Springer Vibration-Richter or MMI Scale

[Basu]

Vibration in Springer is something that can not be ignored when it comes to shooting pleasure.
I have tried to reach at the relative datas to find out which is the maximum level of vibration that is tolerable in springers.
I have tested three of my guns whose details are as under :

SDB 45 Classic 0.22
Pellet- Aimco-11.6 grns-velocity-620 fps-vibration-5.2,5.3 richter
Pellet-MSRH- 14.0 grns- Velocity-490 Fps-Vibration-4.3 richter
Pellet-MSFH- 14.3 grns- Velocity…….. Fps-Vibration-4.4 richter

National 25 0.177
Pellet-MSFH- 7.71 grns-Velocity-550 fps-Vibration-3.8,4.00 richter
Pellet-Gsmith Hiimpt-10.4 grns-Velocity- 460 fps-Vibration 2.2,2.8 richter

Local 35 0.177
Pellet-MSFH-7.71 grns-Velocity-740 fps-vibration-4.00,4.2 richter
Pellet-Gsmith Hiimpt 10.4 grns-velocity-640 fps-Vibration- 4.00 richter
Pellet- GSametur-8.4 grns-Velocity-710 fps-Vibration-4.1 richter

Out of the above three guns , the N-25, nicely tuned, gives me the highest shooting pleasure.
Even though SDB45 delivers highest vibration, yet I love shooting this gun.
My Local 35 is most powerful with TTI 39 coil spring, highly tuned and gives lesser vibration but due to its buzz I find it uncomfortable.
I have this feeling that a vibration less than 4.00 richter is the best for shooting pleasure and one can continue the same till it reaches 4.5. Beyond that it becomes a little uncomfortable.
The testing was done with an android application called “Vibrometer” can be easily downloaded from
Play stores.
I put the gun horizontally on the floor and placed two boxes of MSFH pellet box just below the gun so that it can move easily and then kept the android phone on wood at receiver then pulled the trigger.
I request you to give feedback about your reading regarding tolerable vibration level of springers.
This application takes into account transverse vibration also.

All FPS datas are of Cronoconnect tab2.

Basu

[mercury]

I find it interesting that the lighter weight pellet gives a higher reading....more vibration. any reason for that??

yes the N25 does give the lowest reading but a noticeable variation. so , is there a difference in accuracy between the pellets? the 35 is surprisingly very consistent with all pellet weights....would that imply that the 35 is not pellet fussy and groups well with all three pellets?

[brihacharan]

Hi Basu,
> Very interesting experiment
> Somehow I favour the SDB 45 with its 4.00 to 4.5 Richter reading...
> As both you & Mercury observed lighter pellets especially 0.177 cal reading is a shade more in comparison with o.22 cal.
> Remember that many parameters are responsible for the variations in the reading such as:
1. Fitment of the pellet in the breech
2. The efficacy of the breech seal to arrest air leak
3. Probable dieseling due to remanants of lube in the receiver
4. The condition of the seal on the piston (soft / hard / dry / moist etc)
> Nevertheless the observations are truly thought provoking - Great work Basu
Briha

[bennedose]

Thanks basu for giving me something new to play with. I have always wondered why my old (but tuned) SDB 50 with its less than satisfactory sights still attracts me for plinking pleasure over and above the far more powerful Orion and IHP 35.

[bennedose]

Basu I am facing several problems:

1. I am unable to find any Android program that actually makes a record of the highest vibration sdetected. All have a moving display where the reading vanished beyond the screen edge in less then one second
2. By placing my rifle horizontal on the floor without any restriction I find that the recoil effect is variable because my finger has to be on the trigger to fire and that actually moves the rifle back by a variable degree depending on trigger sensitivity

I am thinking of fixing the rifle to a vise and then recording vibrations - but first I need to get software that displays a record of maximum vibration rather than a moving graph. Vibrometer (or the other three programs I downloaded) do not do that.

[brihacharan]

Basu I am facing several problems:

1. I am unable to find any Android program that actually makes a record of the highest vibration sdetected. All have a moving display where the reading vanished beyond the screen edge in less then one second
2. By placing my rifle horizontal on the floor without any restriction I find that the recoil effect is variable because my finger has to be on the trigger to fire and that actually moves the rifle back by a variable degree depending on trigger sensitivity

I am thinking of fixing the rifle to a vise and then recording vibrations - but first I need to get software that displays a record of maximum vibration rather than a moving graph. Vibrometer (or the other three programs I downloaded) do not do that.

