I have a 458 SOCOM and loaded up a bunch of 350 Gn. round-noses over a moderate powered load. The profile of the bullet hits the lands and won't chamber when seated to the deepest seated cannalure. What should I be aware of if I want to push these bullets back until they seat? (0.050" or so)

Many thanks.

It's impossible to predict. Crowding the powder space increases pressure, increasing the bullet jump reduces pressure.

If you tell me which powder, bullet, and COL (longer and shorter) I can check with Quickload 3.2; it could be useful.

COAL: 2.062"
RL-7 37 gn.
Hornady 350 gn. RN PN 4502
Seated about 0.444"
Case length 1.57"

Your load seems to be too hot, over 36200 psi (Pmax 35000). Of course it's only a guess.

I forsee no problems doing what you propose with moderate loads.

Using medium or slow-burning rifle propellants, the bullet is usually at least 4" or so down the bore before maximum pressure occurs, and it is much better from a pressure standpoint for a bullet to get a slight "running start" before having to be engraved by the rifling.

For example, it is possible to fire some pretty oversized bullets in a rifle with no ill effects as long as the bullet can easily move forward out of the case into the chamber throat. Problems occur when the case won't let go of the bullet as pressure rises in the case.