This might be a dumb  question but would it be better to get a glock in .40 S&W  and convert it to a .357 sig or get a .357 sig glock and convert it to .40 S&W.  The reason I ask is because I just wanted to know if one of the frames was made stronger then the other and would be a better match for both rounds. Sorry if this question has already been asked.

Quoted: ...would it be better to get a glock in .40 S&W  and convert it to a .357 sig or get a .357 sig glock and convert it to .40 S&W.

If buying new, Get the 40(a little cheaper unless a dealer has had the 357 for a long time), if buying used, get the 357SIG. Some find the recoil a little to harsh and just want get rid of it to get something else not knowing you can just swap barrels. Or that with a 9mm converision barrel you can shoot 9mm.  

If you do find a good deal on a FGR(Finger Groove - Rail) 40 get it. Glock standerize production so it will not matter if you shoot 357SIG out of it or not, the frames are the same.    

Thanks for the info!!

This might be a dumb question but why can't you convert a 40 to a 10mm? Is the case to long??

Quoted: .........why can't you convert a 40 to a 10mm? Is the case to long??

Yes, that is why the 10mm in in the larger frame Glocks