Friday, July 15, 2005

Who needs foot-pounds?

By B.B. Pelletier

Foot-pounds of energy. Muzzle energy. What does it all mean? Well, it's a way to express the relative power of an airgun. When I was a kid, the big deal was shooting through one side of a tin can or sticking a pellet in a piece of wood. Both were considered the measure of power for an airgun.


Benjamin's 3030 BB gun was made for about a decade, starting in 1965.


Benjamin recognized this and advertised their new 3030 CO2 BB gun as being able to shoot through BOTH SIDES of a 5-gallon steel pail! They knew who their customers were and what they wanted! Of course in my day, cans were actually made of steel plate, and common airguns were nowhere near as powerful as they are today.


The 3030 ad speaks for itself


Super penetration from Sheridan
In the 1950s, Sheridan ran an ad showing the penetration of ONE INCH of wood! You think that didn't freak us out? Those demonstrations meant more to us as kids than foot-pounds would have. We didn't learn about foot-pounds of energy until eighth-grade science class, and, judging from the confusion among airgunners today, I'd say they haven't taught it in years.

Velocity is a selling point
Velocity became the big selling point until airgun velocity went so high that it no longer has any real meaning. I remember cars in the 1950s that had speedometers that read up to 120 mph, even though the cars they were in would top out at 95. Besides, where do you drive 120? I don't mean where CAN you do it - just where DO you do it? It's better to have a car that always starts and always gets you where you're going than to have bragging rights based on a speed that may not even be safe in that car. Real fast airguns aren't accurate at those speeds, SO WHO CARES?!

Foot-pounds make more sense
Foot-pounds bring things back into perspective. A Beeman Sportsman S500 generates about 5 foot-pounds at the muzzle. A Beeman R9 generates in excess of 14 foot-pounds at the muzzle. Which one is the better airgun for hunting? It's a no-brainer! A pellet from the R9 will still be at 6 foot-pounds (one more than the S500 at the muzzle!) at 45 yards! A REAL no-brainer!

Comparing guns by foot-pounds makes everything clear. If it takes 6 foot-pounds to humanely kill a squirrel, then no one needs to ask which air pistol is suitable for hunting squirrels. They all generate LESS than 6 foot-pounds at the muzzle.

This website has a handy energy calculator for you to make your own foot-pound determinations. Don't know what weight pellet they used for a gun's velocity test? Guess! It's a cinch the Beeman P1 doesn't get 600 f.p.s. with 25-grain .177 pellets. You can't even FIND 25-grain .177 pellets!

Try to get on board with energy figures, if you can. They can take you to the next level of airgun enjoyment.

19 Comments:

At July 15, 2005 11:36 AM, Anonymous Anonymous said...

I know this has nothing to do with the post, but is there any way you could post about shooting techniques?

 
At July 15, 2005 12:08 PM, Anonymous B.B. Pelletier said...

Sure, I'd be glad to. Can you tell me more about what you are looking for?

For example:

Pistol shooting
Offhand rifle
Benchrest rifle
Field target

or something else?

B.B.

 
At July 15, 2005 2:29 PM, Anonymous Anonymous said...

Just air rifle shooting in general like breathing techniques and follow throughs. I would also like to know if there is any specific method to double tap a semi-automatic co2 rifle.

Thanks

 
At July 15, 2005 2:52 PM, Anonymous B.B. Pelletier said...

I will try to address your questions in Monday's posting.

Thanks,

B.B.

 
At July 25, 2005 5:47 AM, Blogger nordattack said...

