loads for 30-378 weatherby

mudd_boggermudd_bogger Member Posts: 75 ✭✭
can anyone give me some loads for the 30-378 weatherby magnum. im shooting 165 grain nosler b/t. want loads to run in the 3500-3550 fps range an be accurate.thanks to all of you that respond. have agood one an safe shooting


  • nononsensenononsense Member, Moderator Posts: 10,645 ******
    edited November -1

    Welcome to the GB forums!

    I've been shooting this cartridge along with the .338-378 for quite a while now but I don't bother with the lighter bullets since they are usually a waste of time and materials in my applications. I start with 180 gr. bullets and go heavier.

    You don't mention what you want to use these loads for and this can be important simply from the standpoint that the Ballistic Tips don't usually stand up to these velocities on impact. They work when shot at lower velocities but not at the velocities you mention. The other problem can be the length of barrel that you are using. If it's factory, 26" isn't nearly enough in my opinion unless you choose to really push the safety range of peak pressure. The article below reinforces my opinion of needing 30" in order to achieve the velocities and maintain proper pressures for safety. Otherwise you're just wasting powder.

    I know it's not much but without more information, we have to start somewhere. The last link below has some loads for the 165 gr. bullets.


    Weatherby .30-378:

    The Big Dog

    Unquestionably, the .30-378 is the big dog of midline rifle cartridges. Its huge case has the ability to hold well over 120 grains of powder, and that is a hearty appetite. This cartridge is formed when the massive .378 Weatherby parent cartridge is necked down to .30 caliber, maintaining the trademark Weatherby double-radius shoulder. The .30-378 was developed for 1,000-yard benchrest shooting, but it has its place as an ultra long-range deer cartridge. It has also proven itself as a long-range elk round; with the proper bullets, it is capable of taking any game on the North American continent.

    We have found that our rifle produced far different results than what has been reported in other gun magazines. Part of that is likely due to the difference in rifles. Much of the previously published data was developed in custom rifles built for the caliber before Weatherby brought it out as a factory item. Differences in lead and throats may make much of this data suspect and unacceptable for factory-chambered rifles. Also notable is that loads which showed no pressure signs in our rifle when tested in 20-degree weather last winter (with velocities below 3,300 fps) were much too hot when shooting in 70-degree temperatures.

    Most of our .30-378 shooting has been with reloads, since a limited amount of factory ammo has just came on the market in July. After experimenting with a variety of powders currently available to the handloader, we have found no truly safe handload that can deliver the factory-spec 3,450 fps with a Barnes 180-grain X-Bullet. Most of the loads we built that approached the factory velocity left the gun's bolt difficult to open. Those that exceeded 3,500 fps were dangerously over pressure. In our Weatherby Accumark rifle, the most velocity we could safely achieve has been 3,300 to 3,350 fps, which still ain't too shabby.

    A small sample of 40 factory rounds we recently received shows the .30-378 does indeed approach 3,450 fps, depending on the gun and conditions. (Handloaders aren't able to duplicate this performance safely because the company's technicians have access to powders and blends of powders that are not available to the reloader.) Nonetheless, based on our testing, we believe those shooters who think they can buy a .30-378, load the rounds with light bullets, and propel them at ultra-fast velocities for deer and antelope are probably going to be disappointed. Based on the data we've collected so far, we think it will be difficult to get top velocities in guns with barrels shorter than 30 inches. You will also burn a lot more powder and suffer more recoil to do it.

    However, this cartridge starts to come into its own with bullets heavier than 180 grains, particularly 200-grain bullets. We have a handload that uses H870 powder and a 200-grain Nosler Partition bullet. With a muzzle velocity of 3,230 fps, it averages 0.75 inch at 100 yards for three shots.


    Here is a website built on reloading for the 30-378 Weatherby:


    Some loads featuring the 165 gr. bullets:

  • mudd_boggermudd_bogger Member Posts: 75 ✭✭
    edited November -1
    thanks for the info. have got some numbers today off the chronograph that realy blow my mind. the rifle that im using has a 28 inch barrel. loaded up 3 bullets with different powder charges an never seen any signs of preasure problems. the first load was with a 113 grains of retumbo got 3468-3490-3485 fps with 1.5 inch group. tha second was with 114grains of retumbo 3518-3525-3528fps with1.5 group. now this is where the numbers started to come together. load#3 115grains of retumbo with 1.25 inch group 3590-3600-3608. the next load worked the best from my rifle beleave it or not. the max load of retumbo 116grains with 1 inch group 3678-3672-3665 fps. all of these loads where within the specs that hogdon powder recomends an there was no pushed back primmers an the bolt opened freely each time. so to everyone that says the factiry stuff can not be copied well look at my first load the factory stuff came across at 3452-3446-3471with the same group size of 1.5. an the temps today where in the middle 40s about the average for hunting season here in maine, but the next warm day in going to try the load again to see if we start pushing primmers.
  • nononsensenononsense Member, Moderator Posts: 10,645 ******
    edited November -1


    The testing quoted and the article were generated in about 1999 prior to the development of Retumbo. The barrels used were factory and limited to 26" as supplied. Yours being 28" should be a custom although the factory website states that use 28" barrels as standard.

