Reloading the 7mm Dakota

[Hawk in WY]

I'm developing loads for my Dakota Model 10 in 7mm Dakota with a 1:9 Lilja barrel.

Wanting to shoot Barnes bullets at long range.

The 168 gr. LRX with 72.5 gr. IMR 7828, Fed GM215M, go into a half inch but sideways. 7828 SSC actually but that shouldn't make a difference.

I live at 6,200 feet and hunt at 7,000 to 10,000.

Clearly I need to drive these bullets faster.

Since there is little published data, I put this project on hold.

A ladder test of Barnes 145 gr. LRX from 73 to 75.5 gr RL-22 with 0.5 grain increments had everything around 1.5 inches.

I took the 75.5 grain load and varied the COAL from 3.33 to 3.45 (.020 off the lands) and got a one inch group at 3.35. I can and do shoot better than that.

Time to increase powder charges until I see pressure, change bullets, powder?

All advice much appreciated.

 

[bruce_ventura]

...I live at 6,200 feet and hunt at 7,000 to 10,000. Clearly I need to drive these bullets faster. Since there is little published data, I put this project on hold.

Higher MV will help a little, but not much. The stability will improve with range, but the large angle of attack on that wobbling bullet in early flight will degrade BC. That defeats the purpose of a higher BC bullet. Higher altitude will help, but the colder air temperature during fall and winter will hurt. Check the twist rate of your barrel. It may not be 1:9.

A ladder test of Barnes 145 gr. LRX from 73 to 75.5 gr RL-22 with 0.5 grain increments had everything around 1.5 inches. I took the 75.5 grain load and varied the COAL from 3.33 to 3.45 (.020 off the lands) and got a one inch group at 3.35. I can and do shoot better than that. Time to increase powder charges until I see pressure, change bullets, powder? All advice much appreciated.

Copper bullets like a long jump. Try .050-.070" off the lands.

 

[Hawk in WY]

Thank you for the reply.

I measured the barrel as 1:9 or a little more. Lilja tells me they don't do fractions. They claim 1:9.

Berger's stability index says the 168 grain should be stable, but the LRX is a very long bullet. I am shooting at 6,200 feet. The group with the 168 is fine if it wasn't key holing. I wasn't seeing pressure signs at my top load, but the scarcity of published data makes this difficult.

I ran the COAL range with the 145 gr LRX from SAMI spec of 3.33 which may not be far enough off the lands. I will redo the COAL measurement to the lands. My measurement seems short when I think about this.

Any one have a bullet/powder combination that shoots in this caliber?

Thanks in advance.

 

[AZShooter]

If the 168 LRX is keyholing it isn't being stabilized. Do you feel you need to stick with a monolithic style bullet? Nosler and Hornady make their versions. Guess you could try the 145 LRX. None of these have good BCs which IMO has to be considered when shooting longer distances.

I chose to use the 168 Berger Classic hunter BC .604 in my 7mm/375 Ruger which I believe is a ballistic twin to the 7mm Dakota. (this is not the 7 LRM)

I found RL-33 worked the best for good accuracy and high velocity, 86 gr for 3268 fps.
from a 26" barrel.


A friend shot his cow elk with the 168 classic hunter from a 7 Rem mag, at just over 3100 fps at the muzzle and remarked it was the fastest kill he had ever had on an elk.

 

[rickiesrevenge]

I don't use those bullets in either of my 7 dakotas. I've used the 162 AMAX, 175SMK, 180VLD, and 180 hybrid. With the 162 AMAX I use H1000, 180Hybrid Ive been running Retumbo but have been playing with RL33. RL33 is quite a bit faster across the chrono. If it were me I'd switch bullets to a bullet with a lead core. I've only had a couple guns that shot the all copper bullets really well.

Aaron

 

[Hawk in WY]

Thank you for the reply.

I really like the Barnes bullets. Good BC and good terminal ballistics in my experience.

I'm afraid you're right, however: Time to switch bullets.

Where do you find published load data for H1000, Retumbo or RL33?

Is there a way to get a starting load from 7mm STW data, for example?

I love the idea of the 7mm Dakota but this is proving harder than it should be.

Any experience with 7mm Dakota loads much appreciated.

 

[longrangehunterII]

Berger Bullets reloading manual has data for the 7 mm Dakota. For their 168 grain bullet you were a over their max load of 68.8 grs. using IMR-7828 SSC, which in most cases the Barnes bullets tend to use less powder being a monolithic bullet to achieve the same pressure.

7 MM DAKOTA 168 Match VLD Target, Match VLD hunting
H4831 SC 62.0-67.5
RL-25 65.5-71.1
RETUMBO 70.0-76.0

They have a few other powders listed but not H1000. I'd find a bullet that the barrel likes best, and go from there. Question, is the contour of the barrel thin and does it have 3/4 rib and front sight attached to the barrel? Either of those can cause some issues with what to expect from the rifle accuracy wise that I've found that can happen with both in a barrel.

 

[Hawk in WY]

The Berger manual is one I don't have.

