Canadian Airgun Forum

The #1 Community for Airguns in Canada!
It is currently Sun Oct 24, 2021 10:39 am

All times are UTC - 5 hours


The Canadian Airgun Forums are a place for people to discuss and learn about airguns and the airgunning sport in Canada. There are lots of discussions about airguns, airgun accessories, reviews, modification and repair information, airgun events, field target and free classifieds!

 

You need to register before you can post: click the register link to proceed. Before you register, please read the forum rules. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload your own pictures, and access many other special features. Registration is fast, simple, and absolutely free! To start viewing messages, select the forum that you want to visit from the selection below.






Post new topic Reply to topic  [ 8 posts ] 
Author Message
PostPosted: Fri Sep 03, 2021 4:07 pm 
Offline
Site Moderator

Joined: Sat Sep 03, 2005 9:25 am
Posts: 3844
Location: Ontario, Canada
My favourite .177cal Crosman Optimus was acting up recently when it spit a bent up washer out of the trigger guard. At first I thought it was a small piece of mainspring because the rifle wouldn't cock for me a couple of times. I disassembled and saw that the thin washer I had installed on top of the short spacer was missing. It took well over 4 years for the spring to cut through this weak washer. The rotating spring finally wore through it.

I pulled the piston, guide and spring, cleaned everything up and relubed with moly paste prior to assembly. The compression chamber was cleaned and a micro thin coating of moly was polished into the walls. The piston, guide and spring got a light coating. I mixed some moly paste and 30W oil and worked it into the cocking lever pivots, barrel wedge, and trigger pivot pins. Moly paste to trigger contact areas. Loctite to the screws and the rifle sat for a day. I was expecting the loud report and dieseling after the first few shots but only smelled a slight trace in the air... but no loud report. I guess I finally learned to go easy on the paste in the chamber. I cleaned the barrel after 10 shots and then shot 5 foulers. I followed up with the following 5 groups of 5 shots each from 10 metres (from rest). They were shot in this order.

.17, .19, .22, .21, .20 = Average .20" ctc

After the groups, I clocked 5 shots through the chronograph (8.64gr H&N FTT).

727, 730, 724, 726, 723 = Average 726 fps

This Optimus spring has been in the rifle since purchased in Nov 2016. It has seen many thousands of shots. When new, the spring was pushing CPHP at 960fps but I quickly detuned it because of the harshness. With a shorter spacer the same 8.64gr H&N pellet shot an average of 758fps. It's lost about 30 fps since new. Not a concern at all for a 50 yard plinking rifle.


Attachments:
Optimus at 10m 001.JPG
Optimus at 10m 001.JPG [ 588.17 KiB | Viewed 134 times ]
Top
 Profile  
 
PostPosted: Fri Sep 03, 2021 4:45 pm 
Offline

Joined: Wed May 12, 2021 8:34 am
Posts: 89
Interesting. I have used some plain washers as spacers (ground to diameter and bored out as required). I have polished them somewhat and lubed with molly. Your experience suggests that I should open it up for an inspection periodically.

Question:
What do you use to clean the compression chamber? I have used mineral spirits and it seems to work well as a degreaser.

Enjoyed your posting as always!

Rob27


Top
 Profile  
 
PostPosted: Fri Sep 03, 2021 6:52 pm 
Offline

Joined: Mon Apr 12, 2021 11:04 pm
Posts: 201
Location: Lower Mainland, BC
TCooper wrote:
My favourite .177cal Crosman Optimus was acting up recently when it spit a bent up washer out of the trigger guard.
Cool story! Glad the washer didn't chunk the rest of your rifle. And still shoots straight! Very straight. Optimus Prime indeed.

_________________
Stephen

Cometa Fusion .177 495 fps, Hawke Airmax 3-9x40
Crosman Optimus .177 495 fps, Ohhunt 3-9x32 AO IR
Crosman Phantom .22 495 fps, Hawke Vantage 3-9x40 AO
SPA WF600 .22 495 fps


Top
 Profile  
 
PostPosted: Fri Sep 03, 2021 7:06 pm 
Offline

Joined: Wed Sep 07, 2016 11:04 am
Posts: 1157
Quite impressive for a budget shooter. A great example of what is possible if you nail the setup and hone your skills.

