Thursday, April 25, 2013

Crosman Quest 1000 Overhaul

Joe D, one of my new co-workers, heard a couple of us talking about various scopes the other day in the shop.  He asked if one of us could sight in his airgun.   He said "airgun"?   Oddly, I was immediately nominated.   Joe brought it in a couple days later and left it in my care.   Before taking it home, I asked if I could also go through the gun mechanically if necessary.  Joe green-lighted the request.

A Crosman Quest 1000 with a Crosman branded 4X scope. 

It's a .177 caliber spring piston rifle.  Safe to assume the "Quest 1000" name relates to velocity expectations.

Overall, the gun didn't look too bad cosmetically.  Joe bought the gun to deal with pests on his property.  Chipmunks, squirrels...  There were some minor marks on the stock.  Wasn't scratched so much as marked by something else.

The phillips head stock screws have got to go.   I'll replace these with button head allen screws.

Very thin surface rust covered much of the metalwork.  

As I started to cock the gun, I felt the action shift very slightly in the stock.   That sort of brought the sight-in project to full stop.

Kinda knew going into it that this would involve a full tear down.   Started by removing the forward stock screws and the trigger guard.  Fasteners were barely finger tight.  The gun was essentially rattling itself apart from the firing vibration.

With the stock off, the white marks were buffed out with bronze wool.


Bronze wool is much softer than steel wool and left the wood finish looking untouched.

The white marks simply vanished.

Set the wood aside and removed the stock lug brace from the link pin. 

Removed the oddly named "stock link pin".  Note:  This is the nomenclature that Crosman uses for the part (B18-00-9) on their EVP drawings.

This e-clip,

the anti-bear trap lever, and spring were next.  


 Removed the barrel pivot bolt.

Pulled the barrel and breech block assembly from the compression tube.

Didn't know how much preload was on the mainspring.  Set it up in my spring compressor and drove out the cross pin with a brass drift. 

Turns out, the mainspring preload was minimal.  Only about an inch of compression was on the spring.  This gun doesn't need a compressor to repair.

Plastic end cap, the steel cross pin, mainspring and spring guide. 

The entire trigger unit is pushed backward and out of the compression tube.

Finally, the piston can be removed from the tube.

Piston seal is damaged on the edge.  This often happens during initial assembly as the piston is inserted into a compression tube that was never deburred along the cocking lever slot. 

Used a Flex Hone from Brush Research to cross hatch the forward (inside) end of the compression tube.  This leaves very fine scratches that trap and hold lubricant.  After flex honing, the tube was cleaned and dried.  Then a very thin layer of a 60% moly grease was burnished into the tube.

All the exterior metal was cleaned and rubbed down with Boeshield T-9 oil.  That would be rust on the rag.  Most all of the rust came off the gun with little damage to the bluing.

While it was apart, I deburred everything.  Polished the rear of the piston body.

Removed the spring-loaded breech lockup detent.  Buffed it then reassembled with moly grease.  The barrel pivot bushing was also cleaned and greased.


Went though my seals and found a handful.  Got these from Crosman a while back. This is a really common seal and at about $1.50 each, it's painless to have a few set aside.   The seal is Crosman part number B18-04-1A.

Installed.  I burnished the sides with a really small amount of moly before installation.

Mainspring got a thin coat of copper anti-seize.

Greased the sear contact faces of the trigger before reassembly.  Gun went back together easily without the spring compressor.   The only trick was getting the uppermost front tab of the trigger unit in position.  The piston assembly must go into the compression tube first (and don't forget to line up the sear notch in the piston body with the cocking lever slot )--then the trigger unit can be installed.  It's necessary to use something like a dental pick to pull that front tab downward as the trigger is slid into place otherwise, it won't seat properly to the compression tube.  (It'll be obvious)   After that, install the spring, plastic endcap  and the cross pin.  It's a straightforward reversal of the disassembly.  

After a quick sight-in at 10M.  10 shots off-hand with Crosman Premier Hollowpoints.   Since he isn't a crazy dyed-in-the-wool airgunner, it made sense (well, to me at least) to zero the rifle with a pellet he can readily find in the local mega stores.

Joe knew that he'd have to fine tune the scope adjustments to accommodate subtle differences in how he holds the rifle.  Also gave him a couple tips on the artillery hold.  While Joe was amazed at the change in firing behavior after the lube/tune,  I was impressed with the accuracy. 

