Thursday, August 12, 2021

Crosman 1077 - Putting it back together.

 Hi All,

So I attempted to replace the end seal and reassemble my 1994 Crosman 1077 pellet rifle.

So here is the the Plug Assembly (1077-036) broken down into its component parts.

Showing the dirt and wear on the Piercing Pin (38A027) and the cracks in the bottom of the End Seal (38-128)

Brand new End Seal for comparison,

I then cleaned all the parts with Q-tips and 91% isopropanol. I'm sure 70% would have been fine.

Plug Assembly reassembled. Piercing Plug, Screen, Piercing Pin, End Seal, and Guide Collar.

Plug Assembly goes back in the Tube (100-017).

You want to line up the pin side with the hole,

and the tube side with the notch.

Theoretically you still have the pin in your vice grips.

You just reverse the process and push while twisting.

The Tube (1077-017), Spacer (1077-039), and Barrel Housing (1077-010) are all held in place by the Barrel Band (1077-008).

Here they are assembled. Just tight the Band Screw (1077-026).

Next fit the end of the Transfer Tube (1077-016) into the Plug Tssembly (1077-036) via the tube Bushing (1077-029).

Next, find the part you didn't know existed until you saw it fall out of the Receiver when trying to put things together. That would be the Hammer Roller Pin (106-024) under the metal arm of the Trigger Assembly (1077-033).

This next step is very important. Drop the Valve and Tube Assembly (1077-034) and Trigger Assembly (1077-033) on the floor, thus learning how to disassemble a portion of the Valve Assembly into its component parts. Realize you only have Detent (106A011, which is then called 106B011 in the list) and Detent Body (106A010) but not the Detent Spring (106A046) because of course you didn't see where that went when it hit the floor. Grab a beer.

Don't give up and eventually find said Detent Spring.

Reassemble the Valve and Tube Assembly. Now we're cooking.

Get the Receiver together with all the assemblies put back together correctly, for the third time after having springs be springy.

Insert a cylinder without the stock on to see if it leaks. It seemed to hold.

Put the stock on with the three screws, remember that the one furthest from the trigger is a bigger diameter than the other two, but by now you've pulled this thing apart so many times that's not difficult.

Find a target online or go old school and draw an X on a piece of paper. (Sorry for the gratuitous broken toe shot.)

I then went outside to try and sight it in at about 10 paces.

I got off one shot, then realized I left the Allen wrench for adjusting the site inside. I came back out, lined up my second shot, finger on the trigger and...


Somehow it started leaking again. I tried some in situ adjustments of the guide collar and then had a hard time getting the cylinder to pierce. Finally I figured that maybe I just need a new piercing pin. It is, however, possible that the gun is leaking at the plug assembly and tube junction.

So I'm waiting on the new part. In the meantime the replacement 1077 arrived and my brother and I spent about an hour shooting cans and targets. It was great fun.

So the jury remains out on whether I can resuscitate this gun. I'm at the point where I don't want to spend anymore to fix it because I'm halfway to the purchase of a brand new one. I'm also running out of time. So we'll see if I have anything further to report.

Happy hobbying.


  1. Never tackled a repair on an airgun before, but this post was very interesting to follow mate. I "have" worked on repairing my bolt action shotgun, and assembling my cheap turkish pump action (Which strangely came in pieces.). Realised at the time that I knew far less about guns than I thought! LOL Thank goodness for knowledgeable friends.

    1. Hi Dai, yeah I know very little about guns. I figured it was worth a punt to try and fix it because otherwise it's just trash. The new pin came in yesterday but I have a lot of stuff to do, so not sure when I'll have the time.

  2. I particularly appreciated the step where you had to redo everything because the pieces fell on the floor... that would be me I am sure!

    Hopefully the new part fixes your problem!

    1. Hi Lasgunpacker. Yeah I seem to have one of those moments every time I'm doing some kind of repair and then I have to figure out how to save the project. Being very stubborn helps in those situations. I hope the new pin will work. It's a nice gun when it's operational.

  3. Hay Sean IV been reading this and could do with ya help IV found a little spring and don't no where or how it goes it lol help me plz lol

    1. Hi headshots, to my knowledge there are only three springs in this gun. The main one that falls out is the spring from the trigger assembly. The fourteenth picture in this post shows how it goes in. I found the Crosman manual and parts list very helpful. I just found a copy online.