# Thread: u.s. and u.k. ft/lbs

1. ## u.s. and u.k. ft/lbs

i have been having a look at factory rounds to use in my new .243 and which would be good on fox as well as being legal for roe, ive had a look at fedral, winchester and hornady ammo and i'm working on and please correct me if im wrong to be legal i need a minimum of a .240 producing 1700 ft/lbs at the muzzel which i always thought was going to be about the 80gr mark but all above makes are claiming over 1800 ft/lbs even on there 55gr bullets and wondered if u.k. and u.s. ft/lbs are both the same un-like u.k. and u.s. gallons

2. same
in order to get the lighter bullets up to the limit they can clock them up to much higher MV

this is quite handy
http://www.airhog.com/convert.htm

3. Originally Posted by sir-lamp-alot
i have been having a look at factory rounds to use in my new .243 and which would be good on fox as well as being legal for roe, ive had a look at fedral, winchester and hornady ammo and i'm working on and please correct me if im wrong to be legal i need a minimum of a .240 producing 1700 ft/lbs at the muzzel which i always thought was going to be about the 80gr mark but all above makes are claiming over 1800 ft/lbs even on there 55gr bullets and wondered if u.k. and u.s. ft/lbs are both the same un-like u.k. and u.s. gallons
You seem to have misunderstood what ft/lbs are. The ft/lb energy figure is a function of velocity and bullet weight in relation to each other. To achieve a given energy level you can either get there using a light bullet at high velocity or a heavy bullet at a lower velocity.

4. i fully understand what ft/lbs are and altho i dont know the formula i understand how ft/lbs are calculated in relation to mass and velocity i was just under the impression that a .243 cartridge was unable to create the velocity needed to push a bullet under 80gr over 1700 ft/lbs hence ive questioned the u.k. and u.s. ft/lb scale but it seems to be after a bit of investigation that they are the same thing but many thanks for your help tho

5. US and UK only go out of sync on volume.

1 US Pint is 16oz by their volume measure but 20 oz by ours.

Weight is the same.

Stan

6. Originally Posted by smullery
US and UK only go out of sync on volume.

1 US Pint is 16oz by their volume measure but 20 oz by ours.

Weight is the same.

Stan
No. A US pint is 16 (US) fluid ounces while a UK (Imperial) pint is 20 (Imperial) fluid ounces, so is almost 25% heavier. It is not quite 25% heavier because the US fluid ounce is slightly larger (by about 4%) than the Imperial fluid ounce.

This is because the Imperial system is based on a gallon being the volume of 10 lbs of water, divided into 8 pints of 20 fluid ounces whereas the US system is based on an earlier definition of a gallon as the volume of 8 lbs of wine, divided into 8 pints of 16 fluid ounces. The Imperial fluid ounce is the volume occupied by 1 ounce of water while the US fluid ounce is the volume occupied by 1 ounce of wine; as wine is less dense than water, the US fluid ounce is slightly larger.

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