PJames wrote:Typo Yes, .476 sorry about that. The berry bullets grouped ok at 30 yards had several touching but, I was not shooting for groups maybe next time. They seemed ok for plinking no sign of bullets going sideways nice round holes.
Well, the proof is in the pudding. We banter a lot about 100 yd groups even though the lethality of this caliber is such that you don't need 1 MOA performance unless you're pushing them out to 250 yds and beyond. Geometry doesn't lie. Doesn't have an agenda. Doesn't represent a monetary interest. It clean and antiseptic. It also says that POI over POA errors increase the further the path of travel gets. A 3 inch group at 100 yds is something like a 10 inch group at 300 yds and that's not even factoring in wind that can be blowing at different velocities and possibly directions along the way.
So resultant groups, while mostly relevant to the shooter's hunting needs, are at least a predictor to how a load may perform at a range over what the original shooter's needs were. The accuracy which produces a 10 inch group at 300 yds, produces one ragged hole of less than an inch diameter at 30 yds. Not suggesting you were content with that performance distance. As you implied, it was to test reliability and repeatability.
So, aside from verifying reliable cycling and ignition, we all don't have a lot of choices for quality metrics other than groups, hence the interest in them.
In this fat caliber, the price we pay for making weight with solid, lead cored bullets is them being shorter, sometimes significantly so, than their hollow point or all copper equivalents. That may leave more capacity for powder, but in a mouth headspaced caliber, it poses a challenge to getting a crimp that holds the bullet in one spot during the inertial effects of chambering and the lesser effect of recoil down in the magazine. Thicker walled cup and core bullets will resist deformation more than thin walled, plated bullets. The result of that is a tighter pinch when the case mouth is compressed down upon them. Think trying to hold into a water balloon vs a grapefruit of the same size. The resistance to deformation is important as is the memory of the medium. Squeeze an egg of Silly Putty and then just the Silly Putty itself. One springs back, one doesn't. The shell matters.
Its warmed up to +24 in the sun, so time to do my Sunday preventive maintenance down at the club rifle range.
Happy New Year everyone.
Hoot