Not sure what's on deck for next time, but thank you for reading and please check back soon.


Andre said...


This was a great post to read. You did an excellent job documenting the process too. It's great to have a workshop that is capable of tuneups like this. I still know too little about airguns to do any sort of overhaul but it reminds me of bikes which I know a lot more about. (I've noticed a few bike tools in your shop too). Tearing down an object, cleaning, polishing, lubricating, and properly adjusting goes a long ways. While riding a bike or shooting an airgun can be fun sometimes it's the project aspect that is fulfilling and it's nice to be able to help a friend or acquaintance. Thanks again for this post.

t-bone said...

Great work, great write-up.

Andre Gross said...

Nice work!
Last summer I overhauled my quest.
It tool 4 months for crosman to send parts, but not it shoots better than ever.

Slinging Lead said...


How did I know you would find an excuse to do a complete strip down? Joe couldn't know how lucky he is to have you as a coworker.

Awesome shooting by the way.

Slinging Lead

Brandon said...

My father has the exact rifle and I was hoping to tune it for him and I will likely follow your example. My question is, your flex hone, what size and grit did you use? I'm thinking of ordering one for use on his rifle.
- brandon

derrick38 said...

Mine is pretty well-worn, but it started life as a 1-1/8" diameter 180 grit silicone carbide model. It's so worn, there's no way it measures that large today.

If I was ordering a new one for this rifle , I'd probably get a 1" and a higher grit--maybe 240. Don't go finer, as you want to cross hatch the inside of the cylinder. Flood the tube with a cutting oil and be anal retentive about cleaning the tube thoroughly after use. It's about a 10 second job as you don't want to change the tube's dimensions. You'll also need an extension to get the hone all the way into the front of the compression tube. I use a drill bit extender from Irwin.

Brandon said...


Thanks so much for the info!


Nicholas said...

excellent job Sir

Anonymous said...

I'm 70+ y/o and besides tearing into a 20mm Vulcan aircraft gun or a 22 rimfire, I've never seen such a great article about how to fine tune the internals of a springer. Thank you, this may be an old post. But a winter project will keep me occupied. Thanks for the info, photo an well written up tech manual you have presented to us, a large group of novices. Happy shooting, sincerely, jb1rd.

derrick38 said...

Thanks for the comments. You can have this rifle finished in a couple hours and save your time in the winter for 20mm electric cannons.

Anonymous said...

Great writeup, thanks. My stock screws are always coming loose and wondering if those button-head Allen screws would hold better. I would like to replace mine now after reading this blog. Do you know what size screws I would need? Thanks, Charlie.

derrick38 said...

It's been a while, but they're probably metric. M5x.8mm is my best guess. Head type isn't going to help prevent loosening. Tune to reduce vibration and use a thread locking agent like Loctite.

Anonymous said...

Found the screws on the Crosman website parts diagram (C1k77). The screws are M5x14 and not an easy size to find. After striking out at Home Depot, found the closest match in a local hardware store with a great selection of nuts and bolts. Best I could get was M5X16. These are about two thread lengths longer than needed, so I trimmed them with a dremel. Upon close examination of the Philips head screws from the factory, they appeared to be trimmed as well to fit. M5X14 is an odd-ball size. I am very pleased with these Allen heads as opposed the the Phillips in the gun. Much easier to snug them in compared to the factory screws. I noticed a small amount of side to side play in the barrel when opened and turns out my Break Bolt needed to be tightend. That tightend up to about a full 1/2 turn before snug. I got a little daring and pulled the trigger out of the trigger housing. If you notice in the closeup pics of the trigger in the blog how one end of a trigger spring extends out to the trigger adjustment screw. After messing with it a little, I came to the conclusion that didn't need extend that far so I trimmed that down so it is not resting up next to the adjusting screw. I reinstalled and the trigger is working fine. I may look for a slightly longer trigger adjusting screw to try and cut the length of pull a bit more. I have the adj.screw down as far as it will go now but I think it can be improved. I remember when I first purchased this gun about 10 years ago I hated it...couldn't hit anything with the gun. However eventually I did learn about using the artillery hold on spring guns and they are very accurate. Thanks again for the great writeup.