Help with 30-378 load

Blackdirt Cowboy

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Dec 9, 2018
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Texas
I’m doing load development on my 30-378 and need a little direction on where to go from here. I’m using RL33 powder and 196 grain hammer bullets. I’m only shooting at 100 yards because it cold and snowy and that’s as far as I can shoot off my back porch. So far, I’ve done a ladder to find velocity nodes as well as pressure. Here is what I came up with on my velocity test.
055CBA63-3383-468E-B556-2B04B1F1DE36.jpeg


Looks like a velocity node down around 109-109.5 and another at 110.5-11.5. I was really hoping to find a higher node, but ran into pressure, so I stopped. Based on this information, I loaded up 5 rounds at 111 grains with a COAL just short of magazine length. Here is the resulting group.


49158087-D6BF-4FD1-B040-A04D0A7FC93A.png

I guess with that group, it would be an ok short range Texas deer gun, but I was really hoping to be .5 moa or better. My question is, will playing with seating depth shrink this group to acceptable levels or should I try a different powder? If seating depth is the culprit, which way do I move it, shorter or longer? I prefer to be shorter than magazine length as this will be a hunting rifle, but if longer is necessary, I’m ok with that. I just want to figure out the best course of action in order to use up the least amount of my supplies possible. Any advice?
 

GLTaylor

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Hammer Hunters are not usually very seating depth sensitive. You might try seating them .020 deeper (shorter) just to see if it makes any difference. I assume you're using Mag primers? How much neck tension are you using? Most like .003 for Hammers (or more).
Last resort, try another powder. N570 works very well in my RUM.
Good luck!
 

19Wyoming

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Sep 30, 2018
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Utah
How’s the trigger on that gun? What gun is it? Accumark.
Make sure that trigger is good to go. You can try .020 deeper. It may make a difference. If it wont tighten up, try other powders.
I use Federal LR Magnum Match primers.
 

Blackdirt Cowboy

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Federal 215m primers. Neck tension is .002-.003. It is an accumark and the trigger has been replaced with a timney 2lb break. The action has been bedded as well.
 

Aoudad shooter1975

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I take it your COAL is 3.79...I struggled with 2 accumarks. I found they did better with bullets in the 165-180 weight range seated at 3.69 or standard OAL...they need a pretty good jump to shoot good--so you might need to seat your bullets back a bit.. I tried a whole slew of 200, 215, 230, grain bullets and had group size hover around 1.2-1.5 inches.. shoot 180 interbonds--just a smidge under a inch...i finially set the barrel back and cut it into a 300 Norma... it shot 3/4 in groups with 212 ELDs all day long after that. I had fair results with Retumbo and 869 with mine...Hope you find the awesome sauce for your 30-378--Stay warm!!!
 
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rml30378

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Central WI
Not knowing how many rounds down the barrel , that is a respectable group for a factory Accumark. When I bought mine Weatherby’s guarantee was an 3 shot group of 1 1/2” @ 100yds. If your hunting with that rifle I would load that load and go hunt. You will burn that barrel out searching for 1/2 minute group. After 600 rounds I tossed my barrel and went with an 28” 8 twist cut rifle barrel and its shoots way better. Another thing is RL33 will turn your barrel into a coal mine , I clean every 50 rounds.
 

CMDR Kibo

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TexCoMo
I shot this cartridge in a Weatherby Mark V Accumark. My "accuracy" powder was H50BMG, 118 - 118.5 gr, for around 3,333 to 3,350 fps (at altitude) with 180 gr bullets (Scirocco, X-bullet, A-frames, Partitions). I kept the trigger stock but lightened it all the way down. My best groups ran at 5/8" at 100 yds. I had the COAL stretched out around 3.815, IIRC.

I tried other slow burning powders (H1000, VV N170 & 165) and could get more velocity but not more accuracy. I don't believe I ran Retumbo through it. I have no experience with the Hammer Hunters. Perhaps try seating the bullet further out and a different powder. With the better trigger you have in there, I would expect that you can get those groups tightened up reasonably well.
 

lancetkenyon

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Arizona
1:10" twist? Probably too slow.
Just finished a .300WM pushing the 199 HH, but it had a 1:8", and was a cloverleaf gun with 4 different charge weights of H1000 and 2 different consecutive seating depths @ .030" & .040" jump.
 

David Emerson

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Drayton,ND
You might have a slightly oversize barrel. I would try WLRM primers. They are the hottest primer there is. Also try crimping in the first groove. Hammers work well crimped for me. Failing that try some sierra 200 GK just to see how they shoot. Now I hate to dump in your cheerios but I have never seen an Accumark that gave stellar accuracy.
 

fishonnw

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May 19, 2009
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Eugene, OR
I ran in problems with this cartridge. Thought I had it good with 225 eldm’s at 200, went back to 650, and the gun shot all over the place. Decided to start over and checked many bullets and found I could get a 208 eldm .020 off and still fit in the mag box. They shot great. I am using retumbo. Rl33 did not shoot well in mine. The bullet might be too light to make it work. The point is that I was dead set on a bullet, and found sometimes you just need to switch it up to be successful. This season I shot a cow elk with the gun at 725 this season. Dropped her in her tracks.
 

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