Those data are very helpful. Thank you.

The 72.5 grain IMR 7828 load for the 168 grain Barnes LRX came from careful study of the data in the Hornady Seventh Edition where it is well below max for 162 and 175 grain bullets.

I also found an older article from Barnes, possibly from an earlier manual, which indicated 72.5 grains should have been below max.

The latest Barnes manual does not have 7mm Dakota data.

It felt on the warm side but no obvious signs of extreme pressure.

If I try 7828 again, I will use the Berger data.

What does the Berger manual say for 150 grain bullets? I'm looking for a Barnes 145 gr. LRX load.

All input much appreciated.

 

[Hawk in WY]

Question, is the contour of the barrel thin and does it have 3/4 rib and front sight attached to the barrel? Either of those can cause some issues with what to expect from the rifle accuracy wise that I've found that can happen with both in a barrel.

No front sight, but thin barrel and a sling stud on the barrel 3/4 of the way up.

I was allowing the barrel to cool between shots.

Not using a sling.

I don't like sling tension on the barrel but this is apparently a trademark of Dakota rifles.

 

[longrangehunterII]

Berger only has a 140, 168, 180 bullet in their manual.

Berger 140 VLD hunting
H4832 SC 66.0-71.8/3175 FPS
IMR 7828 SSC 67.0-73.1/3253 FPS
RL-25 69.5-75.8/3261 FPS
RETUMBO 74.0-80.5/3237 FPS

 

[Hawk in WY]

Success!

First of all thank you to all who helped enormously with data I did not have.

The Berger data looks conservative and is well below other published sources, but was very helpful.

I now have three loads which will put the 145 gr. Barnes LRX bullets into just slightly over one half inch, 73.5, 74.0, and 74.5 grains of RL-22. Fed GM215M primers. 3.40 COAL (.060 off lands).

Normally I would now fine tune the powder load and play with COAL but since the 74.5 grain load put five into .364, I'm done.

No signs of pressure, but the absence of published data made this more difficult that it needed to be.

Barnes needs to update their reloading manual.

Will run this load over a chronograph in a few days and stretch it out to 1,000.

I will return to 168 gr LRX load development when I'm done with this load.

Now what some might not agree with is what else I did to make this fine rifle shoot to my satisfaction.

I pulled a bullet because I thought seating required more effort that normal.

Found the new brass and the once fired brass tumbled with pins was shaving the sides of the bullet.

Chamfering the case mouth and adding a bit of powdered graphite to the inside of the neck got this rifle shooting.

I realize there are many variables here, but in future I will be chamfering the case mouth of new Dakota brass and either dry tumbling after wet or using graphite on the inside of the necks with either new brass or "squeaky clean" brass from wet tumbling with pins.

Hawk heading for cover.

 

[IanCo]

Any updates on loading for your 7 Dakota from the last few years? I am searching for Barnes LRX info and found this thread.
I've had a 7 Dakota for about a year now and have to estimate starting loads with the newer powders.

 

[Hawk in WY]

Interesting to read this old thread.

I'm one of those reloaders who lets perfect be the enemy of the good.

Fine tuning never ends.

Here's what I have learned in the interim:

1. My nine twist barrel doesn't like heavy bullets. I have gone to a .300 Win Mag for elk and use the Dakota for pronghorn.

2. I no longer wet tumble with steel pins. I believe, rightly or wrongly, that carbon in the necks is a good thing.

3. My elegant looking but easy to carbon foul brake may have been the cause of the instability with long bullets. I now clear the brake thoroughly every time I clean the barrel.

4. I have gone to VV N-570 for no good reason other than my rifle likes it. Barnes 145 gr LRX, 83.4 grains N-570, fifty thou off the lands for 3,474 fps out of my 24 inch barrel. Pronghorn hate it. I suspect I will be seeking a new barrel soon.

5. I really like the external and terminal ballistics of the 7mm bullet but will never again buy a rifle chambered for a round where Lapua, ADG, or Petersen doesn't make the brass and for which published data is not broadly available.

Keep us posted on your load workup. Good luck.

 

[IanCo]

I did finally make it to the shooting range yesterday to try out some new handloads.

First loads were Nosler 160gr Accubonds on top of IMR 7977. I started at 74gr and went up to 77gr in one grain increments. I played with this powder with the 175gr LRAB and Partitions already so was pretty confident in the charges for my rifle. Had one ok group, one awful group, one good group and one great group. The good group had an ES of 2 and the great group had an ES of 30 I think. The last group at 77gr did give me some sticky bolt lift.

The 168 gr LRX I shot over 8133 and I started at 71gr and that was too light as I had a couple with sticky bolt handle. I went up in half grain increments to 73gr and wasn't getting into any accuracy nodes yet. Had another group with ES of 2, all the groups were ok but I know it will get better with some more velocity.

On a side note I did shoot a steel plate at the beginning of every group for a fouling shot since I clean the barrel each group, and I recovered two LRX's that had probably 2/3 of the bullet intact. After seeing that I am pretty sure I am going to work hard to make that my hunting bullet.