Home Forums Reloading Big Game Rifles 30-378 & 338-378 weatherby

I just signed up on this site. I have a couple of Weatherby Accumarks one 30-378 and one 338-378. I have been working up loads for these and my friends 30-378's over the past few months. I wanted to share/trade information with any of you that are reloading these calibers or have other information you would like to discuss...Thanks JJS

Have an Accumark 30-378 and have tweaked up mollied 180 Noslers to about 3,470 fps with H. 870. Am away from my records here, so I am not listing specifics. Like most of my life, if I figure out something is worth using, they quit production within a year. The powder is no longer available unless it's left over on someone's shelf. I have about 5 cans, but given the case volume, they won't last long. Would be interested in any loads you have that give similar velocities and reasonable accuracy. It's not a rifle that I take to the range for fun, but when it does come out, it's serious business. 1Minute

1min,

You might want to think about trying Retumbo in your 30/378.
I shoot it in my 300 RUM and it works awesome with 180 and 200 Accubonds.

The 300 RUM isn't quite the 30/378 but it is close enough in case capacity that it might work as well in the big Weatherby.

Tony.

SUCKS 700 bdl, 28" bbl, 338-378 have had nice sub 1.25" 200yd groups with about 105 gr of RL-22 under 185 Barnes xlcbt. Don't have all the figures here in front of me... The heavier stuff is 250 gr Partition Gold over about 102 gr of H-1000. I think my gun needs some tweeking, the higher charges won't shoot as well as the lesser charges do. If you get to the 250s with a full case it does have just a bit of a bark & a bite to go with it <img src="/ubbthreads/images/graemlins/cool.gif" alt="" />

Pat

This load has been a super load for my 30-378 Wby Accumark.

Bullet - Barnes Triple-Shock 180 Gr. .308
Powder - RL 25 106.0 Gr.
Primer - FED 215
CL - 2.900
COL - 3.770
3425 FPS
.5"

I have tried lots of bullet, powder, primer, COL combinations and this one has been a shooter for my rifle.

Al

Is AA 8700 the same as Hodgdon H870 ?

Hammer

Here is some information about these two powders. You can look at the loads listed on their websites and decide for yourself.

H870 - This spherical powder is great for heavy bullets in big, overbore magnum loads. H870 is also used in the 50 caliber BMG and is the only surplus powder left in the canister line. Because it is inexpensive, it is frequently used in large capacity cases where economy is a major consideration.
Available in 1 lb. & 8 lb. containers.

H870� AVAILABILITY - As of July 15, 2002, Hodgdon Powder Company will no longer offer H870 powder. As most who read this will know, H870 has always been a military surplus product. The United States Military is no longer using this product so there will be no availability of fresh surplus. We would like to warn you that some powder sellers may try to sell you some form of military surplus powder and claim that you can use our H870 data. This is simply not true. What they are selling will most likely be some slow burning powder but it will not conform to the burn speed of H870. Do not be fooled. If the seller cannot supply data specifically for his powder, it is untested and the burn speed is unknown. This could lead to a dangerous situation resulting in damage to property or injury to shooters and bystanders. If it does not come from our bottle, with our label, it is not a Hodgdon product.
http://www.hodgdon.com/smokeless/rifle.php

8700 Our slowest burning powder is a double base, ball propellant that is best suited to the magnum rifle cases such as the .257 Weatherby Magnum, .264 Winchester Magnum, .270 Weatherby Magnum, 7mm Remington Magnum, and .300 Weatherby Magnum. 8700 may also be used in cartridges such as the .25/06 Remington and .270 Winchester (velocity and pressure will be reduced from normal, but accuracy is outstanding). Interestingly, it performs well in a large variety of cartridges for cast bullet loads. Use of a magnum primer is recommended for best results.
http://www.accuratepowder.com/data/8700.htm

Thanks for the imformation. After much trial and error we have developed very accurate loads in both the 30-378 and 338-378. The load for the 30-378 has been tested extensively in 3 different rifles and basic information is as follows:

Norma/Weatherby case trimmed to 2.903
Powder: Retumbo
Primer: Federal 215 Match Grade
Bullet: Barnes Triple Shock 168 grain

This load chornographs at a nomial 3500 fps with extreme velocity spreads averaging 10 fps. Accuracy at 100 yds is better than 1/2" depending on which rifle and who is shooting. This load produces sub minute of an angle out to 700 yds (longest distance shot at so far). I shot a 4" goup at 700 yds with the help of my Swarovski TDS which really works great!

In the 338-378 same basic info. except using 4831sc. and Barnes 185 grain Triple Shocks. Load is nominal 3460 fps chornographed. Produces 1/2" 100 yds and is sub minute of an angle to 600 yards (longest distance tested so far).

Other info. which is helpful. I swtiched my dies out to Forster Ultra Die Sets and Forster Co-Ax Press and have seen signifcant improvement in run out and most importantly at the range. If anyone once further detail I will gladly supply in private e-mail...just let me know by posting on site...Thanks again...JJS

Highcountry: Thanks. Wrote the Retumbo into my book and will go that route when the H870 runs out. I should be good for a couple years as the Weatherby doesn't go to the range for recreational shooting. Take care, 1Minute

1min,

I know what you mean. These big 30 cal boomers aren't for plinking soda cans on a Sunday afternnon.

I have just worked up an awsesome 200 AB load for my 300 RUM using Retumbo and Fed 215s. I will be using that combo on an upcoming mixed bag hunt in BC this coming Sept. Unfortunately no grizzlies are on the menu, otherwise I be using Partitions. However, moose is on the menu and it should be a good test of the AB.