Bennedose wrote....
I am thinking of fixing the rifle to a vise and then recording vibrations
By doing this I'm afraid that the "Vibrations" will be absorbed by the 'Vise' & as such would not relay the exact vibration quotient to the recording device
Briha

[bennedose]

Yes, that is true, but using the Vibrometer sotware you don't even need to shoot the rifle to detect "vibrations" All you have to do is simply shake the rifle and it will show "vibrations" in the reading. In my view that would make the readings nearly useless.

Not fixing the rifle at all will cause it to move by a variable amount depending on friction and an unknown amount of vibration energy is lost in physical movement of the rifle. The vibration we measure will have to be what is detectable after all physical displacement of the rifle is arrested.

[brihacharan]

Yes, that is true, but using the Vibrometer sotware you don't even need to shoot the rifle to detect "vibrations" All you have to do is simply shake the rifle and it will show "vibrations" in the reading. In my view that would make the readings nearly useless.

Not fixing the rifle at all will cause it to move by a variable amount depending on friction and an unknown amount of vibration energy is lost in physical movement of the rifle. The vibration we measure will have to be what is detectable after all physical displacement of the rifle is arrested.

>Bang on Bennedose
> My random thought - Can the AR be wired to an 'Oscilloscope' to record the vibration & compare the reading with a 'Standard Vibration Table'???
> I recall doing some experiments with a 'Tuning Fork' during my physics lab(college)assignments to record vibrations
> I'm sure pocket size / hand held devices must be available that record vibrations - Just like the ones that's used to record velocity in ARs.
Briha

[Basu]

Dear benne,
Just keep the loaded gun on the floor on support of 2 match boxes or so.
Put the mobile on the wood near receiver,then start the application and softly pull the trigger.
There would be graphic spikes as firing takes place.
Ignore the spikes , just read the maximum numerical reading on the top of the screen.
Every time you test , theapplication has to be restarted.
It is very easy to operate.

Basu

[bennedose]

I modified the set up for this test in several ways. I fixed a vise to a board, fixed the rifle in the vise and and weighed the board down so that it would not move with recoil but merely vibrate/jerk. I decided not to put my phone in contact with the rifle which has already damaged a scope with its vibration. I also felt that if the phone was jumping about then that would affect the accuracy of the reading. So I fixed the phone firmly (using duct tape) to the same board that the vise/rifle was fixed. The photo below is an image of the set up - but the phone was needed to take the photo so the phone is represented in the photo by a piece of paper marked as "phone"

https://docs.google.com/file/d/0B3JNY4I ... sp=sharing

I conducted the test with 3 rifles but only AIMCO round pellets. I got somewhat variable results:
SDB 50 - 6.2 to 6.8 Richter (150 m/sec)
IHP 35 - 6.5 to 7.5 Richter (190 m/sec)
Orion - 7.8 to 8 Richter (200 m/sec)

The variable readings could be because the rifle was not fixed at exactly the same spot in relation to its center of mass each time it was cocked, but definitely the high values are higher in the rifles that generate more power and low values are lower in the rifles that generate less power. So yes - I think you have come up with an interesting discovery. After all the Richter scale is a logarithmic scale meaning that 7 is ten times more than 6, and 8 is ten times more than 7, and 100 times more than 6.

But when I thought about why the SDB is enjoyable for plinking - I think it is not the vibration. The barrel is longer and the spring easier to compress (shortened/cut Cherokee spring) and the trigger has become very smooth compared even to the Orion and IHP. Those are the factors that add to plinking pleasure. The orion and IHP require a lot more cocking effort with their shorter barrels.

[brihacharan]

But when I thought about why the SDB is enjoyable for plinking - I think it is not the vibration. The barrel is longer and the spring easier to compress (shortened/cut Cherokee spring) and the trigger has become very smooth compared even to the Orion and IHP. Those are the factors that add to plinking pleasure.
The orion and IHP require a lot more cocking effort with their shorter barrels.

> This could perhaps be overcome to an extent by fixing a 'Muzzle Break' ....
1. Will give leverage during cocking to make the process easier
2. Improve barrel harmonics - could reduce vibration (lower richter reading)
Briha

[brihacharan]

Vibration in Air Rifles

Air Guns by & large are mass produced which result in some weak links which need some improvement to make them perform smoothly when fired. While some gun makers use good quality springs others use hardened wires because "power crazy air-gunners" want high velocities.

