap bar that links the cocking mechanism to the trigger group.

Next on the agenda is to disassemble the barrel from the compression tube. Note the large bolt at the joint, this has to come out.

First, “break” the barrel open, this releases the tension on the bolt and allows it to turn relatively easily.

Use a well fitting screw driver to turn the bolt out. See how the threaded portion is smaller than the bearing portion? It only goes in and comes out in one direction.

This example gave me fits at first. It was necessary to close and open the rifle before the breech would start to slide out of position and allow it to be further withdrawn.

There’s a plastic/nylon/synthetic of some kind washer on either side of the breech block. This acts as a bearing and helps to keep the ears of the compression tube from scoring up the breech block. It fits in the recess around the hinge pin. Note the amount of grease in the groove and the total lack of any around the bearing.
After separating the barrel from the breech block the two pieces didn’t completely separate yet as the Anti-Bear Trap was still attached and I didn’t want to force the cocking piece out of its place in the compression tube.
Next, remove the stock lug/rear spring guide bolt. Note the presence of a brass washer between the trigger mechanism and the compression tube.
I like to dismantle the rest of the rifle while in a spring compressor for safety’s sake. You never know how much preload will be on the spring and it’s easier to control this way.
Put just a bit of pressure on the back of the spring guide assembly then carefully drive (or push) the pin out. Then back off the compressor allowing the spring to decompress. There was 1.370″ of preload on the spring.

Once the tension was off the spring I was able to wiggle the trigger pack out and then unhook the Anti-Bear Trap mechanism from the cocking arm. Note that piece that’s sticking up at about a 45* angle. Pay attention to how it lays in place as you’ll have to position it just right to reassemble the rifle.
Note that “T”stud, that’s the bit that guides and retains the ABT bar. Above it is the “cocking shoe” which is actually just a part of the cocking arm itself.
Here’s a look at the mainspring still “in situ”. Note the poorly finished coil giving just a bit more than 50% contact around its circumference.
Here’s a look at the spring on the rear guide, pushing against the trigger seat.

Here’s a look at the tophat, spring, rear guide and piston.
And here they are fitted together as they are inside the rifle, but uncompressed.

The first closeup of the seal makes it look like there’s some kind of metallic film covering it. That’s just light reflecting from the flash.
Angling the seal slightly you can see that it’s just discolored from combustion and that it’s got a flat spot on the edge that’s at about 8 O’clock in this picture.


So, here’s some data:
Piston Clear depth – 5.185″- 131.7 mm
1.370″ – 34.8 mm – Preload
36 coils – 1.23″ – 3.124mm wire
Piston with seal – 193 grams
Piston with seal and tophat – 226 grams
Tophat – 33 grams of ill fitting steel

Overall the rifle’s in fairly good shape. I’m guessing that the seal is partially to blame for the high SD in the chronograph string we looked at. Now we move on to tidying things up and getting the rifle ready for reassembly.