Just got my CFX from CDT today.

Cocking my cfx for the first time felt very smooth. I shot only a few after work since it was dark out. This cfx will probably get shot over the weekend, hopefully on some squirrels. As for the Chrony and Trigger Test Data:
Turbo Tuned.
Gun Tested : Gamo CFX .177
Brand Pellet: Gamo hunter 8.3 gr

Trigger pull weight: average pull Post Mod 1 lbs 10 oz

My CFX I sent out to CDT is pretty much brand new. The only mod was the GTX trigger install. One prob it did have was that fact that the factory seal was loose, prob because it was a display model and the public opened the breech w/o cocking the rifle afew times. I sent it out to CDT, he worked his magic on it but something puzzled me. Not owning a chrony, I never new what my velocity was. I assumed it was around 1000fps +/- 200fps depending on the pellet grain. But after I got my CDT print out, well.... it was extremely low. CDT did his magic and I am extremely satisfied with his work. My fps read:

Highest velocity : Pre-tune = 577, Post tune = 631
Lowest velocity : Pre-tune = 551, Post tune = 614

I have read and understood that my velocity may be a little low but as the seal breaks in and mates to the compression chamer it will increase, usually somewhere between 3-5%. That means when it is broken in, I would add like 30fps or less to my post tune number. Are all CFX' chronied this low? I was expecting to see atleast 800fps from my cfx. Here are some photos of my print out from CDT.



http://img.photobucket.com/albums/v172/KHIEM/charlie004.jpg

http://img.photobucket.com/albums/v172/KHIEM/charlie005.jpg

http://img.photobucket.com/albums/v172/KHIEM/charlie007.jpg

http://img.photobucket.com/albums/v172/KHIEM/charlie008.jpg

[-=ed]

my shadow supreme was the same pre-tune, and went to 660avg after the tune [new mas spring?]
It might get a bit faster, but with a 14g pellet, that's good enough for what I need.
For a cannon, I'm looking for a used Rws54.

[Gene_SC]

Glad you got your CFX back Khiem. With that trigger you should get very tight groups now. Ya it is funny about what you said about thinking you would get 1000 fps  + or- 200. Well Gamo and allot of other manufacturers advertise 1000 fps but do not tell you what pellet they use... Did you get a new spring and guide installed? When I sent my CFX .177 to CDT, I had him do a Turbo Super Tune which I think included a new spring, new hand made spring guide, GRT triggers, deburd, lubed and his magic touch...

I think my CFX .177 fps in in the high 800's to low 900's. I will show you my chrony results here at the end. One thing that is very important. Bob does not tune for high fps. He tunes for performance. The main thing is the deviation of fps between shots. The least amount of deviation the closer and more accurate is your groups. Consistancy is what I look for after each tune. And Bob has consistantly given me good deviation numbers on all my air guns after a major tune.

Looks like you have a winner there Khiem. Good Luck and happy hunting. And you are getting a good scope mount to boot..

Gene

[-=ed]

A shadow supreme is a .22, and going from 580 to 670 is pretty good with a 14g pellet

My S1k went from 880 to 965 with 7.9g pellet

both were much more consistant in speed.

Both had turbo with trigger...

Compare our CFX' both with turbo tunes, both using the same pellet, I dont understand why there is a great defecit between our cfx'.? Can anyone help explain please? :0

[Gene_SC]

Kiem, there is a difference in pellet wt between your tests and mine. That would make yours a bit slower in fps. If you look at my two CFX results you will notice that one has slower fps than the other. What I go by is the deviation. The lower the deviation the tighter the groups are when shooting or hunting. Consistancy is the key to a good springer when it comes down to daily shooting.

I can't explain why your CFX has slower fps than mine. It could be your CFX is an oldermodel. I am aware of internal design changes. That may be the reason. Gamo advertises 1000 fps but generally you can knock off 20 to 30 percent because they use the lightest pellets on earth to test them.

Gene

I will start that I am new to this and do not doubt about Charlies work AT ALL, but I can do the math.  With the post tune velocity's his CFX is only getting about 40% of the advertised speed and I understand they use lighter pellets and you should not expect that.  To me it seems that Kiem's assesment should be correct, that depending on pellet weight he should expect somewhere between 750 and low 900's, which is the 20% to 30% lower than advertised.  I had always read that when there was a a drop in 200 fps or so that you should start looking for something being wrong, and since everyone else's speeds were higher and we know Charlie has painstakingly tuned it, and that all the seals and such are in perfect working order so that leaves us with what?  It's a lemon?  maybe it will increase after it breaks in from the tune?  Did Charlie have any idea why or note that he thought it was low?  So I can understand you question Kiem, I would have the same one.  Thanks for sharing and I would love to know what you figure out.

[-=ed]

Perhaps your barrel is on the high-side of the diameter curve, and maybe you even got a box or two of pellets that are on the small side.

I threw out a tin of Gamo hunters whenmost all consistantly fit poorly in the breech.

Just a thought, but something is causing the problem, and CdT's ability to get the spring quiet and to deliver the most air seems pretty good to most of us who've used his services.

It may be one of those interesting problems that are not easy to track down, but there is help here.

[Gene_SC]

Well Peter, you have shed some lite on the situation. It is either a limon or something is not right. Maybe CDT will come back with some follow up.

