discrepancies in file size of similar parts

Hello

For a multitude of reasons, I decided to make my own mini toolbox of Hex Bolts with dimensions taken from Mcmaster. 

The parts consists of an extrude (hex head), a cut-revolve (top chamfer), extrude (thread length), and chamfer (thread end).  I started with 1/4"-20 bolts, and created configurations from 1/2"L to 3 1/4"L at 1/4" increments.  Then I "saved as" and did the same thing for 5/16" and so on.  The only things I modfied was the hex head dimensions and the thread diameter. 

For some reason, my file sizes are ranging from 250kb to 1mb. 

For example my 9/16" hex bolt is 1 mb+

                         3/4" hex bolt is 255 kb

                         5/8" hex bolt is 521 kb

They're all created from "saving as" from 1 size previous.  All the files have the same 4 features (2 extudes, 1 rev cut, 1 chamfer)

One of the reasons for this is to reduce file size and to simplify my assembly.  Any suggestions?   Thanks

EDIT - when I reopened and saved the 3/4" just to check the file before uploading the part, it went up from 255 kb to 623 kb.  I have a similar 7/8" bolt that has a low file size. 

SolidworksGeneral