GTA
Airguns by Make and Model => Gamo Airguns => Topic started by: ColdTexan on December 10, 2017, 10:49:34 AM
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So, I bought a Gamo ACCU .177. Love the gun! I have about 150 pellets thru it and it won't quit deiseling.
Anyone know how many pellets I am going to have to shoot before it will quit?
Anything I should do (that don't require breaking the gun down and cleaning it)?
Thank You for any help you can give me!
One COLD Texan!
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It should be setteling in soon, What weight pellets are you shooting, if less than 9.5 grain they may also cause sonic crack.
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I started shooting the JSB 7.3 grain and it was grouping VERY well. It was only going subsonic once in a while.
I have switched to the JSB heavy pellets last night, it seams like it is worse than when I first started. I cleaned the barrel last night when I finished shooting, I hope it will help today. The patches were black.
Thank You for the reply Back_Roads
Cold Texan
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My experience with a Gamo CFX, which is the same as an Accu, was that the dieseling did not stop until the grease was cleaned out and the thing and it was properly lubricated. Out of the box there was far too much grease in it. The dieseling broke the spring before I learned. Properly lubricated and with a bit of titivation you will have a good gun.
I found JSB 8.44 gn pellets to be the best for my gun.
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Thank You for the reply Novagun.
I don't know how to completely disassemble this rifle but I will take the stock off and inspect the chamber. If there is a lot of grease I can get to, I will clean what I can reach.
How is it that the grease on the spring is getting in front of the seal to make the gun diesel?
Cold Texan
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Here's how much grease mine had from the factory.
I think the grease is getting past the seal through those rips and tears in the seal caused by the factory shoving the piston assembly into the tube without deburring all the sharp edges in the compression tube.
(https://photos.smugmug.com/photos/i-76d3fpS/0/7efea5e1/L/i-76d3fpS-L.jpg) (https://www.smugmug.com/gallery/n-Q9N2pc/i-76d3fpS/A)
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WOW! My gosh, I will have to fire hundreds of shots to ever HOPE to get that much grease out!
I better at least take the stock off tomorrow and see what I can. I don't have a spring compressor. I might have to build one.
Thanks (I think) LOL
Cold Texan
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You will need a spring compressor, I use a workshop sash cramp. If you can make a spring compressor you can deal with the gun. Your gun is not hard to pull apart. The best way to proceed would be to look at a Utube video. There just has to be one on the CFX. The rifle is just a simple piece of machinery so don't be timid, you won't stuff anything up but while you are at it replace the piston seal because you can put money on it that it was damaged in the factory assembly.
There is no need to take the rolling breach out but get all the grease out from behind it. Rags and a stick will do it. If you think it needs washing out with turpentine then maybe take the breach out because you don't want raw turps in there when you fire it. You could wash it out without removing the breach but I would blow it out with compressed air afterwards and allow time for any residual solvent to evaporate so there was no smell at all.
Getting the breach out and back in is a job that needs a lot of care but the worst that can happen is that you will wreck the o ring. A few cents to replace if you get it wrong, not the end of the world.
Re-grease using very very little grease just a light smear to stop rust, a very light smear.
If the spring twangs because of the lack of grease put a PTFE plastic wrap around the front end of the spring and assess if you need a new rear spring guide. (PTFE is a fancy name for a slice off a plastic milk jug.)
Welcome to the Gamo Accu/CFX world, the tinkering is worth it.
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Kevin,
If you are not comfortable with tearing the gun down you can message me and I will send you a quote on tuning the gun for you.
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Thank You Novagun and OleTomCat!
For many years I did equipment maintenance on restaurant equipment. I still have all my tools and the Lord knows I have delt with grease--LOL
I have decided I will build a spring compressor this week and take the gun down. I have watched a couple of YouTube videos about it and I really think it won't be a problem. It will give me a chance to sand down any burrs that I find and in the end, I will learn a lot more about springers.