I have bunch loaded up for practice, under field conditions, up to 300 yards (max at the ranges I have access to), so I will be burning up some Retumbo this summer. I feel comfortable shooting out to 400 - 500 yards (max) if it becomes necessary, as I have previously taken elk at over 400 with the 300 RUM.

Tony

JJS,

I have found that Retumbo gives very uniform results in terms of no velocity variation due to changes in termperature.

I shot my pet Retumbo/200AB 300 RUM load over several weeks this past winter, in a temperature range of almost 40f (20f to 60f) and found little to no velocity change over that temp range.

Accuracy was outstanding. Very pleased with the results.

Tony.

hicountry and 1 minute:

Appreciate your feedback. We have found the same as to Retumbo being stable a varing tempeture at least from 30F to 75F. Will do some shooting in the next couple of months so we will see how it does at 90+ and then up in Canada middle of November -15F or so (however will be hunting so will not have my chornograph with us).

Have you guys had any trouble with movement in scope rings? I have and recently switched out all my rings and bases to Talley (Screw lock rings). This seems to be an improvement over what I was using.

Thanks, JJS

JJS,

No problems. I am using plain jane Leupold 2 piece bases and rings, the type with the windage adjustment on the rear base. I have a Leupold 4.5x14x40mm on my 300 RUM. Not a very heavy scope. I would bet that the heavier scopes want to move under the recoil of the heavy recoiling guns (simple momentum).

I had thought about going to dual dovetails, but I have never had my 300RUM or 338 RUM (Leupi 3.5x10x40mm) for that matter, shift POI or have the scope shift. I am shooting both my 300 and 338 RUM's with this settup, without a muzzle break, so the mounting system and scope are getting the full recoil.

I may however, eventually switch my 338 RUM to Leupi dual dovetails, only because I intend to use it on big bears up in Alaska. Don't want to leave anything to chance.

Tony.

JJS: The only unit I've had scope travel with is a 257 Weatherby with a B & L Elite 6-24X, a fairly long and heavy scope. Tigtened rings to no avail. Shimmed inside with aluminum foil to no avail. Put masking tape around scope adjacent to rings, put a light bead of silicon seal around scope, screwed together, removed tape to take off seal leakage, and it has not moved since. With just the bare rings and shims, the movement was actually shearing the exterior finish off the scope. I have pulled another scope that I gave identical treatment to, and it was no problem getting things apart. Good luck. 1Minute

Hi JJS,
I have a couple of recipes that my 30-378 Accumark seemed to favor if you ever want to try some heavier bullets: As everybody always says, work up your own and IMO the ladder works as well as any to get in the ballpark.

All with Fed 215 match primers.

103 H1000 200MK, 118 H50BMG 200MK, 106 Retumbo 200AB, 101 RL25 220MK, 115 H50BMG 220 MK, with the accuracy preference going to the Retumbo Accubond combo. This was before I learned of bullet sorting, measurements, etc. Have since found the AB to be very consistent out of box bullets which was reinforced in the targets. These were with initial ladder tests at 300 and then comparative group testing at 3 to 800. If I had limited testing to 300 the H1000 200MK combo would be my choice. But now I get to do it all over again because I transformed it into a McMillan swirly machine. I never tried light bullets as one of my future goals is some extreme range shooting.

I use the Forester bench seater, Redding S neck bushing dies, and all the tricks that may or may not make a difference. Never considered a micrometer top for this one. Didn't figure 3/8 inch or 3/8 inch and .005 would make much difference. My COL is just where I can eject a live round.

I'll look you up for some note comparing later if and when I ever rebarrel, I'm thinking long 338 next time.

Shummy

I'm running a fairly mild load in my 338/378 but accuracy is good and it gives more than enough punch for anything I'm likely to shoot
100 grs H4831/250 gr Nosler Partition
Averages about 3020fps

No! One is from Accurate Arms and one is made by Hodgdon. Use only the data listed by each separate manufacturer for each respective powder to work up loads.

Took me 5 years to get accuracy with the .30-378WBY(450 rounds).I was using Rcbs dies with no accuracy,almost every cases f/l sized with the sizer were "crushed below the shoulder,crushed in spots"( the sizer was adjusted 1/16"before touching the shell holder.The roundes had no accuracy 2.5MOA with some flyers.Someone told me to switch to Forster bench rest dies,makes a lot of difference,no more crushed cases,f/l sizing was smooth compared to using strong strengh with the rcbs.Redding f/l dies set didnt work fine,the same problem with rcbs.Federal 215 primers were too hard to seat,I had to enlarge socket pocket hole,I switch WRLM.I have to glue bedding srews,they didnt stay tight.The load is H-4831sc(102.5grs),Hornady 150grs interlock,trim 2.900"C.O.L.3.665",primers WRLM.The rifle can shoot accurately now,easyly under 1".The .338rum,I have difficulty with the base mount,the front one didnt hold,I have to glue it,the bedding is ok...

Wow! you had some real issues to work through. Have been using RCBS neck sizing dies on mine with no problems. My unit did start eating the Leupold scope mount system though. I switched to Talley mounts and now have about a 1/2 minute unit. Also, had some hot weather pressure issues and had to drop back to 118 grains of H870. Haven't chronied it since I dropped back, but accuracy is still wonderful. It's been good for 1 moose, 3 caribou, and this year's elk. An awesome chambering indeed. 1Minute

I tried 121grs H-870,(180grs bullets) very too hot load,drop back to 116grs.H-1000 107grs(max),I tried 11grs a lot to hot.H-50bmg 120 grs(I tried 121grs(hot).I am using H-4831sc (102.5grs)150 grs bullet.Rcbs neck sizer dies,no good accuracy with it,may be the seater was not that good.I enlarged the muzle break by 1/64".I have mount problem with the .338RUM,the Leupold mounts,front base wont stay tight;the two rear bolts (base)dont stay where they should be...