The request was made in the "Back Room" forumhttp://www.gatewaytoairguns.com/airguns/forums/thread-view.asp?tid=10139&mid=76156#M76152Here it is......... the page from the earlier website prior to the update.First, a little info regarding advertised velocities. I get many e-mails about velocities such as….
Bob… I bought a Gamo xx pellet gun and they claim that the velocity is 1000 fps and it is only shooting at 870-890 fps using Gamo Hunter .177 pellets (more or less depending on the pellet and pellet weight). What is wrong with my gun???
My response would be:If you look closely, many of the advertised velocities claim “Up to 1000 fps” or what ever. There is probably nothing wrong with your gun and that is pretty much a normal velocity for that gun using that pellet and pellet weight.
It is important to understand that when they do their promotional advertising and testing, they use very light pellets usually weighing 6 gr or less, sometimes as little as 5 gr. Using pellets that light will usually provide the advertised/claimed velocities. However, when using a “standard” weight pellet of say 7.9 to 8.3 or maybe even heavier, the velocity drops dramatically. That is to be expected.
Now for just a bit of info regarding the different pellets and their use.I suggest that you do not use light pellets in your gun. Shooting light pellets can be very hard on you gun internally, hard on the spring and seal and usually cause the gun to shoot very harshly. It can be almost like dry firing your springer when really light pellets like PBA’s are used.
By the same token, do not use heavy pellets in your gun. Although heavy (or light weight pellets) such as the Kodiaks will not damage Co2, PCP, and Pumper type airguns, they can and will sometimes cause severe damage to the main spring in Springer Guns. They can cause damage and detonation. This can and will cause spring fatigue and spring destruction beginning with just a few shots and when disassembled, the damage caused by heavy pellets and detonation is easily detected and identifiable. The spring failure is not the fault of the spring but spring abuse.Use heavy pellets at your own risk and expense.
For the longevity of your spring gun:
My suggestions are for .177 caliber gun that the minimum pellet weight should be 6.9 and the maximum pellet weight should be 9 grains.
My suggestions are for .22 caliber gun that the minimum pellet weight should be about 13.5 and the maximum pellet weight should be about 15 grains.
Why a Springer airgun tune?It is important to understand that tuning a gun does not necessarily increase the fps (and usually doesn't) unless there are issues such as a broken or fatigued spring, a damaged seal, or a rough chamber wall or a combination of those conditions and others. The logic in a tune is to extract the efficiency of the gun, to make it a smoother, more accurate, with more consistency and efficient with less spring vibration and twang and reduced recoil with an improved smoother and lighter trigger pull making it a more pleasurable shooting gun.
What a tune does and why it's important, whether I do it or someone else does it.
First: I have yet to see any lower end guns, especially in the Chinese rifle’s using synthetic seals not having at least some damage, often times minor, and some with sever damage, which the buyer will never know even while shooting it unless it is extremely bad or he breaks a spring or he has a Chrony and can see the power loss. Secondly: again, especially in the Chinese clones, the vibration or spring twang and torque caused by poor or incorrect lubrication, and poor quality control, rough components, and poor spring design and construction causes’ inconsistency, loss of power and inaccuracy. Thirdly: either little or no lubrication, or incorrect lubrication of other critical internal parts. Fourth: smoother, softer, and depending on the gun, shorter more predictable trigger pull, and finally, resolves most rough cocking conditions.
Spring twang or vibration and cocking roughness.
First there is the roughly finished metal on the interior parts caused by poor machining and stamping. Two dynamic things that happen when you pull the Springer trigger. First there is double recoil. When the seer releases the spring, the gun starts to recoil to the rear. Then when the piston hits the bottom of the cylinder, it drives the gun forward. The second thing is that as the gun is cocked, the spring expands and at the same time twists slowly until the piston is latched by the sear. It may also cant or bend the spring during this process. When fired, the reverse happens, but in a fraction of a second. The twisting during decompression causes the rifle to twist in the opposite direction of the twist of the spring. For every action, there is an opposite reaction of course. A tune helps reduce much of this violent reaction.
