To what COL were you seating those FMJ's?
IMHO, of all the bullets greater >= 200gr, they are the hardest to get a good purchase on. That's why you need to set them to a COL of only around 2.05-2.10 inches. That having been said, seating them without a crimp of some kind will make them too loose to cha-cha. I saw what you did once myself, when trying to load some C.O.P. 160gr bullets. Not because I didn't use a crimp, but because I later discovered that they were only .446-.448 in diameter. The net result was equivalent to no crimp. Nothing worse than a squib load that gets stuck a little down the barrel and when you jack it open, all that unburned powder falls down into your trigger group.
TexasSheepDawg has had good luck with the 230's because he applies a stab crimp on the side using a modified Lee 45-70 Factory Crimp Die. Being a smooth-sided bullet doesn't help either. Nothing to crimp down into, like the FTX's.
Try applying enough taper crimp to yield a diameter of .476 measured using a micrometer as close to the actual mouth edge as possible. Don't worry about the rim spilling past the edge of the chamber. I intentionally crimped a test dummy cartridge, using a soft Berry's 230 FMJ once to see where that actually occurs. IIRC, it was down around .460 measured at the mouth. That's not meant to condone crimping the 230's down past .476 however. You'll just make the case mouth walls permanently squeeze thinner and distort the bullet to where it looks like a domed air rifle pellet. If you want affordable plinking bullets, watch for a bulk blem sale of Hornady 225gr FTX's from Midway and load up on then when you do. The cost per bullet will not be much more than bulk 230 FMJ and you not only get a true .452 bullet, you get a cannelure to crimp down into. My best 5-shot group ever was using 225 FTX.
Even when they're not on sale, you can find them for around $26.13/100 such as at
ManVentureOutdoor. Those are good folks to deal with. At 3.3 pounds, they're not cheap to ship, but do some comparison online shopping or check local merchants.
Hoot