300 wby pressure signs

[axe3761]

i have been working up 3 different powders for my 300 wby mk v action 30 inch barrel. im using h4831sc....imr7828....Hercules reloder22. max loads that i have done so far are 75gr...78gr....76gr. respectively. i am testing 220gr. sierra hpbt mk's. im worried about missing max limit by not catching high pressure signs before its too late. i have taken some pics of the case heads so you can look at them and tell me if im getting too close. primers appear to be getting flattened but bolt opens easily and no extractor marks...at least i cant see any. primers appear a bit cratered also. federal 215 magnum primers are being used. i know what im looking for but im not seeing it yet and the manuals i have are maxed out....should i continue till i see something drastic.

[lloydsmale]

those look fine to me. I guess to me i look at brass life. If you push the weatherbys to hard youll get loose primer pockets after one or two loadings. If that happens i back them off a bit. I figure if I get 5 loadings out of a peace of brass im in a good ball park.

[CliffM]

Mine gives me a definite shiny spot from the ejector with Rem. brass as the first visible sign. I find measuring case head expansion to be the most reliable indicator.
Cliff

[slee]

My 3oo bee always flattens primers no matter the load.

[backwoods83]

Weatherbys can be tricky to find pressure, but the best way was already mentioned, use your calipers to measure case head expansion right in front of the belt, don't let it get more than .006" bigger than factory spec. 75grns of H4831sc shouldn't be hot under a 220, but I don't know your chamber dimensions or OAL, but I have went up as far as 75.5grns of Imr4350 under a 208 while chasing thhe throat in and Imr4350 is way faster than 4831sc. Flattened primers in a wby is no big deal case design allows this to happen even when they are not maxed out, and your primers look fine, they're not really even flat. Also for accuracy and low ES with the 3 powders you listed I would back down to CCI BR2, Fed210m, or WLR primers, no need for 215s with those loads.

[axe3761]

thanks fellas!
i did some more testing and picked imr7828 as the powder im gonna use for now. i loaded up 15 more rounds with 81 gr. as the max. i measured velocity at 2975 fps average between 3 shots. case dimensions just ahead of the belt measured .515" factory spec is .512". primers look ok and no extractor mark. bolt was easy to open and accuracy was good. coal is 3.720" max coal with this bullet is 3.850". should i keep testing for max or should i be happy with aprox. 3000 fps?

[backwoods83]

At 3.850" oal you have room to go yet to max, probably 83-83.5grns. Try to get the best accuracy and extreme speard, then worry about the speed.