OleTomCat, can you tell me where I can order a new seal and O ring?
Thank You again friends
Cold Texan
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I liked my Accu177 so much I picked up a used one in .22 when it became available. If it's even close to accurate, hold on to it. Both .177/.22 are getting hard to find, especially the 22. People don't often let them go.
The gun's power plant Is easy to disassemble. The Achilles heel is the rotating breech o'ring. There's a fair likelihood it is already nicked. This is one springer that requires extraordinary attention to deburring all machined edges in contact with the piston. What ever the piston/piston seal contacts coming out of the gun and going back in during a tune, the breech seal will certainly come into contact with. You will likely ruin the o'ring removing the rotating breech.
Look up some of my posts on the Accu. There are probably comments about a hardware store replacement for the o'ring. Otherwise you are going to have a hard time finding a Gamo spec replacement. I use either one of two o'rings that I've found online (O'ring Store) or locally that will work. Both of them make the breech tighter to open/close but they do make for a strong seal.
Get rid of the grease or you will have recurring detonation which will likely toast your seals. The breech seal (the one on the barrel face) is very hard to source, I've no local source for them. I think the Aussie'a have one available, maybe on EBay. You can try shimming it you have the capability.
Sleeve the piston, heat shrink the rear spring guide and there's no need for the "tar" it shipped with. A light lube is all that's required after sleeving to make the Accu a "thunk" springer.
A good Accu is a fifty yard gun. My .177 loves cheap Winchester HP's and round nose.
Have fun!
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Thank You Atrie.
I called Gamo and those people are CRAZY in the head! They want you to have a FFL to ship you a piston seal! Who ever heard of such a thing on a AIR RIFLE!
I have left a message with P.A. (where I bought it) and I hope they will be able to send me one.
Cold Texan
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I called Gamo and those people are CRAZY in the head! They want you to have a FFL to ship you a piston seal! Who ever heard of such a thing on a AIR RIFLE!
Welcome to our Brave New World.
25mm piston seal (Small Apex), or your choice of many others are easily available.
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ARH sells complete gamo kits. Correct me if I'm wrong OleTomCat but doesn't the TX200 seal work?
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I called Gamo and those people are CRAZY in the head! They want you to have a FFL to ship you a piston seal! Who ever heard of such a thing on a AIR RIFLE!
I have left a message with P.A. (where I bought it) and I hope they will be able to send me one.
Gamo's stupid policy is why I won't buy another Gamo product.
Get the piston seal from ARH and take the rotary breech to your local hardware store. A 1/16" thickness o-ring will fit on the rear. I like to get one that is slightly undersize so it has a little more tension to keep it in place when I insert it. I used a little silicone oil to get it in.
For the breech seal I used two o-rings that I stacked and glued together with superglue. Put one in the breech groove, add a small amount of super glue, add the second, and then compress the two o-rings together on a flat surface.
Also - take a look at where the barrel threads in the tube. Mine had a sharp edge that cut my original breech seal.
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If the seal in the front of the breech block is damaged, and it probably isn't, I have made them out of clear plastic pipe. You need to face them off in a lathe to get the ends perfectly square.
If you want a really nice shooting gun forget the Gamo seal. I would forget it anyway. Make up a plastic adapter for the dovetail button on the piston and substitute a 25 mm Weihrauch seal. They don't come off, they are softer and better than a Gamo seal. They make the rifle a sweet shooter. Bit more expensive than a Gamo seal.
If you really want Gamo parts they are readily available here, not too expensive and the postage to the USA will not break the bank. PM me if you like but be warned Christmas is coming and New Zealand shuts down for about two weeks.
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25 mm Weihrauch seal.
Interesting. Are you talking about the old style with the thin outer ring, or the newer style? What does it do for velocity?
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I want to Thank You all for your advise and information. I have decided to go ahead and tear the gun down tomorrow. I have all the makings of of a spring compressor and will get it built in the morning. I will inspect the seals and find replacements for what I need. In any case it might take a day or so for the gun to completely dry out after I clean the grease out of it.
