Today i shoot my 303epps with new loads,
last i was pushing the Gods got 2803 fps with 180grn highland sp bt but 1 out of 5 shots blown primer load was 53 grn S341, similar to ww760, ball powder from Somchem.
Go back to S 365 , same than imr 4350.
54grn 180grn higland spbt, velocity 2765fps.
load 52grn S355, burning rate near imr 4320, 150grn hornady sp, 2958fps both loads print sub moa.
Proof wat Acley ond Epps said 303 Imp 303 came near origial 300 H+H factoyy loadings

Are you using the Mk. IV?
Pressure sounds a bit much, as you're getting 30-06 velocities out of a smaller case.
If it works for you and you feel safe, great! I however question, for myself, velocities out of proportion to case capacity. (unless you use Hornady Pixie Dust)

quote:

Originally posted by 303epps:

. . . but 1 out of 5 shots blown primer load

That right there should be a big clue and wake up call.

I've done this wildcatting (blown primer) before. You're in the 70+ kpsi pressure range.

That is why I stopped loading S341 ballpowder, similar than WW760, pressure to high!!
Use Winchester cases and Federal 210 primers.
Rifle is a P14 with Musgrave barrel, extra metal in chamber area.

Try some H4831 you should get lower pressures .If it was mine I would be trying some 7828

For what it's worth, here is what QL has to say about your loads.

Again for what it’s worth, QL thinks the following powders are too slow if you feel the need for speed.

Thanx for the QL imformation! We are handicapped
with powders, can only get Somchem powders.
Why I load the 303 Epps in the 2800+ fps is to use it in hunting rifle shooting competition, were we shoot gongs up to 350 meters, diameter 8 inch, I try to minimise my holdover, looking for flatter shooting. If I my ask what load recoment QL?

303epps, you have a PM.