gamo losing power

[bowieshum]

hey, folks, i have a varmin hunter, after about 800 shot, i found that it loss about 20% of the power.
i used to able to put a hole on a license plate, but now all it do is put a big dent on it.
can anyone help?
i did clean the gun, and it is still the same.
i also tried the tissue test. and nothing.

[Gene_SC]

You may have a broken spring,,:(

[gamo2hammerli]

Or a cracked pistol seal....so air may be escaping through the back/middle of the receiver and not at the breech seal (If that's where you checked with the tissue).

[shadow]

A chrony would give you a real good idea of what she's pushing as far as FPS. Do you notice any unusual main spring noise when cocking or shooting it? the spring's have been known to break and the shooter will still function. Any sign of dieseling/smoke coming from the barrel after a shot? Sometimes on assembly at the plant the piston seal get's cut or nicked when installed which will cause a loss of power also. Cleaning the barrel won't make a difference in power but will effect accuracy and it's good to clean the barrel when you first receive the shooter then later down the road if the accuracy go's away, the lead help's season the barrel. I'm sure some more of the family here will jump in with some good idea's and we can get her fixed up for you. Also WELCOME! to the GTA family, lot's of real good family here along with ton's of info and knowledge. Ed

[mthomas]

you can verify a loss in power wih chairgun. look at where the poi at 50 yards should be for a given zero, then look at where yours is at, and alter the muzzle velocity in the calculater untill you find the 50 yard poi that you are achieving. Poor mans chrony.

Being a gamo, it will have been assembled very slopily, there will be excess lube all over everything. I bet your airgun currently or used to diesel almost every shoot (wisp of white smoke).Eventualy this causes something to break. You should rebuild it yourself, it is fairly simple. An easy source for parts is rich in mich(google to locate). He will send you a kit with all necessary parts and lubes. You will be amazed at the change in the noise,smoothness, and feel of the gun. do a little research on how to tune while waiting for kit to show up. A basic tune is pretty easy, just be thurough with th deburring, and build a simple compressor for the spring.

Alternatly, send it off to a tuner. Choose someone with a rep for quick turnaround, and who does not despise gamos. Gene would be a good choice.

[airgunandy]

Could it be the excess lube from the factory had finally burned off and now the gun has settled down to it's "normal" power level?
Just a thought.

[longislandhunter]

Moved your post to the GAMO GATE.....

Jeff

[mthomas]

no. gamo misstates their fps. try the chairgun idea to assess fps, it will give you a good approximation of fps. It is worth tuning the gun as it will be so much nicer to shoot.

[bowieshum]

thanks guys, will try every suggest here.
will let you guys know what happen next.

[xschug3]

bowieshum, I had the same problem with my Big Cat. I noticed that after approx 1500 shots I had lost significant power. I was beginning to get worried. I bought some new breech seals from GAMO and installed a new one. That seemed to help a bit, but definitely didn't take care of the problem completely. I remembered that I had never cleaned the barrel of gun since I got it. So, I used the trimmer line Goo Gone technique and immediately afterwards noticed significant results. I don't have a chrony but I would guess my fps increased by 150-200! I was very suprised, but I guess it makes sense. I have tried numerous different pellets and I suppose the buildup of lead had slowed down the original velocity.