I'm curious as to twist and stabilization. Does a slow twist throw wide patterns but make perfectly round holes or will the unstable bullets key hole?
I've seen that happen two times and it was obvious.
If I'm not mistaken a 1 in 10 will stabilize a 69 SMK and I've had a 1 in 9 stabilize 77's.
And if a slow twist causes poor groups with heavier bullets, why doesn't a fast twist do the same with light bullets?
Serious questions.
I suspect this can be called voodoo. I've had some fast twist ones shoot lighter bullets not so well. I've had them puff a few too, but thats different.
To slow of a twist has always keyholed the bullets for me, but its so minute its hard to see if you are not really looking for it.
We had a 10 twist that would not shoot 69s once years ago. It was actually a 10 also as checked, but I've had 10s since that did just fine.
A buddy of mine shoots 9 twist on purpose, 20 inch tubes, and he runs 80s at 600 and beyond. He has never had an issue but he has also said he knows he is on the ragged edge most likely.
I would think that in this issue the 69s would be keyholing just a bit since they are not grouping well.
In this instance I just don't see how it can be anything but the barrel issue. You can't have ammo shooting snug groups, IE 1-1.5 inches appx at 100, and then come along and a PROVEN load and PROVEN bullet be heading towards 4 inch stuff.. That just should not happen.
BUT as we all know, sometimes things just happen. Maybe its not the twist, but having seen that a few times, thats what makes me stand firm on betting this is the same thing.
And I could easily be wrong.
I was fortunate that when we were shooting, we shot a LOT, knew a lot of folks, helped a lot of folks, loaded and shot lots of ammo and when you shoot almost every weekend in different locations across TX and the US even, you have a lot of exposure. Where it not for that some things I'd have never seen with my own two eyes.
Now if the barrel shot FGGM and the others all to around 3 inches give or take, I wouldn't nearly be as sure that it was likely a twist issue, but rather an issue with QC somewhere in the gun/barrel....or even could assume the shooter was not up to snuff.