257-300 Weatherby LOAD DATA

[legolas8]

I have a German MarkV chambered in the wildcat 257-300 Weatherby, 26 inch barrel. Does anyone have any load data , especially with Hammers ? Thank you

[BB340]

Wow that thing must be screaming fast! I don't have any load data for you, but I am interested in finding out the ballistics you get from it.

[Dino82520]

When I'm stumped by lack of loading data for a wildcat that has no published data is to find another case and caliber as similar as possible. In this case you are lucky, the 6.5 X 300 offers a lot of data. I would take a particular bullet weight and compare it to the 6.5 X 300. Take the starting load for that bullet weight, reduce it by another 5% and you have a starting load for your .257 X 300. Take your time using all the tools you have at your disposal. A good chrono is indispensable. A good Micrometer to check expansion at the base is required. Keep an eye on your primers for excessive flattening as well as the case head for any flowing.

As always when sailing uncharted waters, take your time and keep notes. I you come across something that doesn't look right, BACK OFF! Common sense and good loading practices are the watchword.  Good luck on your first quest in the wide world of wildcats. I hope others will join in and suggest any thing I may have overlooked

The watchword is BE SAFE.

[legolas8]

Im not sure how to reply to individual posts as there does not seem to be a "reply " app but for this quick reply one ? At any rate I had a guy by the name of Bob Shell who did custom reloading load me a few boxes of 100grain GS custom Bullets with the teflon coating. They averaged 3980fps . BUT he passed away and when I had a guy pull some of the ones I had left , he said the Powder in there was NOT the REL 26 he said it was and he did not know what powder it was. I want to try the 93 grain absolute Hammer slug. it's hard to believe no one has any loading data for this. Weatherby himself said he shortened the case because the powders he had were not slow enough for the capacity back then on the full-size case with the smaller calibers under 30 .With the slower powders we now have it seemed more people would now see what it could do. The 6.5 does not shoot bullets that light that I know of for data and a larger bore would also even slightly decrease the pressure I would think. Hoping to find even ONE person who has tried this and can tell me some info. Thank you

[224KING]

I would look at 120gr loads for the 6.5-300 and like Dino said,back off 5% of the starting load for that powder you are looking to use in your rifle.

[BB340]

Hey legolas8 if you do find some data and get to do some shooting with it, could you stick around and put up a post showing us your data, velocity etc.?