303 trouble

[gerrycan]

Hey all,had some mixed reults at the range yesterday.About 10 shots gave high pressure signs[hard bolt lift flat primers and marked headstamp area ].The 315 Lee X 185grs gc were loaded over 13 grs Red dot or 16 grs Unique [AP 70 in Aus.] .I finished of some jacketed ammo loaded with 49 grs. w748 they went great.
So any ideas why the cast loads didn,t play nicely in my P14 ?

[Yodogsandman]

Loads were too hot.

[Calamity Jake]

What kind of high pressure signs?

[JeffinNZ]

Those loads are fine. Have you pushed the case shoulder back?

[fatelvis]

What diameter were the jacketed bullets? Have you slugged the bore?

[gerrycan]

I haven,t slugged the bore,but .315 should cover it.The jackets were .312 I guess and no I didn,t push the shoulder back,must be too hot load ?

[braddonovan67]

It could be the shoulder needs a little nudge back, or too much powder. I'd guess powder. Unless the trim length is all wrong. Check that too.

Sent from my SM-G900W8 using Tapatalk

[runfiverun]

something was pushing the pressure up.
the nose jammed into the rifling or the case not being able to let go of the boolit.
high pressure signs are high pressure signs.
the red-dot load Is already at 45-k of pressure when things are a little sloppy it wouldn't take too much to push it even higher.
between that and the 303 actions max pressure your in the too much zone.
drop it down 3 grains and try again.

[44man]

Use rifle powder! Cast can take the slower pressure rise and more then you think.
Stuff 4350, Varget or 748 behind your boolits. 3031 might be good and 4895.
Darn you have a Brit, not a .38!

[Bulldogger]

Try chambering and ejecting the loaded rounds to see if they are embedding in the rifling or just barely seating.

Are the cases well cleaned? If case lube is still on them, they might not squeeze and grip the chamber walls, allowing more than usual pressure backwards to the case head.

Speaking of grip, are the fired brass hard to resize? .303 chambers can be very generous, which would make it hard to get good case performance, especially if the brass was new or if you are full length resizing cases being sent into a loose chamber.

I suppose you know these things, but thought I'd offer them just in case.

Bulldogger

[Kraschenbirn]

31.5 gr. H4895 under that same Lee boolit produces 2045 fps (10-shot avg.) from my Longbranch #4Mk1 without any hint of over-pressure. ( 37.0 gr. of IMR4350 yields just about the same velocity with a slightly lower SD but, right now, I'm more abundantly supplied with 4895 than 4350. )

Bill

[gerrycan]

Thanks for all replies,dully noted, Gerry.

[bruce drake]

both of the cast loads are fine pressure wise. There is something else going on.