Retesting the 160 grain plain base 357 mag revolver load: last time I noticed that the bottom lube groove was getting obliterated in the revolver, so I wanted to see if that also held true when the same load was shot from a rifle?
Once again the bottom groove was 90% obliterated from the revolver and the 2nd to bottom groove was about 50% obliterated. The grooves survived mostly intact when fired from the Marlin. Obviously "something" is happening in the revolver that traumatizes the bottom grooves. Whatever that "something" is, it doesn't happen in a rifle.
The revolver bullet skidded a little on the front band. That seems normal for revolver bullets so I'm not going to worry about it.
You can't tell from this photo but the revolver bullet is more smushed on one side than on the other side. That was true of last week's revolver bullet, too. That concerns me. I suspect the revolver bullet is either yawing badly inside the barrel, or else it is entering the forcing cone off center. I suspect the latter because it's a common problem with revolvers. It's amazing that this load shoots as well as it does with the mangled, off center bullet.
Note the base of the revolver bullet is mostly flat while the base of the Marlin bullet is beat up and uneven.
Another view of the bases. Sorry for the fuzzy photo, but the revolver bullet was mostly flat and grainy while the Marlin bullet was mostly shiny but cratered and generally beat up. This load has never been accurate in the Marlin and you wouldn't expect it to be accurate if the base looks like that when it exits the barrel.
I assume the grainy look on the revolver bullet base is due to it being blasted with unburned granules of powder?
At this time I have no explanation for how the Marlin base got so beat up, other than to say that it was exposed to hot gases for a longer period of time so maybe it got warm and soft ????? Just a guess. Lessons Learned:
-- "something" is wiping out the bottom grooves of the bullet in the revolver. If it were due to obturation then I would expect bottom grooves to get wiped out in the Marlin, too, since it's the same load at the same pressure. What if the revolver bullet is experiencing the "Paradox Effect?"
-- alternative explanation for the wiped-out grooves: what if the bottom half of the bullet is obturating A LOT in the forcing cone? And then when it enters the rifling the bands get sized back down to normal size but not so much the grooves??? I say that because someone once tried shooting a revolver with its barrel removed and the resulting bullets had grossly obturated bases, suggesting there is some serious obturation going on when the bullet exits the cylinder.
-- "something" is mangling the base of the bullet in the Marlin. Maybe due to getting too hot and soft, but I'm not at all sure???Things to Try Next Time and Down the Road:
-- test the revolver load in the Contender barrel, too.
-- if the wiped-out grooves are due to the "Paradox Effect" then maybe I should try imitating a Paradox bullet with its oversize groove(s)?
-- if the wiped-out grooves are due to massive obturation in the forcing cone, then maybe a harder bullet would help? These bullets are oven treated WW but the box is dated 2004 so they may have softened to around 20 BHN.
-- I'm up to my ears in projects right now so it may be a loooooong time until I can follow up on this revolver bullet mystery.