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Understanding grain weights

Medwayman

Medwayman

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After seeing a youtube vid (which I can't find again) chap on there said you could have a legal rifle but with the wrong pellet still break the law, after a bit of research I got a lots of numbers!!!
a Layman's term explanation would be nice!!!. did find a conversion chart and put what I think right the numbers are in but I was getting odd numbers back.

My Rifle is 14.6 Ft-lbs (19.9 J) using pellets at 7.56 this means ????? as long as it is less than 20J I am fine.
 
You need both the pellet weight and the muzzle velocity for that pellet to work out the muzzle energy. I can’t remember the formula off hand but look up either the ChairGun or strelock apps. With both of those (or similar) you can enter in the variable and it will give you the energy of each given pellets as well as aim points at different ranges if you enter in further info (scope height, ballistic coefficient etc). They’re good programs to have a play about with although obviously the aim points will only ever be an approximation :)
 
Pyramid air also have a great tool for calculating muzzle energy.
U.K. Law just limits the muzzle energy of unlicensed air rifles to 12 foot/pounds whereas some countries just limit the pellet velocity. (Usually giving different values for lead or alloy pellets) There can be conflicts between the two systems.
 
Thanks!! got the pyramid air sorted makes perfect sense now.

Airgun energy =14.6 ft lbs..... Pellet weight 7.56 = velocity 932.48 ft sec

Pellet weight 7.56 and velocity 932.48 = energy 19.80 Joules (just under )

find velocity for each pellet must remember that!
 
Just to add my bit. Uk limit is stated as less than 12 ftlbs for uncertified guns. So if your gun is 12 ft lbs it requires a fire arms certificate. It is my experience that the weight of the pellet can vary the power output of the gun. Generally a lighter pellet will give a higher output on a spring gun and a heavier pellet a higher output on a pcp. Softer pellets will deform into the rifling easier and give better output. In the UK, police can test your gun under certain circumstances and are free to use the pellet of their choice. If you don't have a fire arms certificate you need to be sure your gun is below 12 ft lbs with the best performing pellet.
 
divebuddy said:
Just to add my bit. Uk limit is stated as less than 12 ftlbs for uncertified guns. So if your gun is 12 ft lbs it requires a fire arms certificate. It is my experience that the weight of the pellet can vary the power output of the gun. Generally a lighter pellet will give a higher output on a spring gun and a heavier pellet a higher output on a pcp. Softer pellets will deform into the rifling easier and give better output. In the UK, police can test your gun under certain circumstances and are free to use the pellet of their choice. If you don't have a fire arms certificate you need to be sure your gun is below 12 ft lbs with the best performing pellet.
Click to expand...


Thanks for the info, thankfully i am in France so all is good
 
For complete peace of mind, invest in.....or find someone who has a Chronograph to check your rifle.
Springers are notorious for creeping up after being shot in.
Never trust what it says on the box......check it for yourself.

You will also need accurate information to get the best from Chairgun.
 
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Good tip many thanks, might invest in one they don't look that expensive, any suggestions?, My rifle was sold as 19.9 Joules so even a tiny bit might be dodgy
 
The link may help you Med.


Worth every penny when you think of the alternatives of not having accurate details of your rifle.
You will also get more accuracy from the various ballistic calculators.
 
Great link Bill. Here's my view. The cheapest is a Combro which fits on the end of the barrel using an elastic band or similar. You will hear varied reports from people who have shot them to pieces but they are accurate and cheap to repair. I have a Combro which is 10 years old and still working. I think they retail for about £45. I have replaced several parts at very low cost. For instance, a complete set of housing mouldings is only about £8. I also have a Skan chronograph which cost me over £100 second hand. With the Skan you fire the pellet through a "tunnel" about 75mm square. The difference in readings between the two is only a couple of feet per second so not a problem. If you would like I will post pictures. Also with the Combro I have a connecting lead to my laptop. This enables me to record a 10 shot string and graph it. This is handy to print off and keep in your gun bag in case you are stopped by police. You can demonstrate you are aware of the legal issues and have proof of "due diligence".
 
Just to add.....I would not go anywhere near a Chrono until you have put at least a tin of pellets through new the rifle.
Then do it.
Do it again after a few more tins have gone through the barrel to confirm it has settled down or if it needs attention.
 
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