After several years of just loading any old boolits for my 30 cals I've come to the stage where I want to refine my system and just end up using one boolit.
Here's an image of a handful that won't make the cut though it's a close thing between the one in the centre and the one I've chosen.
https://castboolits.gunloads.com/images/attach/jpg.gif
I'm loading for 30/30 and 308 and have finally decided to use the Lee 309/170 gc fn in both rifles, basically it comes out at 173 grns with a hornady gc on and smothered in mule snot and shoots regularly into 3 - 4" at 100 yards with the 30/30 and amazingly into 1 - 1.5 groups with my 308 BLR.
The boolitts shown in the image are nearly as good in the 308 but the 167 grn pb with a pb gc on shoots 2 -3" in the 30/30, the others not so well and the 120 is crap.
All those boolits in the image are store bought but the lee will be cast by myself.
The query that I have concerns the 308 with the COAL at 2.8", the cast section in front of the crimp groove is engaging the rifling by about 0.020", the only drawback is this makes the lever stiff over the last few degrees of action as the bolt goes into battery. This doesn't appear to be a huge issue but the load I'm using with about 18.5 grns of 2400 is quite mild, gives about 1850 fps at the muzzle. The same bullet in the 30/30 does not get engraved with the rifling at COAL of 2.55 and I've been loading it with RL7 at around 2100 when it's been knocking out those best for me out of the 30/30 groups. The reason I've been loading the rounds at max for caliber COAL is to minimise the pressure.
Is this issue of the boolit engaging the rifling bad, good or indifferent? I ask as I have several hundred of these boolits remaining and want to use them up. BTW the 308 does the same thing with the 180 and just nudges the rifling with the 177.