I don't believe that velocity or foot pounds are an effective way to calculate the power of an airgun. The reason is simple, each rating is dependent not on the force of air a particular airgun can create, but instead on the weight of the pellet used. Airgun manufactures mostly rate their guns in velocity but do not give the weight of the pellet used. As an example, the RWS 350 lists it's .177 cal velocity as 1150fps and it's .22 cal velocity as 1050fps.
This tells us nothing because we don't know what weight pellet was used. For all we know a 3 grain pellet was used and with a more standard weight of 8-10grains the velocity might only be 500fps.
If we are simply told an airgun has 25 foot pounds at the muzzle again without knowing the weight of the pellet we are clueless. I mean it could be a 900 caliber pellet going 5 feet per second!
I suggest that a new type of standard of measurement be created that involves no pellets. Rather let us test the force of air ejected from the air chamber. This force will be the most reliable way to know what an airgun can do. With this measurement we can them plug in pellet weight and get velocity and foot pounds.
A made up example would look like this: The RWS 350 generates 1000 psi at the breech. 1000 psi at the breech can propel a 10 grain pellet 1000 fps. Note this is just a made up example. But once we have a psi to pellet weight ratio then we can use this formula to calculate any velocity for any pellet weight as well as foot pounds.
An earlier blog stated that to use the Eun Jin 16 grain .177 cal pellets with accuracy it was necessary to have an airgun that could produce 25 foot pounds at the muzzle. That's great but how can we know what velocity a given airgun can propel a 16 grain pellet at? There is no way to know. I have an RWS 52, can it propel a 16 grain pellet fast enough to produce 25 foots pounds? Who knows?
If some technician would just test each airgun's force at the breech then measure the velocity of a given pellet weight like 10 grains then we could go from there and know everything about the guns potential.
Comments welcome.

 
At July 25, 2005 6:09 PM, Anonymous B.B. Pelletier said...

Wow! I'll have to chew on that awhile before I address it.

Thanks for your thoughts,

B.B.

 
At July 25, 2005 9:12 PM, Anonymous Anonymous said...

I agree with nordattack, although I believe that at some point I read that manufs are supposed to publish velocity for .177 cal with 7.9 gr pellets... Anyway, it does not solve the problem of course, generally speaking (for other calibers). I am not a novice and I could never understand how they can even talk about velocity being the only value they advertise. Instead they should always advertise the power of the air gun (e.g. 4 Joules or 2.95 ft/lbs will mean something, e.g. 410 ft/sec with 7.9 grain pellet and 364 ft/sec with 10 grain pellet). I think manufs are publishing the velocities so that regular Joe (no offense, Joe M.D. :-) can actually relate to something...

 
At July 25, 2005 9:28 PM, Anonymous Anonymous said...

I know this doesn't pertain to the current topic, but is the new GAMO air pistol made of plastic or what? I would like something that won't break when I drop it, but I don't have alot of money. Can you help me. P.S I really would like a GAMO Pistol.

 
At July 26, 2005 4:23 AM, Anonymous B.B. Pelletier said...

Can you give me a model number for the Gamo pistol?

B.B.

 
At July 26, 2005 4:35 AM, Anonymous B.B. Pelletier said...

Agree with Nordattack,

I think you really disagree with him. He says he DOESN'T like foot-pounds as a measure of power. He wants psi ratings for all guns, and he's giving spring guns as his examples..

I'm still trying to find a way to answer him, but his comment seems to cotradict itself in places. I understand that he wants something other than velocity or foot-pounds, but I think the breech pressure he proposes is likely to be just as arbitrary.

What assurance do we have that all guns will shoot pellets of the same weight at the same velocity when powered by the same air pressure in spring guns, when that doesn't happen right now in PCPs?

I am still thinking about what he says and trying to make sense of it, so I can comment.

B.B.

 
At December 21, 2005 1:55 PM, Anonymous Anonymous said...

I agree that the advertised velocity of an air gun doesn't tell us much but I completely disagree with what Nordattack said about the muzzle energy. Muzzle energy tells us EVERYTHING. All you have to do is just plug in known pellets weights in an energy calculator and plug in some velocities until you come out with the advertized energy. Even though different pellets will slightly vary in their energy, this method will still give you a very good idea of what your gun is capable of....assuming of course that the company is not lying about the advertised muzzle energy to begin with. For example if your .22 cal air gun is advertized to produce let's say 30 ft-lb. of energy...right from the start you know that you can start with some heavier pellets...I would start with good quality, accurate pellets that I like...I would plug in the 21 grain Kodiak in the energy calculator and plug in some velocity numbers like 700, 800, 900 etc. and you'll find that 800 fps is almost 30 ft-lb. energy with a 21 grain pellet. Let's say you want to shoot the 16 gr. JSB exact, well if you do the same thing in the energy calculator you'll see that 30ft-lbs. means that pellets will be going around 919 fps.

