GTA
Airguns by Make and Model => Crosman Airguns => Topic started by: Camel73 on July 01, 2016, 03:26:51 AM
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Found this in my Titan NP .22 and thought I'd share and see what others think about it.
I've put mainly Premier ultra magnums through it, about 500 shots. Last week I put 10 shots through the chrony which averaged 720 fps.
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The seal needs to be replaced.
The two nicks on the bottom of the seal in the picture are allowing compressed air to leak past the seal. This drops your velocity and causes the piston to hit the end of the compression tube harder than it should. It appears from the picture that the piston is peening already. This condition also causes that "scope killing recoil" from the piston crashing into the end of the compression tube. Very common problem with the B18 Crosman variants that use a gas strut or nitro piston.
Give the gun a lube-tune and replace the seal. Your gun will shoot faster, kick less, last longer, and shoot more accurately with a larger variety of pellets.
Rick.
ps. You might want to check your breech seal when you get it back together. Tissue paper and dental floss...
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The seal needs to be replaced.
Give the gun a lube-tune and replace the seal. Your gun will shoot faster, kick less, last longer, and shoot more accurately with a larger variety of pellets.
Rick.
ps. You might want to check your breech seal when you get it back together. Tissue paper and dental floss...
Point repeated and pay special attention to doing a proper deburring. I've seen worse but it is a bugger when the burrs aren't properly addressed.
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Yup ... the super heated air created during the firing cycle leaking past a nick in the seal burns away at the nick and creates a trough :P
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I didn't even notice the peening... looked down the tube and it's mirrored. Kind of bummed about getting such an obvious defective seal. I took the stock off before I shot it and the safety spring wasn't connected. ??? It was the last one there out on the rack.
Oh well, good thing I got it instead of some youngster who actually wanted to hit something, ha. Groups are really bad. Brass washers are on my shopping list but everything is closed... Canada Day eh :)
Here's a couple pics of the outside of the piston cylinder,. Was wondering if this will resolve itself with proper care.
... and another pic of the breech seal.
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Thank you for the replies. Hmm.. let's try the piston cylinder pics again.
Any tips on where to get a quality seal?
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Thank you for the replies. Hmm.. let's try the piston cylinder pics again.
Any tips on where to get a quality seal?
Air rifle headquarters .... James Macarri Inc.
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I'd dress those scrapes with a fine file then polish smooth with a dremmel & polishing compound, looks like it was the cocking slot that has the sharpies causing the piston scraping so deburr and polish that too especially on the underside where the piston slides past.
The cpmpression chamber would also be the focus of special attention, inspect with a flashlight for any scraping, you'll need to polish those out too, some 220 and or 360 depending on how bad, finally CLEAN CLEAN CLEAN and clean again until absolutely microscopically clean, put it back together with kit gloves and a little moly goes long way.
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Could also glue some 'buttons' on that piston. I have used spray-on, dry lube moly on piston skirts and upper inside of the main tube where the piston runs during cocking. A few coats (let dry between) to prevent metal to metal contact.
https://www.zoro.com/crc-dry-moly-lubricant-aerosol-can-16-oz-03084/i/G1197034/?utm_term=A_PB20_Fluids&utm_source=bing&utm_medium=cpc&utm_campaign=PLA_US&utm_content=PB20&gclid=COmt6tO41s0CFSv5MgodWgwAHw&gclsrc=ds (https://www.zoro.com/crc-dry-moly-lubricant-aerosol-can-16-oz-03084/i/G1197034/?utm_term=A_PB20_Fluids&utm_source=bing&utm_medium=cpc&utm_campaign=PLA_US&utm_content=PB20&gclid=COmt6tO41s0CFSv5MgodWgwAHw&gclsrc=ds)
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Last gun on the rack?
It was probably dry fired in the store ... And maybe left cocked for days, weeks ...
I looked at the local Cabela's a couple days ago. All the break barrels on the rack (out of box) were already cocked, although some had trigger locks to prevent firing.
.
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Well, I cleaned up the piston cylinder but I thought it was strange that scuff marks were near the seal too so I looked down the length of the tube towards the seal and... no seal. Off center, I believe, check the pics.
Is that what a breech seal looks like after 500 shots? I should have ordered one of those too I suppose. Yesterday I put the order in for 2 small apex and some moly paste..
The button trick looks like the way to go, I'll have to research it some more... tolerances are pretty tight in there.
Am I wasting my time waiting for seals when I should be getting a new piston cylinder? or writing the company? Lol... eye roll
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Check it again after you have installed the new seal. The OEM seal may have been distorted from a bad installation. A burr on the reverse taper could push the seal to one side too. If the reverse taper is that far off center, the piston should probably be replaced. Crosman OEM parts are cheap and available.
