Pet loads for 300 Weatherby

richbug

Since the nice weather is here I thought I would settle in and find a nice load for my 300. I fired 90 rounds today in 15 groups of 3, overlapping 2 times for a 6 shot group. I used H4831, RL22, and H1000. 150 gr Grand slams, 180 sierra BTSP, 190gr MK's, 180 speer BTSP, and 180 NP.

Nothing shot as well as the handloads that I had, but they were showing pressure signs in the heat, and I didn't feel like pushing my luck anymore. Groups were anywhere from 2.5" to 8". The old handload was doing about 1", but the new load data from hodgdon reduced the max charge by 6 grains, the old max charge was accurate, but definately showing some pressure.

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JustC

is it a weatherby rifle? if so, the long throat wil command more powder than non-wthby barrels without freebore. If you take a look at the begginning of your load data pages in the manuals,.you will see that they list the barrel manuf, twist, and length. If the rifle used for testing is NOT a wthby, then the charge weight will be greatly reduced due to the lack of freebore. I know sierra and nosler both use match grade barrels which I am almost sure are cut with reamers that DO NOT include freebore, thus the charge range has to be reduced. If you have a wthby barrel,..you may need to jump up in the charges.

FWIW, my pard shoots a tight necked 300wthby in 1000yd matches and he is using the 190SMK with rl25. ( Quite a few groups at 3-4" at 1000yds with that combo)

why chase the game when the bullet can get em from here?....
Got Balistics?

richbug

It is a weatherby MK5. 26" stainless light sporter. The old Hodgdon data was definately showing pressure, flowing primers, and a tighter than normal bolt. I will push the envelope a little with RL25 and see what happens.

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Ray B

I'd think the barrel has the standard amount of free-bore, but you might want to have a cast made; or what I do is take a fired case, size it just enough to chamber and grip a bullet, then put a flat-base bullet, upside down into the caseneck, just enough so that it will be gripped. then slowly and gently chamber the cartridge. The bullet base will contact the rifling and as the cartridge is pushed forward, the bullet will be pushed into the case. When the cartridge is completely chambered, open bolt, withdraw cartridge. The distance from case throat to bullet base will indicate the amount of free bore.

richbug

I found two loads that are shooting .7" or better groups at 100. Thanks for digging up this old topic. The one that really supprised me was a 150 grain grand slam on 80 grains of H4831. I shot Three three shot 1/2" group with it yesterday. Not really fast at 3000 FPS, but it should do for local Whitetails.

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