 
At December 21, 2005 2:41 PM, Anonymous B.B. Pelletier said...

Thanks for a well thought-out comment that was also expressed clearly. I think you've written half a blog for me!

B.B.

 
At December 31, 2005 12:48 AM, Anonymous Anonymous said...

To calculate rifle foot pound energy the formula is bullet weight in grains times the volocity squared divided by 450,400.

Hope its helpful - Steve from West Point

 
At December 31, 2005 10:29 AM, Anonymous B.B. Pelletier said...

Steve,

Thanks. Did you see the two-way energy/velocity calculator on this site? Is in the articles section under muzzle energy.

B.B.

 
At January 22, 2006 2:52 PM, Anonymous Anonymous said...

Great article!

I disagree with nordattack because I don't think the Kinetic Energy (ft/lbs) would change much with any pellet in the range of weights they are made in. Obviously you can't shoot a "900 caliber" round from your airgun, so that's irrelevant. You have to stay within a practical range of weights. When you shoot a lighter pellet, energy doesn't change much, because your velocity increases. When you shoot a heavier pellet, velocity decreases, but the weight of the pellet makes up for the loss in speed. Just my opinion. I am not an expert in the field! Again, thanks for the article.

 
At April 12, 2006 3:37 PM, Anonymous Anonymous said...

You need 2 peices of information at a minimum.
1100ft/sec is an advetizing trick.
Sounds good but leads the barrel and is loud.
900ft/sec, 14.3g, 30ft/lb and 22cal gives you power, bullet drop, effective range and some idea of what it can be used for.
Pellet weight is not much help by itself. I have a range of 7.9 to 30g on my shelf and without adittional information can mislead you.
low speed and a fixed distance is good for target while high speed helps with variable range. Maybe this is why most people end up with more than 1 gun in more than 1 caliber.

 
At May 21, 2006 1:13 AM, Blogger Mountain_Mike said...

nordattack said, QUOTE: [I suggest that a new type of standard of measurement be created that involves no pellets. Rather let us test the force of air ejected from the air chamber. This force will be the most reliable way to know what an airgun can do. With this measurement we can them plug in pellet weight and get velocity and foot pounds.
A made up example would look like this: The RWS 350 generates 1000 psi at the breech. 1000 psi at the breech can propel a 10 grain pellet 1000 fps. Note this is just a made up example. But once we have a psi to pellet weight ratio then we can use this formula to calculate any velocity for any pellet weight as well as foot pounds.
An earlier blog stated that to use the Eun Jin 16 grain .177 cal pellets with accuracy it was necessary to have an airgun that could produce 25 foot pounds at the muzzle. That's great but how can we know what velocity a given airgun can propel a 16 grain pellet at? There is no way to know. I have an RWS 52, can it propel a 16 grain pellet fast enough to produce 25 foots pounds? Who knows?
If some technician would just test each airgun's force at the breech then measure the velocity of a given pellet weight like 10 grains then we could go from there and know everything about the guns potential.]

I see at least one major problem with this proposal! Knowing the pressure of the gas or air that pushes a pellet doesn't tell us very much... The BARREL LENGTH makes a significant difference if the pressure and pellet weight are known. This is a step backward from muzzle energy (foot-pounds).

Muzzle energy has also been duplicated in his example: "1000 psi at the breech can propel a 10 grain pellet 1000 fps" - this is an example of muzzle energy, so why would anyone need to know the pressure at this point? It's a silly duplicate - or actually step backward - in an approach to understanding what any pellet gun or firearm can do.

 
At September 30, 2006 1:02 PM, Anonymous Anonymous said...

I Have A Gamo Hunter 1250. I'm looking for the most power Pellets i can use with that gun I'm using it for hunting.. its the .177

 
At September 30, 2006 1:10 PM, Anonymous B.B. Pelletier said...

Because your rifle is a springer, it develops the greatest power with light pellets. However, it also shoots light pellets too fast for accuracy. You want to stay below 900 f.p.s. for the best accuracy.

I would try Beeman Kodiaks, JSB Exact 10.2-grain pellets , Crosman Premier 10.5-grain, and 16.1 grain Eun Jin pellets.

B.B.

 

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