    "an there was no pushed back primmers "

    Are you talking about judging pressure by the flattening of the primer in a Weatherby case?

    Have fun but be careful.

  • mudd_boggermudd_bogger Member Posts: 75 ✭✭
    edited November -1
    thanks nonsence. for the info. yeah im judgeing the preasure by looking at the primmers. is that wrong? i have never loaded for a weatherby before this is my first one that i have owned. just always looked at primmers on all other stuff that ive loaded for,so i hope that i can still look at them to help me out.so please let me know anything else to look for i dont need to kill myself or junk out my rifle. thanks
  • buk-masterbuk-master Member Posts: 5 ✭✭
    edited November -1
    Hello their I'm building a 30-378 Wby with a 30" Douglas Barrel with a 1-10 Twist What kind of performance will I be expecting out of it What will be my max Range and how will it perform. I have never shot one but hoping it will do the job. I want to use it for hunting mule deer in flat land and from canyon to canyon. What kind of bullets should I load and also if any of you guy have brass E-mail ma at [email protected] Thanks
  • nononsensenononsense Member, Moderator Posts: 10,645 ******
    edited November -1

    Since the GB forums are owned and operated by Gunbroker Auctions, offers to buy, sell and trade are not allowed on the forums. Please edit your post.

    "What will be my max Range and how will it perform."

    These will all depend on your ability and practice first and foremost. If you can't shoot at 600 yards, it's hard for us to say you should be able to shoot at 1,000 yards. It will also depend on your loads and choice of bullets. My suggestion is too look at some reloading manuals and maybe the data that's on the internet to see if you get a better idea of what you will being doing in the first place.

    Here are a couple of Ballistics software packages, one free, one for a tree trial to help establish some of your information:



  • perry shooterperry shooter Member Posts: 17,390
    edited November -1
    Hello MUD-BOGGER please don't take this the wrong way but I have a friend that was getting some very high velocity from his hand loads in a 204 Ruger when we went the range with 4 different Chrongraphs we got a wide range of values on the same shot . we lined up the units to shot one shot through all 4 at the same time if his was the closest or last one from the muzzle it read 10 % faster then the other 3 . I am just saying you might want to check with another unit.
  • pissnpits4upissnpits4u Member Posts: 1 ✭✭
    edited November -1
    First check out conley precision cartidge web site. You would have to guess at the powder and ammount.
    In any sport, you evaluate what you want to win and how bad.

    My deer to elk gun is a Marlin 1895 with a Simmons aetec scope and it will bring down a moose at 300 yards with the new hornaday shells. I am totally happy with this. I am limited to wooded areas here. I have yet to miss with this gun. One to one shot to kill.

    I own the Weatherby for target ranges up to 1000 yards. I like the .308.

    I was shooting a 30-06 moved to a winchester 300 mag new barreled and converted HH, then a remington ultra, and now the 378.
    I can go to a full 120 grains of retumbo, launch a 155 moly at 3800 ft per.
    I had a ton of various size .308 bullets to play with and am spending the winter loading up some test rounds that I can chrono out this spring. I will reply back with the best data I can.
    I talked to quite a few long range shooters and the 30-378 is the hands down choice for target, the 338-378 is the choice for hunting up to 600 yards. This is comparing the two weatherby rifles only.

    My old rifles where a trial and error process that led up to the 30-378. Each one allowed higher velocities and less drop at distance.
    The 378 case allowed best choice and wieghts of bullets, with the widest range of powder selections. I read hundreds of articles prior to buying this rifle, needles to say many were against the 30-378 for price of ammunition, and barrel life.

    I like 116 or 117 grains at 1000 yards. About 3640 ft per. Again retumbo powder and a boat tail hornaday 155 molly

    I am now getting a custom stock for long Range and will plan to replace the barrel with a heavier 30 inch, counting the brake. I want to to try a slightly slower powder with this 2 inch extension.

    I am in no way able to outshoot the factory sponsored boys, but each trade off I have made is getting me closer.
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