Tuning, if done correctly and depending on what kind of tune, reduces spring vibration or twang, increases power, and makes for a smoother cocking operation. In addition, there will also be a softer more predictable trigger pull if a trigger tune is done or the GRT-III trigger is installed (a far superior trigger with a lot lighter trigger pull).
Another important result is far less recoil, less twist (torque), more consistent, and will be more accurate shot after shot requiring very little service (lubing and maintenance) for the life of the gun.
Keep in mind though, springs do break on occasion and seals do go bad and are considered a where and tear item. I use nothing but the best seals and springs available for the particular gun. The best $30 for basic parts you'll ever spend on a Springer. If special kits are used, such as a TurboTune kit, or the GRT-III is installed, the cost will be a little more.
About the proper internal lubrication.
Proper lubing is of the utmost importance. How it is lubed, at what points it is lubed and what lube is used on those points make a tremendous difference how your gun behaves, its accuracy, it’s consistency, seal and spring life, and it’s longevity. It’s important to know that there are several lubes used in airguns for different purposes in different locations and they all play different roles.
So many things are resolved by a good tune and these principles apply to all airguns. You just can't beat the money spent for a tune, especially if it's tuned properly.
But please keep in mind, no two guns are the same coming off the line, or tuned by the same tuner, have the same power and consistency. Secondly, power should not be the primary concern, although important. If it's tuned and comes out extra strong, that’s fine as long as it fires smooth and is consistent. If not, it should be “de-tuned” a little.
I am especially fond of the Gamo series airguns and I further firmly believe that for the money they are some of the best guns to buy for the dollar spent. Best bang for the buck. The next choice is the B-20/26, and the B21/30. The real value though is that you can TurboTune them and wind up with a gun that will shoot as well as some $500-$600 guns, for a third of the cost. They don't all turn out to be monsters, but most turn out real well.
In addition to my well known SuperTune, I also provide the TurboTune for those who want the ultimate tune and performance.
| 19 Point SuperTune
includes Before & After testing |
|
Pre testing
Cleaning
Complete deburring
Honing & hatching the cylinder
Install new custom seal
Install new custom spring
Finishing the spring ends
Cleaning & lube trigger assy
Seer finish & polishing
Cocking shoe finishing
|
Polishing tophat (if applicable)
Heavy or Velocity tar
Molylube
Disassemble, clean & lube
pivot locking assembly
Bore cleaned
Check the crown
Adjust the pivot locking
assembly
External Lube
Final testing |
LocTite the mounting screws when final testing is complete on both services if requested.
Rem-Oil the entire gun prior to shipping unless otherwise requested
Note: New guns out of the box will be test fired but may not receive a 1st chrony test because it usually provides inaccurate results. Customers will receive a computer printout of all test results as well as a maintenance sheet.
Additions for TurboTune
I use a Maccari custom spring and Apex seal for the TurboTune. In the TurboTune, I machine the spring guides from scratch, fitted to your particular gun and main spring, as well as the spring seat and guide seat to the trigger block where applicable and can machine tophats and spring spacers.
I can do that because I have your gun in front of me for measurements and that of course usually can't be done with shelf parts. My TurboTune provides a better over all operation of the gun reducing vibration, twang and shock. Now your gun will shoot more consistently, provide longer spring life, reduce spring cant, and easier and smoother cocking. The TurboTune leads to further improved consistency and accuracy.
Depending on the type of piston, on some guns I also use stainless steel lower spring seats to help reduce spring torque reaction that causes the gun to rotate when fired. It’s an inexpensive worthwhile investment in your gun that will last for years and years.
Also another asked for or about info on tuning. That info is in the Library but also on my website. The is one on the B-19/Gamo and it's clones as well as a couple of others on the "Airgun info " page.
Charlie's Airgun Info Page
