Short answer don't, a 243 is NOT a brush calibre. The bullet will be deflected off course by any gads , twigs, and brush it encounters on its journey from the barrels end to the deer. Any projectile can be deflected. But a 95 to 100 gr. 243 at 3000fps doesn't take much of a twig to deflect it off course. Best result is you miss the deer, worst case you end up wounding the deer and loosing it. I shot at a deer several years back at 25yds with my .243 loaded with 95 gr Nosler partitions. There was some tiny maple gads/brush between me and the deer, not that many either. The bullet never reached the deer. He ran off about 60 yds., stopped, turned and looked back in my direction and then left. Shot a deer from the same stand with the .243 the next day, but this time I waited until the deer was on clean ground and not a thing between the end of the barrel and the deer but air. Dead deer without issue. The .243 is a fine cartridge and is very capable of killing deer provided you have clear air between the gun and target. In my experience it is definitely not for shooting at deer in brush of any sort under the conditions you described in your post.