243 is a very good versatile little cartridge. But it relies on velocity to give lots of hydrostatic shock, rather than a big bullet going slowly making a bigger hole.
In Scotland there was a min of 100gn requirement for the bigger deer. The 100gn bullet was always on the edge of stability in the typical 1 in 10” twist of the 243. It’s why most 243 100gn loads use a flat based bullet rather than a sleek boat tail high BC type bullet.
Certainly in my 243 Heym SR20 I found it to be pretty sensitive to cartridge. It shot RWS 100gn T Mantle very well. Then they changed their loading and seated the bullet deeper - and this substantially opened up groups. I also had problems with lack of penetration on Reds with bullet expanding too fast and not penetrating shoulders.
Now that we have an 80gn min in Scotland, we can use all sorts 80 to 95 gn bullets. These are absolutely within the spin rate stability with higher velocities more than making up for loss in bullet weight. Most of these lighter bullets are of more aerodynamic shape and thus probably have a better BC.
With a monolithic bullet you get the toughness and weight retention so that the bullet will penetrate into the vitals if even the biggest deer. From what I have read the 243 with an 80 to 85gn monolthic is more than adequate for elk or kudu.
A 243 does however need a decent length of barrel to enable a full powder burn to hit the 3,000 fps plus velocity’s. It’s an overbore little cartridge - it’s a baby magnum type of rifle. 22, 24 or 26” are ideal.
The current fad is for short 16 or 18” barrels. 243 struggles to make adequate velocities in such barrels, unless you do something funky with powders.
243 kills by velocity with hydrostatic causing a large temporary wound channel. This does cause quite a bit of bruising. With a monolithic bullet that remains in one piece this is unsightly rather spoiling large amounts of meat with lead fragments.
The 243 is fast and flat shooting, and with a typical 4cm high at 100m sighting you don’t need to worry about range till well over 200m.
However the current fashion is for a short barreled rifle shooting a long for calibre high BC bullet at 2650, 2700 ish launch velocity and using technology to range find and adjust sights for perfect impact at further distances.
I am old school - anything over 200 is really too far. I want minimal fuss and use point blank range approach.
