Reloading the 300 weatherby magnum

sport22

Active Member
Joined
Apr 26, 2002
Messages
26
Location
Sweden
Hi goodfellas!
I might buy a Weatherby Mark 5 rifle in a couple of weeks. The caliber is 300 weatherby magnum. The gun is used, but appears to be in very good contition. All factory parts. Left hand model.
If anyone here has got some experience with this caliber please let me know of your favourite bullet, seating, etc.
Myself I have only experience loading pistol ammuniton. Is there something extra important to think about when it comes to magnum caliber realoading?
Thanks guys and gals.
Warm greetings from a sunny Sweden.
/Emil
 

Delta Hunter

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Joined
Feb 18, 2002
Messages
161
Location
Mississippi Delta
The .300 Weatherby is my favorite rifle cartridge. I think you'll enjoy it. If I had to pick my favorite load it would probably be the following:

Powder: IMR 7828 (84 grains)
Brass: Norma
Primer: Federal 215M
Bullet: 180 grain Swift Scirocco
OAL: 3.56"

I have also had luck with other powders such as Reloder 22, H1000 and H4831. However, IMR 7828 seems to work the best in my rifle. I hope to try some Norma MRP and Ramshot Magnum soon. I am especially interested in the Norma powder.

I have tried various bullets and have had good results with just about all of them. As far as accuracy is concerned, I've had my best results with the Swift Scirocco, Hornady SST and Nosler Ballistic Tip (both 165 and 180 grains). I've also had surprisingly good accuracy with the Speer Grand Slam and Hornady Spire Point. The Nosler Partition, while an excellent game bullet, has not been so accurate for me in this cartridge. I prefer the Swift Scirocco to anything else because it's accurate, has a high ballistic coefficient and is stoutly constructed.

Since Weatherby rifles are freebored, I don't think varying the seating depth of bullets will have very much of an impact on accuracy. It hasn't for me at least. However, I have found that concentricity does seem to matter. I use a Lee Collet neck die to make very straight ammo that is remarkably accurate.

Good luck with the .300 Weatherby. You'll like it.
 

sport22

Active Member
Joined
Apr 26, 2002
Messages
26
Location
Sweden
Thanks!
I am very interested in your coice of bullet.
I will look into it.
Tell you about it later!
If someone else likes the caliber, please let us know your favourite bullet/load.
/OneShot
 

alaska

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Joined
Feb 1, 2010
Messages
754
Location
North Pole
Reloader 25 is also a excellent powder in the 300 Weatherby

My choice of bullets is the 180gr Nosler Partition or Swift A frame.

Fed 215 primers in WBY brass
 

1blacktail

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Joined
Jun 30, 2011
Messages
81
I've had my markV for 20 years it has a 26 inch barrel I shoot rl 22 with 87 grains with a 180 accubond 3405 fps it's very hot but that's we're it shoots the best, I am in the process of looking for a carbon fiber barrel and stock and make it my pack in gun, You will not get much life out of your brass primer pockets stretch after a couple of loadings. I also seat my buulet just to fit the mag because of weatherbys free boring
 

lloydsmale

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Joined
Feb 5, 2012
Messages
991
the best load in mine is a 180tsx barnes using re25 and a fed match mag primer. Im not a huge fan of barnes bullets but my 300wby is a finiky gun that is typicaly a 1.5 inch gun at a 100 yards and this load goes well under an inch for 5 shots and has dumped every deer ive shot with it.
 

john300wbymag

New Member
Joined
Mar 30, 2017
Messages
2
I am new to this forum as of today and would like to know if any one has develop a load for a Germen Weatherby 300 Mag. This gun has a 12" twist and a 24" barrel with a Mag Na port muzzle brake. I have been using Barnes 180gr TTSX factory shells grouping 2" pattern. I do reload for 257 wby mag & 7mm Rem mag with very good results. The 257 mag groups .25" & 7mm groups .50". I am a hunter, not a bench shooter but I want my hunting rifles to shoot like a target rifle because it give me the confidence shooting 400 yds plus. I have always kept my German Weatherby 200 yds or closer due to the large grouping shooting large game. I would appreciated if some one can guide me in the right direction with this rifle. Thank You
 

cape cove

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Joined
Mar 17, 2016
Messages
595
Location
Canada
I have never loaded for a 300 Wea mag,but I would think that your 2" groups may have to do with your bullet choice. The Barnes 180 gr ttsx is a long bullet and has only marginal stabality with a 1/12 twist. Your SG would be appx 1.10 according to the Berger program, and full stabality comes at 1.5. A shorter 180 gr bullet may give you the accuracy you are looking for, or a lighter one.
 

john300wbymag

New Member
Joined
Mar 30, 2017
Messages
2
Thank You cape cove & jfseaman. I will work up loads based on your advise. I have lately used Barnes bullets in this German Weatherby for Elk, Moose, Black Bear with excellent results for penetration and quick kills with 95% bullet retention on the ones that I could retrieve or did not go thru the cavity. I have been reading up on the Nosler Acubond and may try that if I do not have any success on the Barnes bullets. I have been using 4831 for my 257 Wby and 4831 or 4350 for my 7mm Rem mag. I will start with those powders first since I already have them and go from there. I want to try and see if I can get this rifle to perform better first before I decide to purchase another rifle that shoots MOA out of the box. Its been with me a long time and has a lot of memories. I have took a hard look at the Weatherby 300 mag Accumark Range Certified that could replace my Germen Weatherby. Again, THANK YOU for your help.
 

alaska

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Joined
Feb 1, 2010
Messages
754
Location
North Pole
I too have a German 300 WBY
With the 1-12 twist the 3 bullets in 180gr I have had the best luck with
are the Speer Grand Slam, Swift A Frame and the Nosler Partition Protected Point PP. All these are short enough to satablize in the 1-12 Twist.
A lot of good powders mentioned already but the new Reloader 26 is a great start.
For game up to elk the Barnes 150gr TSX kills like lightning in the 300 wby.
 
Last edited:

MudRunner2005

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Joined
Oct 13, 2008
Messages
14,708
Location
Alabama
Try IMR 7977 powder as well. I have a .300 Ackley, which is essentially a .300 Weatherby Improved, and with 7977 (on a ridiculously hot and humid day) I was getting an SD of 7, and an ES of 14 FPS. That's one of the most consistent powders I've ever used in a big magnum cartridge on a day with conditions like that.
 
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