_________________
I have some airguns.


Top
 Profile  
 
PostPosted: Fri Sep 03, 2021 7:35 pm 
Offline
Site Moderator

Joined: Sat Sep 03, 2005 9:25 am
Posts: 3844
Location: Ontario, Canada
eSteve wrote:
TCooper wrote:
My favourite .177cal Crosman Optimus was acting up recently when it spit a bent up washer out of the trigger guard.
Cool story! Glad the washer didn't chunk the rest of your rifle. And still shoots straight! Very straight. Optimus Prime indeed.


Yup, that's why I pulled out the guts. I was somewhat expecting to see bits of metal washer embedded in the piston seal but I guess it all dropped out. Everything looked fine inside. The replacement washer is quite thick and won't be a problem.


Top
 Profile  
 
PostPosted: Fri Sep 03, 2021 7:45 pm 
Offline
Site Moderator

Joined: Sat Sep 03, 2005 9:25 am
Posts: 3844
Location: Ontario, Canada
Rob27 wrote:
Interesting. I have used some plain washers as spacers (ground to diameter and bored out as required). I have polished them somewhat and lubed with molly. Your experience suggests that I should open it up for an inspection periodically.

Question:
What do you use to clean the compression chamber? I have used mineral spirits and it seems to work well as a degreaser.

Enjoyed your posting as always!

Rob27


Originally I think I used WD40 on paper towel to get most of the factory mess out of the tube. Then a splash of rubbing alcohol on clean paper towel. Then dry paper towels. I have an old .22cal cleaning rod with a nylon slotted tip that works great. I can insert the paper towel into the slot and twist the rest around the aluminum rod like a big tampon. Once the tube is clean, I use a cotton patch saturated with moly paste and burnish it into the chamber walls with an electric drill. I keep straightening out and loading up the patch with more moly. Then I wipe out the excess. This time, when I tore down the rifle, I just wiped out all the old moly with dry paper towels. Then applied fresh stuff with a patch on the rod.


Top
 Profile  
 
PostPosted: Fri Sep 03, 2021 7:57 pm 
Offline
User avatar

Joined: Fri Jan 22, 2010 1:17 pm
Posts: 2823
Location: Kingston, ON
Well, the results speak for themselves - both the rifle and the shooter are honed, good work! :drinkers:

_________________

Duke ))))----//----------==


Top
 Profile  
 
PostPosted: Fri Sep 03, 2021 10:24 pm 
Offline

Joined: Mon Apr 12, 2021 11:04 pm
Posts: 201
Location: Lower Mainland, BC
TCooper wrote:
I have an old .22cal cleaning rod with a nylon slotted tip that works great. I can insert the paper towel into the slot and twist the rest around the aluminum rod like a big tampon. Once the tube is clean, I use a cotton patch saturated with moly paste and burnish it into the chamber walls with an electric drill. I keep straightening out and loading up the patch with more moly. Then I wipe out the excess. This time, when I tore down the rifle, I just wiped out all the old moly with dry paper towels. Then applied fresh stuff with a patch on the rod.

Man, this is great. I had read previously about burnishing moly into the compression chamber but wasn't too sure. I can do it! I've done similar things in there, I have the tools. I've got a shotgun cleaning rod with a cotton mop, I tape the end of a strip of paper towel to it and wrap it around a la Kenny (RIP). I've got a nylon slotted tip, too. I've wrapped that with blue painter's tape to build it up and make it thick. Then I cut squares of sandpaper, apply spray adhesive to the back of them and adhere them to the painter's tape, to make a cylinder.

I sometimes get the feeling that my Optimus may need a new piston seal, it seems to want frequent drops of silicone. This moly burnishing would be rad. Thank you.


Attachments:
IMG_0620 copy.JPG
IMG_0620 copy.JPG [ 196.63 KiB | Viewed 84 times ]

_________________
Stephen

Cometa Fusion .177 495 fps, Hawke Airmax 3-9x40
Crosman Optimus .177 495 fps, Ohhunt 3-9x32 AO IR
Crosman Phantom .22 495 fps, Hawke Vantage 3-9x40 AO
SPA WF600 .22 495 fps
Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: Bing [Bot] and 11 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
News News Site map Site map SitemapIndex SitemapIndex RSS Feed RSS Feed Channel list Channel list

Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group

phpBB SEO