weird shadow on my model

[weird shadow on my model]

I don't understand why the glock pistol don't have such shitty shadow without any setting,and my model which I made last year don't have such shitty shadow too.Is there any setting not correct in the blender?such as face normal or something

[weird shadow on my model]

Hi,guys

I'm modelling a pistol for VMEPLA MOD,but when I exported the lowpoly model into the O2,I find some weird shadow along the edge on my model. I don't know how to describe it ,so this is the picture

I wondered there is some thing wrong with my model,so I creat a cylinder and smooth it,the model still have the same problem

Then I imported a GOLCK(download on websit) into O2,it don't have this weird shadow

ALL these model are modelled by Blender,and exported by the FHQ Arma toolbox for Blender,I even use the BLender 2.64 version to export the model(in OBJ,this version don't support the toolbox),but still have the same problem.BTW,I use Blender 2.70,the version of FHQ Arma toolbox is 1.5,I still use BI editing tools 2.5 because the new tool dosen't work well on my PC.

Thanks for your time.

[[Tutorial] Simple Re-texturing Guide (From Start To Finish)]

thanks,it's very helpful to me!!