GP100 4 to 4.2" change?

[Sal1950]

Can anyone tell me when Ruger changed from the 4 to the 4.2" barrels on the GP00s, either by date or serial number range?
Sorry if the answer was posted before but my searches were unproductive.
TIA,
Sal

 

[hittman]

In order to sell in Canada. Their government requires a certain barrel length which figures out to be 4.2".

 

[Sal1950]

In order to sell in Canada. Their government requires a certain barrel length which figures out to be 4.2".

Thanks hittman,
I know the why, what I'm looking for was when the change was made.
Best Regards,
Sal

 

[hittman]

Oops .... my mistake. Too big a hurry in reading your post.