In theory
The bullet in the 38 case has to jump .135" , That my friend is an asumption on our parts !!
The full dia. of the bullet would be shorter than .135" to "jump" from case to cyl throat & most I`ve measured are longer !
The bullet is coming out of the 38 case ,goes forward into the throat which in this case is .358" ( Most front bands on lead bullets are not 358) & is started well into the throat while PRESSURE is building BEHIND the bullet.
Now as the bullet base exits the 38 case & PRESSURE is higher now it blows by the base to fill the space .135" in length & approximately .012-.015" (depending on chamber demisions) exposing the body of the bullet to medium?? pressures for milliseconds of time ,but more importantly causing the base to wobble a bit , grant you it does`nt wobble much since as I said it`s "milliseconds" that this happens & it does happen as I`ve cleaned the evidence out of my chambers many times, known as the "38 dreaded crude ring" & would say in my opinion if I was gonna shoot 38 from a 357 chambered fire arm I would dedicate it to such & leave the crude rings be to help this problem ,I just would`nt shoot 357 length cases until it was "decruded"
This happens to all modern fire arms to some mynoot degree , hence the added importantce to a good even & square base on bullets !!!
This is my understanding & theory as explained to me by an old bullseye shooter.
Unfortunately most of us (me included
) can shoot em better because we don`t flinch , it`s a natural instinct , alot of us learn to either controll it or delay it to the degree it does`nt affect grouping ,but it`s there just the same.
For those of you that think ya don`t video ya self & slow it down a bit .
You`ll be suprised what ya see !!!