You can temporarily soften the new seal prior to installation by immersing it in hot water.
The old seal is sometimes difficult to remove. If you can manage it without shoving a small screwdriver through the fleshy part of your hand, you're doing better than many of us here.
Your breech seal appears to be undamaged, but installed higher on one side. I'd remove it, clean up all the burrs and reinstall with a few wraps of dental floss underneath. Lay a piece of tissue paper over the breech, then fire the gun with the pellet you normally use. If the tissue paper stays put, you're good (no leaks). If the tissue paper flies off, you have a leaky breech seal.
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Those new seals look pretty good, and tough. The old one came off pretty easy.. I remember it being a little loose, but not the new one! Ha, super tight and no glaring concentricity issues like I thought, although I never did actually measure it.. I threw in another pic of the old seal to show what the inside looked like :o
After taking the od down while test fitting, I got it down to about 12 lbs pressure on the old fish scale and it seemed consistent through the tube. After firing it a bit I took it apart to inspect - the piston cylinder was noticeably easier to move. CPHP 14.3's average was 625 fps. Hmm...
Groups were still huge but not grotesque, ha. 3-4" at 20 yards. So I went down back and got me some fender washers... thinned them out too much, lol. Ok, you little... next was brass self locking nuts. De-nutted the little suckers with a hacksaw and voila! Brass washers. If you're wondering why I went through this instead of buying them, I did... any brass (or regular) washers weren't thick enough. At this point I did get some worthy results.
Target guide:
- RWS superdome pellets
- Center (about 8 yards) screwin around, gettin above center
- Top left (20 yards) 6 shots, not taking too much time
- Bottom left (20 yards) Took 6 more shots, made an adjustment to center, took my time, and bammo! bout a half inch 3 shot group
- Bottom right (40 yards) I didn't touch the scope and I can't remember where I was aiming, the target above or the end of the bigger right leaf, but just got lucky actually being close. Just wanted to get a group size. I was going to take 10 shots but 7 and 8 missed altogether
- Top right (20 yards) 2 shots - screws began to loosen up. No locktite yet, still r&d.
This was with a Simmons 3x9x40SP off my marlin model 60SS.
When I first put the brass washers in, the barrel was a bit stiff but after the RWS superdomes I tried CP hollow's and magnums, Benjamin variety pack (all of these roughly 14 grains) and Crosman powershot penetrators at 16.7 grains.
While testing these, the barrel got to swinging free again, checked the pivot bolt and still tight. At this point I wanted to put some muscle on it but thought against it.
Groups have opened up a bit again and I keep finding the pellets wanting to go right... I believe locktite will solve the wanting to go right.
The machine work is pretty rough on this thing so I'm thinking the brass washers have sunk into the machining grooves just enough... or somethin... lol. Looking at some pics of the crown, maybe I should do that too.
I haven't had time to take the thing apart again yet to see what is happening, although I probably could have in the time it took me to write this, lol, but I thought I'd give an update :)
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Oh ya, I did the tissue test and it passed.
Was just reading on how the shoulder on the pivot bolt could be too long also... jeepers.
Thanks again to all who reply, your input is helping me keep my sanity.. what's left of it :)
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Couple of things you need to do:
1.) LocTite, BLUE ONLY, will help, make sure you clean the threads on the screws and tapped holes before applying and let it sit 24 hours.
2.) That scope will not handle the recoil and will cause you problems, Get one of these: https://www.amazon.com/dp/B0099XIJKC/ref=wl_it_dp_o_pd_nS_ttl?_encoding=UTF8&colid=30PBNUOR2JYBY&coliid=I1VORNTZPY54DL (https://www.amazon.com/dp/B0099XIJKC/ref=wl_it_dp_o_pd_nS_ttl?_encoding=UTF8&colid=30PBNUOR2JYBY&coliid=I1VORNTZPY54DL)
3.) Read this thread: http://www.gatewaytoairguns.org/GTA/index.php?topic=51555.0, (http://www.gatewaytoairguns.org/GTA/index.php?topic=51555.0,) it goes over all of the beginner stuff that everyone needs to know about a springer from cleaning and setup to hold and shooting practices..
4.) Your initial seal probably failed due to over lubrication causing detonation, put some Moly behind the seal but not in front of it, if you pull it apart and your have soot there you are dieseling. You may need to clean out the old lube again.
5.) Pivot washers, get some M8 brass washers from your local hardware store, they should be easier to find up there than down here. use a little bit of Moly on both sides of the washers when you install them.
6.) when you tighten the pivot bolt hold the action vertical and the barrel horizontal, the barrel should drift down slowly of it's own weight, if it falls you have it to loose, if it just stays there you have it to tight.
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Haha, cool! Found my old thread!!