Rookie 300 Wby load development woes...

[Falfreak]

Newby here posting with a first post. I primarily reloaded for revolvers throughout the year but the last few falls I find myself loading belted magnums with varying degrees of success.

I am seeking some load development help for my hunting rifle. It's a Remington 700 that has been re-barreled with a factory 24" Remington 300 Weatherby barrel. I do not know how much free bore there is and assume it is minimal because I am getting solid extractor marks and a sticky bolt with factory 300 Wetherby 180 grain ammunition.

Previously, I had loaded 20 rounds consisting of 77 grains of IMR4350 behind a 180 grain Sierra Game King but I did not record to OAL and I shot them all up before I was able to shoot less than a 2" group.

Since then, I have developed a load consisting of the full length sized once fired (in another rifle) Weatherby brass, CCI 250 primers, 180 grain Horandy Interlock boat tail bullets and RL-22 powder. I have RCBS dies and plan on only neck sizing once all brass is fire formed.

I used Dan Newberry's optimal load weight development instructions and found that with the bullet seated to the bullets caliber's depth into the case. Grouping was better the hotter the load but around 82 grains but I had flattened primers, extractor marks and a sticky bolt. So, I backed the charge down to 81 grains without changing anything else. Flattened primers and slight extractor marks are still showing so I am planning on backing the load back and trying 80 grains and 80.5grains.

I am wondering how my seating depth could be effecting accuracy and want to adjust accordingly when trying the lighter powder charges. I adjusted my seating die out and loaded a dummy round out past maximum magazine length. With the bullet cleaned with steel wool and black marker on it, I carefully inserted the dummy round into the chamber and closed the bolt. I could not see marks from the lands. So, I loaded three rounds a little shorter at maximum magazine length.

My father who has been loading for his 300 Weatherby since I was a kid, suggests that I trim all brass to length and use a light roll crimp even though it would not line up with the cannalure on the bullet seated to this new depth. I tried this with three cartridges charged to 80.5 grains but observed some shoulder deformation from inconsistent case length.

Now, I am re-thinking my approach and looking for advice before I load the 20 or so pieces of brass that will serve as my test loads. These vary from 2.813" to 2.825" in length. The reloading manuals I have referenced suggest a trimmed length of 2.815" with a maximum length of 2.835".
Once I load and shoot these I am going to go with the best performer, load the rest of my brass for hunting season and go confirm my drops.
Is a crimp necessary? Should I load with neck tension only and see if I get bullet movement?

Any suggestions on seating depth and pressure associated with changing it after developing a powder charge?

I do not shoot enough to notice the accuracy gains of spending massive time wringing every little bit out of a load but I would like to get a load developed that shoots 1.5 MOA when I do my part. I do not have a choreograph. Any suggestions are appreciated.

 

[MagnumManiac]

OK, the Weatherby chamberings have a long throat, to check, hold rifle muzzle down, drop the bullet you're using into the chamber pointy end first and chamber an empty case behind it. Extract the case, if it comes out with the bullet in it, measure with calipers, if it doesn't come out with the bullet in it, then you have a standard Weatherby throat.
I own several Weatherby's, I load to max mag length, if they shoot I leave it, if they don't, I seat DEEPER until they do. I go in .005" increments.
If you are getting ejector marks, REDUCE THAT LOAD AT LEAST 3%.
I don't care how flat or not your primers are, but ejector marks are BAD. It may be soft brass, but Weatherby brand brass does not like hot loads and is soft.
This may be caused by your throat if it's short, but more likely it is just an overload.
I liked RE25 in mine when I had a 300 Weatherby.

Cheers.
gun)

 

[gohring3006]

If you have at least .308in. Of bullet bearing surface seated in the neck then I wouldn't crimp. I'm with MagnumManiac and would back off away from ejector marks your ruining your brass..
What bullet are you using? If it has a canalure I would seat to that maybe you have to much air space in the case. I seem to get better accuracy when I don't have a lot of space between the bullet and powder.

 

[300WineMag]

I looked in the Sierra reloading manual and they dont list 180 game kings for 300 wby. The other 180 gr bullets listed shows 70 gr min ( 2900 fps) to 74.8 gr max (3100 fps) with h 4350 so you have a hot load at 77.

At 2900 fps a 300 wby will smoke any animal in N America with a good hunting bullet, so I would start at low powder and stop when you find accuracy and don't worry about speed unless you are hunting at 700+ yards.

I start low and add .5 grains in 3 shot groups and maybe fine tune in smaller increments around that load once an accurate powder weight is found. Wait as long as you can between shots, and let the gun cool completely between 3 shot groups as 300 wbys get hot barrels in a hurry and the accuracy goes away then. Weatherby loads need to jump so don't try loading to the lands. Sierra lists 3.56" max coal, Barnes is 3.39 min, 3.56" max.


I shoot 78 gr of h4831sc ( 76.5 gr min, 83 max) with 180 Barnes TTSX at 3.56" coal and get .5 - .75 moa out to 500 yds in a Blaser R93 as a hunting rifle and load. I never crimp any rifle loads for target and hunting in bolt guns.

Good luck, hope this helps.

 

[Dosh]

Fal, your brass needs to all be the same exact length, if it is tight in the chamber bump the shoulder in small increments till it fits well. Although IMR 4350 can be used, perhaps it is a little on the fast side. Try 300 Win's H4831SC or a slower powder being sure to start low and work up. Lose the crimp. Then you can start playing with seating depths after a charge is found to work for you. No 2 rifles like the same load, powder or seating depth. My son's 300 Wby likes H1000, but his pal's likes H4831SC both with the 210 Berger. Good luck Load safe

 

[Lefty7mmstw]

I'd use 7828 or slower and keep going up in bullet weight until the thing shoots well. My buddies 300roy didn't settle down well until we shoved 220-225 grain hpbt's in it.

 

[Deleted member 46119]

What Lefty7mmstw said.

IME: IMR7828 is 'the' goto powder for Wby's. Others can work but....

IIWM:
Exploit the freebore.
Get some bearing surface into the free bore.
Distance to the lands guidelines.
All the normal stuff.