Why does the max filesize limit shows only half value if set and executed through the script?

Issue

• Why does the max filesize limit shows only half value if set and executed through the script?
• Setting ulimit -f <somevalue> in a script and running a process from the same, that process shows exactly the half value of the set value in ulimit -f output, why?
• See the example below.

[root@localhost ~]# cat test.sh 
ulimit -f 1000
echo " Let's see what's the ulimit value as of now, running commands, please wait!"
sleep 1
echo " The initial value of ulimit for filesize is `ulimit -f` "
sleep 1
echo " Setting up the new ulimit value now: For filesize its 512000 - The New One!"
ulimit -f 512000
sleep 1
echo " Successfully set the new ulimit value for filesize as `ulimit -f` "
sleep 1
echo " Running sleep now"
sleep 1000 & 

[root@localhost ~]# sh test.sh 

 Let's see what's the ulimit value as of now, running commands, please wait!
 The initial value of ulimit for filesize is 1000 
 Setting up the new ulimit value now: For filesize its 512000 - The New One!
 Successfully set the new ulimit value for filesize as 512000 
 Running sleep now

[root@localhost ~]# ps -ef | grep sleep
root      2393     1  0 17:00 pts/0    00:00:00 sleep 1000
root      2395  2127  0 17:00 pts/0    00:00:00 grep sleep

[root@localhost ~]# cat /proc/2393/limits | grep "Max file size"
Max file size             262144000            262144000            bytes  

• The script has set the ulimit -f to 512000 but the process is taking only of it's half (exactly half) i.e. 512000*1024=524288000 shall be the value, but its 524288000/2 = 262144000.
• Is this a bug? Is there any workaround?