Gene

[CharlieDaTuna]

and that is, not all CFX's are the same for sure. I believe the Gamo CFX is a very good gun but one of the things that seems to be unique about the CFX is there is a lot of variation in velocity from gun to gun as most of us know, especially in the .177's.

One of the main factors for this is it seems that the bore diameters do seem to be of a slightly larger diameter. (A loose fitting pellet in a bore can have a huge impact on velocity of course). This seems to be especially true of the newer CFX's  but was apparent in some of the earlier ones also. I don't know why that is and has been a subject discussed at length on some of the other forums in the past. The later CFX's with the serial number on the barrel do not have that problem.

 I almost  always use Gamo Hunters or Match pellets for pre-testing and post tune final testing. The reason being is that the Gamo Hunters or Match pellets seem to fit the chamber in most guns, and not just Gamo's,  better than other pellets. That is not to say that it is the best pellet for the gun, it just seems to fit the chambers better. But in almost all of the CFX's, they seem to just about fall into the loading port as does just about any other pellet that I have tried.  I'm sure that most of you that own CFX's are aware of that. Some pellets are so loose that they will just about fall through the bore. One thing that will help is DO NOT CLEAN THE BARREL and if you do, use only a dry patch.

Another thing that one needs to be aware of in the CFX is that after inserting a pellet into the loading port, it is very easy if the pellet is not completely inserted or the pellet skirt is distorted , to shear off  tiny bits of the skirt as the port is being rotated and these particles  can get between the rotating loading port cylinder and the barrel block and then gall the seal. This can also happen if  there is loose lead particles on the pellet that can be transferred to the mechanism.  If you are lucky, they may embed themselves  into the seal and not cause a problem but that's not likely at least long term. Eventually they will cause seal damage. Also, many lubes can also damage the seal so be careful what you use in this area.

The thing that is disturbing about this is that it can possibly happen the very first time that you insert a pellet in a brand new gun or the hundredth time or possibly maybe never if you are lucky. When it does happen you will not even be aware of it until you start losing velocity.

One other very important thing to keep in mind. DO NOT ROTATE THE LOADING BLOCK UNLESS THE GUN IS COCKED. The pressure against the rotating block by the main spring can destroy or damage the seal in a heartbeat if rotated uncocked.

With all of that being said, when I finish up a CFX, I never know what to expect in velocity with any certainty. The one that Gene has is a rare exception to the rule for sure. There are a few other like his but the velocity in them is usually not that high.

[-=ed]

It would certainly be nice to know why it shot so low to begin with, and why the new seal/spring didn't bring up the velocity more.

It makes me think that the problem would have to be in the barrel diameter, or something else that wasn't changed by the tune.

I would suggest you either go to JM's website and order a new seal http://www.airguns.citymax.com/catalog/item/251485/2325552.htm and spring http://www.airguns.citymax.com/catalog/item/251488/43410.htm, also remove the loading port once you have removed the spring and piston to make sure that the o'ring a 1mmx20mm that goes around it isn't torn or missing.  Another possibilty is email "rich from mich" peterdragin@comcast.net and he makes and sales complete home tune kits, guide, tophat, spring and seals, others have been real happy with his products, and his prices for his stuff is dirt cheap!

I have a cfx that I did my own tune on guide, seal, spring, and deburr and I am pushing kodiak heavies at 798fps avg. and RWS superdomes at 937fps avg. with a max of +/- 3 fps.


http://www.airguns.citymax.com/catalog/item/251485/2325552.htm
http://www.airguns.citymax.com/catalog/item/251488/43410.htm
peterdragin@comcast.net

I don't think I'd call it variations in Gamo performance....You should be seeing 800 fps at a bare minimum with a CFX in .177. Maybe you got a lemon, but then again, the tune should've fixed that. I hope you can find a way to get the problem remedied. Right now you've got an extremely weak and extremely expensive pea shooter. You can buy a croosman 760 from Walmart for $30 that does 600 fps.....................

Good luck getting the problem fixed.

Tim

[Gene_SC]

Hi Bill

Sounds like you are a shooter and tuner of your own air guns. It is nice that you are mechanically inclined enough to tune your own air guns. Some of us do not have the mechanical abillity to do these things. Some of let others do the tuning for us. If Khiem had tuned his own air gun do you think the CFX fps would of been any better? I personally do not tune my air guns. I let professional tuners like CDT, Mac 1 and Roy Weid from Mountain Air do the work for me because I do not know enough to tune an airgun. If I ran into some trouble, I would not know what to do. In addition, I do not have the tools it would take to do the job correctly.

I think that your tips are great on where to buy the parts. This is good for our forum members and I really appreciate your contributing the information. But like I said above, allot of us do not have the mechanical aptitude or the proper tools to do the tuning that the pros do.

With that said, I thank you for your input Personally I think that CDT would take back any air gun that he tuned if the client was unhappy with the results..

Gene

[Gene_SC]

Tim

I must say that you are very outspoken about the tuners warranty. Do you know CDT? Have you ever had a tune by CDT? CDT has been around a very long time and his work and reputation has been exceptional.
I think between Khiem and CDT they will work it out. Don't think they need any outside help.

Gene