19 February 2019
I don't have that particular mold but it appears to be Lyman's interpretation of the RCBS 308-165-SILHOUETTE bullet. The RCBS has a ~.375 long body and an intended nose bearing length around .312. if the nose is under bore diameter, you don't really have enough bearing length for good guidance down the barrel. This is maybe a little worse due to the fast powder used. The Lee 309-150-F has a body just under .50 long and a nose bearing length around .200. A third more body bearing length and a third less nose that COULD be unsupported maintain alignment much better. The nose on my Lee 150 runs .299/.301 (which does well in a lot of barrels).
You could lap the undersized nose on the Lyman out to provide a better fit if you have some basic tools. I do my lapping by hand rather than power since it is much easier to keep things from going wrong as fast. That may reduce the allowable alloy choice to maintain a usable fit. I have found that the nose on my RCBS 308-165-SILH will expand about .002 if I cast them from ~11 BHN wheelweights and seat and crimp a Gatorcheck on in a .309 die in the lubrisizer, which is convenient. I do NOT recommend trying to deliberately bump the diameter of any hard allow in a librisizer since that tends to overload and bend/break the operating linkage.
The 311440 can be very accurate and extremely effective as a hunting bullet but it's got the ballistic coefficient of a beer can and slows down fast. It might not be real happy by the time it reaches 200 yards but sometimes things work out regardless of initial impressions. I ran them out of a 94 Winny at 230 yards but it was on some fairly big steel targets so it was difficult to determine grouping ability.