I think this will be a exceptional shooter that's why I don't dare send it back. P.A. already has them out of stock again and I have no idea when I could ever hope to get my hands on another. Even if they did replace it I would most likely have the same problem. I got the gun at a really good price on a sale and it is worth the effort and the small expense of getting it right.
I will take some pictures with my phone and post my results as soon as I have it back together.
Thank You all for the sage advise and information. I am new here and I can see why there are so many members!
Cold Texan
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Ok,
The Main Piston Seal is a Gamo Tesla Seal from ARH:
http://www.airrifleheadquarters.com/catalog/item/251485/2325552.htm (http://www.airrifleheadquarters.com/catalog/item/251485/2325552.htm)
The Spring is an E3650 also from ARH, replace it while you have the gun apart:
http://www.airrifleheadquarters.com/catalog/item/251488/5414946.htm (http://www.airrifleheadquarters.com/catalog/item/251488/5414946.htm)
The rotating Breach seal is best to get from Custom Air Seals of Australia, you will probably need to take this out to clean up under the breach so better to have them and not need them then need them and not have them...
https://www.customairseals.com/product/gamo-cfx-cfr-royal-rotary-breech-seal/ (https://www.customairseals.com/product/gamo-cfx-cfr-royal-rotary-breech-seal/)
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Thanks for that info Al. I was having trouble finding that breach seal myself--I figured Custom Air Seals had it, but I couldn't quite remember their name and the eBay search wasn't hitting it.
My CFX dieseled for quite a long time. Only a few were "gunshots"; usually is was just smoke drifting from the muzzle after a shot and the smell of snuffed candles lingering. I still catch the smell now and then after 4,000 rounds, but I haven't seen smoke in ages and the worst of the dieseling was over by about 500 or 600 rounds. It's on my list to tear that rifle down and do a nice job on the seals and surfaces as I put it back together.
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David,
You need to get your Kiester down here and shoot with us....
Gentlemen remember when working on a Gamo with a rotary breach
DO NOT HONE THE AREA WHERE THE BREACH SITS, MAKE SURE IT IS IN THE GUN WHEN YOU RUN THE HONE UP THERE OR YOU WILL NEVER GET IT TO SEAL CORRECTLY AGAIN.....
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bhh, the Weihrauch seal has a thin parachute skirt. I cant tell you of velocity because I don't have a chrony. Whatever it is the velocity is it adequate because the accuracy is right up with my Weihrauch and I have taken rabbits out to 40 metres. A long shot for me. Velocity is a bit down from standard because I have shortened the spring a little but that has nothing to do with the seal.
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Well, it is noon here in South Dakota and I have had a eventful morning! Besides taking out the Trash I have built a spring compressor and managed to disassemble the ACCU.
Just as you told me it was FULL of grease. It was covered! I have found small nicks in the seal and in the breach seal (to the barrel) and the breach O ring. I have little doubt how the grease was finding it's way into the breach, I even found a "gob" of grease in the rotary breach.
I have parts on order. Meanwhile I have a lot of cleaning to do!
Thank You all again for your information!
Cold Texan
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Well, it is noon here in South Dakota and I have had a eventful morning! Besides taking out the Trash I have built a spring compressor and managed to disassemble the ACCU.
Just as you told me it was FULL of grease. It was covered! I have found small nicks in the seal and in the breach seal (to the barrel) and the breach O ring. I have little doubt how the grease was finding it's way into the breach, I even found a "gob" of grease in the rotary breach.
I have parts on order. Meanwhile I have a lot of cleaning to do!
Thank You all again for your information!
Cold Texan
I use Dawn dish soap and water, it will cut the grease...
Do some research on Ultimox or Krytox, expensive stuff but it is a one and done lube that will not diesel...