Air guns in UK and India are designed to operate at 12ftlbs, however it is possible by tuning them one can probably get 50-70fps more than an out of box factory made gun.

Remember the basic law of physics – Vibration occurs when ‘potential energy is converted to kinetic energy’ (potential energy is when the air gun is cocked – while kinetic energy happens when the engagement of the piston sear & trigger sear is released making the piston to move forward with force)
Now it’s the quantum of vibration that determines the smoothness in performance of an air rifle. Excess vibration can also result in the loss of accuracy.

THE REASONS ARE:
•In some air guns because of poor tolerance while machining their parts result in excessive friction which turn worse due to lack of lube. However these areas can be re-machined or fitted with thrust bearings or buttons to eliminate the problem.

•Buttons are usually made of a synthetic material called DELRIN that are inserted into the holes machined on the piston to perfectly match a honed receiver.

•Proper lubrication is an important element in a gun performing smoothly and also help it last longer. Take care not to over lubricate as excess lube in the compression chamber will burn seals & cause dieseling that will shorten the life of the spring. A spring that is lubed with excess heavy grease will result in wide velocity changes initially and also affect accuracy initially till the gun settles in after a few hundred shots.

•It’s very important to ensure that the fitment & quality of the breech seal is perfect in every respect. An improper fitment can cause leakage of air which will affect the air gun’s performance and accuracy. Making sure the air rifle is sealing correctly is the single most vital aspect.

•Besides all this, selecting the right spring, seals and lube means nothing if the compression tube does not conform to its designed specifications. In the case of a receiver whose ID is irregular, honing the internals with a precision honing tool will eliminate this problem. Finally see that the size of the transfer port conforms to specifications, it should neither be over-sized nor undersized.

•Eliminating vibration is to ensure that everything part is precisely fitted in the air rifle including getting your air rifle’s stock screws firmly in place.

Tuning is a highly involved & precise process where adherence to size specifications of all components is both critical & crucial. Naturally a finely / perfectly tuned air gun is a joy to shoot -smoothness & consistent accuracy shot after shot!!!

Briha

[mercury]

Bennedose , it would be interesting if you could find a way to get readings of the vibration on the barrel....barrel harmonics , as Briha rightly calls it...in comparison to the vibration on the power plant. there was a video posted here a while back , showing in slow motion the vibration on an air gun barrel....amazing how the barrel moves , like waves. so watch the phone !!

Briha , agree with you. even some thing as simple.... and often overlooked....as having the right torque on the stock screws can make a difference. there is also the human element that can help in controlling this vibration.

a consistent hold....... when we hold the gun differently every time we shoot it, we are changing the entire shooting / vibration process.

work on the artillery hold......let the gun vibrate on its own and not alter the vibration with a tight grip / tucked tight to the shoulder.

follow through.....keep sights on target till the entire vibration process ceases.

on a different note.....taking an average of Bennedose and Basu's post.....we have a reading of around 5 on the Richter scale . is it "THE RICHTER SCALE " , now , that's like a major earth quake every time I take a shot with my air gun....an air gun really !! wonder what it is on a PB ??

[brihacharan]

Mercury wrote....
On a different note.....taking an average of Bennedose and Basu's post.....we have a reading of around 5 on the Richter scale . Is it "THE RICHTER SCALE " , now ,
That's like a major earth quake every time I take a shot with my air gun....an air gun really !! Wonder what it is on a PB ??

Briha

[bennedose]

Mercury wrote....
On a different note.....taking an average of Bennedose and Basu's post.....we have a reading of around 5 on the Richter scale . Is it "THE RICHTER SCALE " , now ,
That's like a major earth quake every time I take a shot with my air gun....an air gun really !! Wonder what it is on a PB ??

Briha

Each air rifle (weighing approx 3.5 kg) was mounted by me on a set up of a total weight exceeding 10 kgs. Still, the entire jing bang lot would jump every time I shot a pellet (and so would the phone before I fixed it with duct tape.) I am glad I did not fix the phone directly to the rifle stock or butt.
If the rifle can make a 12 kg weight jump 2 cm, then it can make a 70 kg man jump enough to kill his aim if he resists. So I suppose mercury is perfectly correct in asking if barrel vibration can be measured because "aiming and shooting" is all about letting the rifle vibrate as much as it wants so long as it remains true for those nanoseconds while the pellet leaves the barrel.

I suspect that the pellet itself leaves the barrel a split second before the piston hits the end of the chamber so the "reverse recoil" may just cause vibration but not affect the aim.