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.
300 wby pressure signs
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lloydsmale
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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.
backwoods83
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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.
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?
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
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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.
thanks.
i am using this info from the net.
Long-Range Load Development
my first step is to determine max load.
accuracy comes in when you do the ladder and find the sweet spot.
im just trying to find my max and work back from there to find the spot.
all the data iv looked at was maxed out about 3 grains ago. lol.
iv got about a .130 thou run at the lands before contact.
should i be using a longer, heavier bullet so it can get closer to the lands or is the extra wby freebore ok with most bullets?
i am using this info from the net.
Long-Range Load Development
my first step is to determine max load.
accuracy comes in when you do the ladder and find the sweet spot.
im just trying to find my max and work back from there to find the spot.
all the data iv looked at was maxed out about 3 grains ago. lol.
iv got about a .130 thou run at the lands before contact.
should i be using a longer, heavier bullet so it can get closer to the lands or is the extra wby freebore ok with most bullets?
backwoods83
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- Jan 8, 2011
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- 3,414
My match wbys only have .060" freebore, not the .360" avg a mk5 has, so no not all bullets work well, stick with SMKs and Amaxs. I had a 270wby that I always ran 6.5grns over book with no pressure in sight and great accuracy. Most data for wby cartridges is very conservative in case someone is loading for one that doesn't have the "standard" wby freebore.
update.
i loaded up 15 more and maxed out at 84 grs. first test was 82 grs. then .5 gr intervals. i got one with an extractor mark and one of the 3 was just a tad hard to open so im right on max at 84 grs. of imr 7828. case stretch at belt was .516". now i can load up some at 83 and down to start my ladder. i chronographed them all and got an average speed from the 3 shots at max load of 3075 fps. thanks fellas!
i loaded up 15 more and maxed out at 84 grs. first test was 82 grs. then .5 gr intervals. i got one with an extractor mark and one of the 3 was just a tad hard to open so im right on max at 84 grs. of imr 7828. case stretch at belt was .516". now i can load up some at 83 and down to start my ladder. i chronographed them all and got an average speed from the 3 shots at max load of 3075 fps. thanks fellas!
