Importance Of cocking effort in air rifles

[targetpoint]

I have searched all the topic in our forum to get some information on cocking effort in break barrel air rifles but alas there is very mearge information on it.I read the post by Mr Bennedose sir about the "spring paradox" very interesting and educative.Actually while searching through internet I was astonished to find that air rifles are categorized on basis of cocking effort especially the break barrels.More astonishing to me was to learn that more the cocking effort more is the power.Contrarily till now while tuning we try to reduce the cocking effort to get easy cocking for smooth firing cycle.Now from Mr Bennedose post we came to know that while his gun was tuned by a local gunsmith it had huge cocking effort but its velocity was poor but as he removed some coils cocking effort reduced but velocity increased.Actually the more I am gathering knowledge on cocking effort the more confusing it is becoming to me.So I am requesting our respected seniors and learned members to put some light on this topic so that new members like me get clear knowledge on cocking effort.So my questions are-1 Whether cocking effort is index of power in break barrel air rifles? 2-While buying a new break barrel should we estimate its power by its cocking effort.3-Does cocking effort depends on length of spring or thickness of its wire or on both?.4-Is there any optimum cocking effort for each and every air rile?

[bennedose]

targetpoint I think there are a lot of myths going around about cocking effort. In fact the book that a couple of IFGians kidnly sent to me as pdf (Air gun from muzzle to target) is very educative.

Fact is "cocking effort" is the most useless parameter for judging an air rifle's power. Cocking uses a lever action - and a basic principle is the longer the lever the lesser the work (but greater the movement). I can lift one end of a Maruti 800 using an 8 foot pole as lever. But if I give you a 4 foot pole and ask you do do it - you may fail and I will claim falsely that I am stronger.

So if I hold my Orion in mid barrel and cock it, I have to put in more effort than if I hold it near the muzzle. Secondly - I have an old air rifle that I respringed with a deadly heavy spring. Its barrel is longer than the Orion barrel but its cocking effort is so great that I can barely cock it if I hold it mid barrel. The effort required is far more than that for the Orion. I can only cock it by holding beyond the foresight. Yet - this is a useless air rifle that barely produces 400 fps/120-130 m/sec. (It has no rifling and is also inaccurate)

Every now and again I read someone's post on IFG saying that he will put a "more powerful spring". More powerful springs causing greater cocking effort do not necessarily translate into better power. There are too many variables. Two things that can increase power are things that are not easy to implement. If you can have a larger diameter receiver with a larger diameter piston, then you can expect more power. The other thing is that in some ill designed air rifles - I think cutting the barrel shorter might increase power - but this is obviously a risky thing to experiment with. You can finish off the rifle's usefulness by doing that.

In firearms the bullet is continuously accelerated right until the bullet leaves the barrel. In springers (but not in PCP) the piston actually compresses air so fast that the pistion almost stops just a couple of mm before hitting the end of the receiver. The compressed air then keeps expanding as it pushes the pellet out and as air expands its pressure drops. Depending on several variables the pellet may actually reach its maximum speed before it reaches the end of the barrel and it may slow down a bit before it goes out of the barrel. That is why you find a Precihole "Karbin" with shorter barrel and no loss of velocity compared to the longer barrel.

The following is my experience, based on information gained from Brihaji and by some reading and experimentation
1. About 30 to 32 coils of spring seem to be the best length.
2. If you get a 35 or 38 coil spring, it is better to "break in" the spring at full length. It will become shorter with use, after you have shot the rifle 50-100 times. After that if you are not satisfied with the power, cut the spring down to about 31-32 coils and try again. I have found a useful increase in power by doing that. Cutting the spring further may only decrease power. Do not cut a new spring that has not been broken in.
3. Among springs you will find that if the thickness of the coil metal is more the spring is more powerful. If the spring diameter is smaller, it will seem to produce more cocking effort but it may still not produce as much spring power as a spring of larger diameter.
4. A mad increase in spring power and cocking effort will not necesarily give you the best results in air rifle power.
5. Don't even think about cocking effort - curse the rifle that has a great cocking effort. it may not be the most powerful rifle.

[brihacharan]

Hi targetpoint / bennedose,
> Very interesting observation & analysis you got there....
> Even reputed Air Gun Gurus the world over are yet to pin-point the relationship between 'Cocking Effort' & Power/Velocity / Accuracy etc. because every individual AR comes with a built-in 'idiosyncrasy' - yet to be understood
> The true cocking power required to compress a spring can only be established by a mechanical device that records the effort required through a gauge...
> Physical effort which depends on the individual's strength & using leverage especially with the help of a muzzle break which extends the barrel length are not true tests to arrive at the exact pressure required...
> Besides there are too many variables that determine the characteristics of a spring....
1. Length / number of coils
2. Wire dia
3. Metallurgical composition
4. Coatings
5. Tempering / annealing for its resilience
6. Friction from the seal at the piston head
7. Breech seal
> Add to this one has to consider the 'swept volume' & size of the transfer port which also play an important part in the delivery of velocity & power....
> All these contribute individually or collectively to the performance of an Air Rifle...
> No wonder that 'each air rifle' (even though of the same brand & from the same batch) behaves in its own characteristic way....
> In the final analysis an Air Rifle (eg. 0.22cal) that shoots consistently anywhere between 600 & 650 fps with 14gr pellets & repeatedly gives 1/4" inch groups at 25 yards is the ideal AR one can possess & enjoy shooting it till kingdom come
Briha

[targetpoint]

What respected Mr Brihaji and Mr Bennedose sir has stated following points are clear 1-Cocking effort cannot be a basis of guessing power in air fifles.2-Cocking effort depends on character of spring.3-30 to 32 coils should be the max number of coils in spring.4-Cocking effort can be and should be reduced by proper tuning.I am thankful to both of you.

[Basu]

Dear Targetpoint,
You raised a very complex issue which was only addressed by Gerald Cadrew.
There are some observations I have which says that FPS is not directly proportional to spring power.
Light pellets love low power spring and heavy ones high power .
There are ample of evidence to show that when hard spring is used ,velocity went down instead of going up.
When I tuned my gun with low power spring ,the velocity of Aimco 11.3 gns went up from 550 to 575 but MSRH came down from 480 to 450 fps.
There is a particular corelation between spring power ,piston weight , size of transfer port and weight and shape of pellet which dictate the optimun transformation of potential energy into kinetic.

Basu