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About honing...personally I wouldn't bother, too much effort for questionable results. Mine do just fine without it. De-burring is where to spend the energy. You need small files, Jeweler, Swiss, so on. Good ones can get pricey.
Every slot or hole in that receiver/compression tube must be de'burred on the inside (where they are difficult to remove). Test with cheap cotton swabs, the dollar store type with loosely spun balls. A burr will snag the loose cotton warning you your work is not finished.
Installing the rotating breech is tricky. You really need to chamfer/bevel the under side of the leading edges of the slots/holes. What will happen is the thin, compressed o'ring will squeeze out as it passes the opening. That is when the tear most likely occurs.
I have a tiny flat edge screwdriver that I intentionally dulled and rounded the edges of so I can coax the o'ring back into the hole while pushing the lubed (Krytox) o'ring and breech slowly forward with a wooden dowel.
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Thanks for the info, Novagun.
Cold Texan - Deburr every edge in the tube and put it away for the evening. Next day come back and go over it again for anything you might have missed. I find that I do a better job that way.
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David,
You need to get your Kiester down here and shoot with us....
I'd like to, but it's 200 miles one way! Not impossible, as I've done overnight trips to Charleston, but it would take some planning ahead to make sure other things don't take priority. The key would be to plan the next trip to the area around one of the weekends you guys will be out :). Does the day vary or is it something like always the 2nd Saturday of the month?
By the way, thanks for the heads up on honing only the piston area--I'll remember that when I get into my CFX.
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David,
You need to get your Kiester down here and shoot with us....
I'd like to, but it's 200 miles one way! Not impossible, as I've done overnight trips to Charleston, but it would take some planning ahead to make sure other things don't take priority. The key would be to plan the next trip to the area around one of the weekends you guys will be out :). Does the day vary or is it something like always the 2nd Saturday of the month?
By the way, thanks for the heads up on honing only the piston area--I'll remember that when I get into my CFX.
Always on Saturday usually the middle of the month, post in the thread on the SC state gate and you will see the dates, I usually put them at the top of each new page. We started with a fall classic this year around my B-Day in Oct, this will be a three day event going forward, I figured that would be the best time for guys coming from far off to make it here.
We have a Forum guy that lives in Simpsonville that makes it down about once every two or three months..
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Here is a update.
I ordered the parts (thank You again Al for telling where) and today I got the piston seal and the replacement spring. In the meantime I have everything de burred and looking good.
I had a look at the O rings that were available at the hardware and auto parts shops in my area and only found 1 that might work on the breach. I got my caliper out and found the O ring I really need is 1.5mm with a 25mm (OD) 22mm (ID). I found a place on the internet who sell O Rings and ordered 25 (they were so cheep I thought why not). So when I get them and check them out I will have a supply if anyone needs one.
I am still waiting on the parts from Down Under and the O Rings and the grease Al spoke of that will not diesel.
I am tempted to put this back together with what I have and shoot it a few days till the parts get here. I found that when I removed the breach seal (like a small piece of tubing) I could turn it over and it was fine. I think that the one O ring I bought at the hardware store would work even though it is a few hundredths smaller than the original.
It might be several weeks before I get it all and I have to admit I am tempted to go with what I have. The rifle is NEW, I had barley shot it before I had to tear it down and start the waiting.
This will be my first "tune" and I have learned a lot. I have to say even though it cost me a few bucks I think I will have a rifle that I will value more after having put this work into it.
Cold Texan
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Yes I would go with what you have got. Now you know that dismantling the gun is not a major engineering task and you can always do it again when the parts arrive.
If you are looking for a temporary piston seal you could try an engineering supply shop. I use ordinary hydraulic seals quite a lot. Sometimes re shaped or resized but often not. If I remember correctly 25 x 12 mm.
They are cheap and effective.
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Thanks Novagun.
I have the new seal, it looked way better than the seal that came with the gun! It is softer (green color) and I have it installed on the piston.
The only thing I am really waiting for is the O ring and the breach seal and the Ultimox grease (ordered from Amazon).
