When I downloaded 1.7.2 forge and open it with minecraft.It launched unsuccessfully and appeared the words :

[19:56:55] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker

[19:56:55] [main/INFO] [LaunchWrapper]: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker

[19:56:55] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker

[19:56:55] [main/INFO] [FML]: Forge Mod Loader version 7.2.211.1121 for Minecraft 1.7.2 loading

[19:56:55] [main/INFO] [FML]: Java is Java HotSpot 64-Bit Server VM, version 1.8.0_25, running on Windows 7:amd64:6.1, installed at C:\Program Files (x86)\Minecraft\runtime\jre-x64\1.8.0_25

[19:56:55] [main/WARN] [FML]: The coremod codechicken.core.launch.CodeChickenCorePlugin does not have a MCVersion annotation, it may cause issues with this version of Minecraft

[19:56:55] [main/WARN] [FML]: The coremod codechicken.nei.asm.NEICorePlugin does not have a MCVersion annotation, it may cause issues with this version of Minecraft

[19:56:55] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

[19:56:55] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker

[19:56:55] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

[19:56:55] [main/ERROR] [LaunchWrapper]: Unable to launch

java.util.ConcurrentModificationException

at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901) ~[?:1.8.0_25]

at java.util.ArrayList$Itr.remove(ArrayList.java:865) ~[?:1.8.0_25]

at net.minecraft.launchwrapper.Launch.launch(Launch.java:117) [launchwrapper-1.9.jar:?]

at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.9.jar:?]

Java HotSpot 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release

Don't use 1.7.2, Update to the latest 1.7.10 forge.