For starters, understand the bullets you have, and what they are intended for.
.358 Hornady Frontier Lead SWC is indented for light target load, and not full power loads. In regards the powder being used, it should have a burn rate in the Bullseye range, and anything in the unverial burn range or slower, is the wrong powder to be using with these soft bullets.
The soft (read pure lead with light waxing) is very uniform in weight and size for an ideal target load. If you crank on the speed to bring them up to full power loads, your going to be scrubbing lead of your barrel for days, and ending with nothing but problems and bad groups sizes as well.
Second, make sure that your bullet seating steam matches the bullet nose shape that you are using.
Since they are flat nosed bullets, you should be using the seating stem shape on the left hand side,
Thirdly, you have to flair the case mouths enough that when seating the bullet squarely against the case to start with, the lip of the case mouth is not shaving the brass.
With the soft lead bullets, will need to flair the case mouths about this much with a standard flaring tool to prevent shaving,
Lastly, you dealing with a soft lead bullet designed for slower target speeds, so take it easy when bullet crimping!!!! The bullet you are using is for 38 type light target loads, which means that you have a roll crimper in play, and its way to easy to over crimp the roll crimps on the soft lead to really carve a channel into the side of the bullet via the case mouth to cause even worse leading problems.
Your bullet crimps should look like this.
With this much bullet crimp way to much instead.
Also to point out, if you start loading wad cutter with hollow bases (think minnie bullet design), slow the speeds down even farther. Hence the bases are hollow to expand at the reduced pressures to engage the rifling correctly, and if you try to push these hollow base bullet designs faster than intended, your working pressure will sky rocket instead (gets worse as the barrel leads up faster as well).