Loading for 300 Win Mag

[retrieverman]

What twist rifling? If 165 grain is optimum I could spare you a few 165s to try. I think I have some 165 SGK, 165 Hornady Interbond, and maybe some 168 SMK. The SMK shoot really similar as the 165 SGK but aren't recommended for hunting.

They kill stuff dead dead though.

The twist is 1:11 which I think 1:10 is more standard. I appreciate the offer on the bullets, but I’ve got a bunch of 30 cal bullets yet to try. I’m really hoping to find a load using the 165 gr Corelokts. They shoot great out of my 308.
I just measured the chamber, and it’s 3.482 to the lands. Next I’m going to try the same load with a 3.48 OAL and see what happens.

It won’t be today though, because it’s FLOODING here right now.

 

[retrieverman]

I’m going to try a 180 gr Accubond load tomorrow with 67 grs H4831sc, CCI 250 primer with a OAL of 3.583. We shall see....

 

[retrieverman]

I shot the 180 gr Accubond load and got an 1.5” group with 3 of the 5 almost touching. It’s better but still not satisfactory. I’ve never had a Blaser barrel I couldn’t get to shoot one ragged hole at 100 yards, and that’s the benchmark. I won’t accept less.

I’m going to try a couple loads with 7828 next and see what happens.

 

[Okie4570]

What velocity are those running?

 

[retrieverman]

What velocity are those running?

I don’t have a chronograph, but according to the load data, I think around 2800fps.

 

[Cowbaby]

First thing I noticed is you have that thing laid out there, You stated 3.58 but your measured lands was 3,48 unless its a typo. That will leave you crammed against the lands and if its not crimped in might be seating slightly when you close the bolt. Some guns actually like this though.
Before I gave it up I would try a seating depth with a little jump to the lands and maybe shoot a ladder of half grain increments to find a sweet spot. Sometimes you can just put a different or mag primer in and it does better. But, usually those CCI 250s do well.
Me personally, I would probably grab that can of 4350 you mentioned and try some 165 and 180s. That powder is amazingly consistent in a broad range of things I have tried. And try a spitzer flat base first. You don't get any meaningful advantage from a boat tail until after 300yds anyway. Sometimes guns including mine just like flat based bullet.
Just some thoughts trying to help. You will find it, I know you will.
I am heading to the range myself tommorrow same caliber(and others), I have found a load but now just tinkering with OAL slightly before I crank a bunch out. I borrowed the neighbors shooting sled as I just had a 6x6 block of wood and a coat jacket last time, Plus I need to check for pressure problems in warmer weather with the stuff I am using just for safety sake before I do a bulk loading.

 

[retrieverman]

First thing I noticed is you have that thing laid out there, You stated 3.58 but your measured lands was 3,48 unless its a typo. That will leave you crammed against the lands and if its not crimped in might be seating slightly when you close the bolt. Some guns actually like this though.
Before I gave it up I would try a seating depth with a little jump to the lands and maybe shoot a ladder of half grain increments to find a sweet spot. Sometimes you can just put a different or mag primer in and it does better. But, usually those CCI 250s do well.
Me personally, I would probably grab that can of 4350 you mentioned and try some 165 and 180s. That powder is amazingly consistent in a broad range of things I have tried. And try a spitzer flat base first. You don't get any meaningful advantage from a boat tail until after 300yds anyway. Sometimes guns including mine just like flat based bullet.
Just some thoughts trying to help. You will find it, I know you will.
I am heading to the range myself tommorrow same caliber(and others), I have found a load but now just tinkering with OAL slightly before I crank a bunch out. I borrowed the neighbors shooting sled as I just had a 6x6 block of wood and a coat jacket last time, Plus I need to check for pressure problems in warmer weather with the stuff I am using just for safety sake before I do a bulk loading.

The difference in OAL is in the difference in a plastic tipped bullet vs a more flat soft point.

 

[Cowbaby]

Oh Ok. The ogive is different. I get it now.
I ran into this myself just today tinkering with some Federal 30-30 bullets. I can already tell I dont like them. About 1 out of 5 would seat to a different depth.
I'm getting pretty crabby about quality control in my old age and if it don't come in a green or black box or say sirocco on it I am already sceptical.

 

[retrieverman]

The first load with IMR4350 and 165 gr Corelokts didn’t produce any better results, and I’m going to Jen Psaki that one and circle back around to it later. I’ve had good luck with everything I’ve loaded with 7828 and am going to try it next. My success rate with Varget on other cartridges has been 100%, so it’s on the list to try too. We shall see...

 

[retrieverman]

After stepping away from this project for a while, I tried another load this afternoon, and it got the results I was looking for. 70 grs IMR4350 and 180 gr Accubond crimped at the cannelure got a 3 shot cloverleaf at 100 yards.
I’m still planning to try 71 and 72 grs just to see what happens, but it appears I was either pushing too hard or the inconsistent neck tension was causing my accuracy issues.