M1897 vs M2 75mm cannon vs M3 75mm cannon

I have read that the M2 cannon as used on the M3 Grant/Lee was the same calibre length as the M1897?
The M3 is slightly longer?
How much difference in the actual gun is there?
I have looked around and I cant really find great pictures of either breech blocks and "innards" of either.

 

The M1897 gun's length was in-between these two. It was 36 calibers long, I believe. Muzzle velocity for AP shell was between that of other two as well.

Edit: here is a quote from TM 9-1901 "Artillery Ammunition" from 1944:

 

thanks!

 

Some extra information on this topic for future visitors:



Source: https://apps.dtic.mil/sti/tr/pdf/ADA800118.pdf

 

In functional terms, the M1897 had an unusual rotating breech whereas the M2 and M3 had more conventional sliding breechblocks.

 

thanks you!

 

Thanks!
I have seen the breech of an M1897, but not the M2 or M3 in person.