FT/LB

[Guest Callum.]

How many ft/lb do you think 570-580 ft per second is?

[George1990]

Depends on the weight and the ballistic coefficient of the bullet/pellet

[milo2005]

need the pellet weight

[Guest Callum.]

I don't know...

it just said Ft/second 570-580 and other guns say foot / lb

[SSS]

Where have you found that? is it .22 or .177?

[Guest Callum.]

It's a .177

[Paddy Galore!]

where and on what did it say this? Be specific!!!! what you've stated is the muzzle velocity.

[Guest Callum.]

Well it was on a website called Antics Online and i don't know anything else it doesn't say!

Its only a cheap gun and i don't want to buy a weak thing that won't kill quarry and leave it with a wound!

[SSS]

580 fps seems slow for a .177, I thought they were nearer 700 if they were legal limit. I've never been a fan of .177

[Guest Callum.]

Hmm Ok.

This is why I don't like air rifles much

cost so much for a decent one and then there is all this technical stuff

[Paddy Galore!]

well, a legal 177 air rifle will chuck an average pellet out at about 900ish ft per second, thats about 11ft/lb. 570 ft/sec is slower than a 22.

hope this helps.

[Guest Callum.]

Ahh ok.

Thanks i'll keep looking then I guess

[bennyblanco]

Just under 800fps is legal limit for a .177 8.4gr pellet like air arms field/jsb etc.

just under 600fps is legal for a 16gr .22 IIRC

 

Sub 600fps .177 is near pistol energy and only suitable for close range rats, there are plenty of springers you can buy for sub £100 second hand that will be powerful enough to kill-its better than buying a brand new piece of poo.

[Guest Callum.]

Ok cheers

[mickmep]

my rapid is doing 712 fps using bisley magnums at 10.6 grain

which gives a ft/lbs of 11.94. using a combro mk4.

the ft/lbs goes down if using lighter pellets like jsb's but i dont have a fps reading for those.

[HW682]

Also note that it is ftlb or ft-lb or even ft.lb but not ft / lb which would be feet per pound and that is not a unit of energy.

 

HW682

[Guest Callum.]

Sorry einstein i'll make sure I correct it in future

[Guest Callum.]

Thankyou Mick

[HW682]

I think you mean Einstein? (with a capital E)

[farmboy99]

i think 900fps is more like 15 ft/lb usually unless its a really light pellet.

But yeah it sounds like a weak gun for a .177 ive got a basically new weihrauch 77k putting out close to legal limit if youre interested give us a shout. ive just brought a hw97kt so the 77k is redundent although it is basically brand new itself. cheers tom

Edited February 14, 2010 by farmboy99

[covlocks]

Go on to the Air Arms site and there a some good spreadsheets for calculating muzzle velocities, power v pellet weights etc. If I can find them on my ,puter, i'll post.

[covlocks]

I have found a quick way of doing the calc using a spread sheet.

 

=((pellet weight in grains/(7000*32.174))*muzzle velocity^2)/2

 

answer is in Ft/Lbs.

 

Put that into a spreadsheet and you have a good guide. I would have posted the small excel file, but it refuses to work for me. Email or PM me and I will send it if needed.

[Guest Callum.]

Thanks Covlocks!

[robbobsam]

To calculate the Ft/lb of an air rifle you do the following calculation.

 

ft/lb = Velocity of pellet (feet per second) x Velocity of pellet (feet per second) x Weight Of Pellet (Grains) / 450240

 

eg, 712ft per second x 712ft per second x 10.6 grain pellet weight, divided by 450240 = 11.93ft/lb

 

Simple !!!

[Dekers]

well, a legal 177 air rifle will chuck an average pellet out at about 900ish ft per second, thats about 11ft/lb. 570 ft/sec is slower than a 22.

hope this helps.

 

 

I think the maths has gone a little wrong there, an Average .177 at 900 ft sec will be well over 12ft lb, not, about 11ft lb, to be honest you would have to find a VERY light one to be legal at that speed!