Cold Texan
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Have you degreased everything yet? If not you can put it back together and shoot, if you have it cleaned I would wait, it usually doesn't take that long for parts....
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Sounds like the new piston seal could be a good one. The Gamo seals are ok but I think they are too hard.
Gamos are fun and good to learn with. The bonus is they can shoot very well when you have finished the tutuing.
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Yes Al, there is not a SPECK of grease left on any part! LOL
De Greased, De Burred and what we call back home "Clean as a hounds tooth"
Your advise makes perfect sense; I am just inpatient.
In fact, I don't even know what grease I could get "over the counter" in the small town I live in that would work. I might have enough of the original grease on the towel I wiped everything off with before I cleaned it all.
However, you are right, I will wait at least until the Ultimox gets here.
Thank You Al for all your advise.
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In fact, I don't even know what grease I could get "over the counter" in the small town I live in that would work.
I've used white lithium grease before with no problems.
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OK friends and neighbors; The grease came in today and I finally was able to put it back together!
I have just finished a test run and the gun is shooting great! Not one diesel shot! Smoother than it was and with the new spring shooting just a few FPS slower (about 12).
It is DEAD ON accurate and a joy to shoot!
I want to thank you all again for your help! This was my first "tune" and I have learned a LOT. If I had it to do all over again I would have tuned the gun before I ever shot it the first time. I got the gun at a pretty good "cyber Monday" discount and the savings paid for the parts.
I hope you all have a Merry Christmas! We will be covered in snow and ice here but I will be shooting my air rifles in my basement.
The Cold Texan
Kevin
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That's great, Kevin. :D
Now to work on the trigger... ;)
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The GRTIV trigger is on my Accu.177 which was an improvement. I got another GRTIV for my Accu.22 but didn't care for it much.
I reverted to the SAT for the .22 but with a longer adjustment screw. With that setup the "1st" stage is long with slight spring pressure before light resistance of the 2nd stage let off. Definitely a target trigger only, no way I would hunt with it. I would like to add some more first stage resistance and lessen its length.
You may want to play with the SAT Gamo setup a bit before considering the GRT. Either way you will certainly enjoy the gun. I can say it is one springer, correction, two springers I will never regret buying. Congratulations on your choice.
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I thought I would add one more item of information to this thread in case someone at a later date is looking here for information.
The breach seal O Ring measurements are 25mm (OD) 22mm (ID) and 1.5 mm thick! I have extra of these O rings if you want to get in touch with me. I ordered 25 from the O Ring Store (google it)
The breach seal (where the barrel meets the breach) measurements are 9mm (OD) 6mm (ID) 1.5mm wall thickness with a height of 3mm. It looks for all the world like a piece of tubing. The replacement I ordered was red in color and pretty hard. I have not looked for it yet on the net but I expect 9mm tubing could be bought on the internet. 6 inches would make a BUNCH of these seals.
I have already said that I got the replacement spring and piston seal from Air Rifle Headquarters for about $30. I bought the grease I used (Ultimox) from Amazon. I think it cost about $12. You can order the breach O Ring and the Breach seal from a place in Australia called custom Airseals for $14 US. If you order them expect a several week wait.
Cold Texan
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The 25 mm o ring you mention are a standard engineering part here available from SIL. (Seal Imports Ltd) by the handful.
They are pretty cheap but depending who you strike at the counter you may have to place an order for bits and pieces totaling $10. Otherwise
you could end up buying a very expensive o rong.
I am told that a great volume of seals are made in Turkey. Wouldn't put it past the Aussies to buy in bulk from Turkey and onsell to airgunners at a huge rip off margin. Be interesting to see what the American price is for say one and ten at a local engineering shop.
I had some Hatsan breach seals, three I think, made to special order a while ago by SIL. I think they were $12.00 each. Then I discovered it was really easy to make my own at about nothing pence each.
O rings would be a bit hard to make.