Of the many forces that affect accuracy, barrel vibration is probably foremost. Read more
Then push the bullet all the way through with a close fitting hardwood dowel or a plastic-coated cleaning rod.
It must also have a high B.C to enable it to shoot flat, lie close to the wind and deliver maximum energy to the target at long range.
I don't think there's any danger just as long as you don't try to equal the ballistics of the .308 Win.
The Arrow is no more than the Swift case fireformed to increase the shoulder angle to 30 degrees.
Your idea of using Hornady cases carrying the .275 Rigby headstamp is nostalgic.
My advice is to sight in 3" high at 100yd. with the ammo you are using.
The .358 Norma will do nearly anything the longer .375 H&H will do and in a standard length action.
The warmth of wood and individuality - something traditional hunters simply hate to trade off.
The "name "Sun Lion" was used to describe the receiver crest on the Persian Mauser made by F.N in Belgium.
The inner shock wave from brake escape flows back and assaults your eardrums and may eventually result in hearing loss.
The .32 Special barrel would stabilise the heavier bullet and would also be better with cast bullets because of less rotational torque.
Even a heavy roundnose bullet from the .458 Win. Mag, will be deflected by twigs and light branches.