7mm WSM with hornady superformance

[corbin9191]

Hey guy's, I thought I would share my results with you. I recently picked up a pound of the Hornady Superformance powder to try out. I have been looking around for some reloading data for the 7mm wsm but could never find any. So I started out really low and worked my way up. Started out at 57 grains and worked up from there. I went to the range today and got to chronograph a few loads (Started to rain so had to leave). All these loads are with Winchester nickle brass with CCI BR-2 primers and a 168 grain Berger Target VLD at a OAL of 3.013"

65 grains- 2972 FPS
66 grains- 3151 FPS
66.5 grains- 3112 FPS
67 grains- 3148 FPS
67.5 grains- didn't read any
68 grains- 3219 FPS

Crony was set at 15 feet from the end of muzzle

After that the loads started getting hot and I started to see ejector marks and the primer really stated to bulge out. These loads are from a Winchester model 70 with a 24 inch barrel.

 

[DrMike]

Those are smoking, for sure. Though it is a blended powder, I have to wonder what sort of pressures you are generating.

 

[corbin9191]

I am wondering what type of pressures I am running as well. Although there are no pressure signs, is there a way to see what types of pressure I am running?

 

[DrMike]

Whilst it is not out of the realm of reason that you will generate higher velocities due to the pressure curve being spread over a longer interval with sustained pressures holding for a longer portion of that interval, 300 fps above what would normally be projected is higher than I would anticipate. The standard signs for pressure are brass flow, incipient case separation, etc. You will want to maintain a watch for these signs to be sure. What would interest me would be the condition of the primer pocket after a couple of firings. That observation is of necessity, somewhat subjective; but it does give some indication of excessive pressure. Alternatively, if you have access to a blade micrometer, look for case head expansion at the web. Whilst the technique is considered to be unreliable in isolation, it is a reasonable indicator of pressure provided you hold all parameters to the same standard. The easiest and most precise way to test pressure is to find a shooting buddy that has an Oehler Model 43 Personal Ballistic Laboratory. It probably wouldn't hurt to speak with one of the techs at Hodgdom just to get their feedback.

 

[corbin9191]

I will keep a close eye on all of those things. At the moment the Oehler Model 43 Personal Ballistic Laboratory is out because I don't know anyone around here that has one. I just called Hodgdon powders and they did not have anything to say about it. They said if I am not seeing any pressure signs and the accuracy is there then that is good. But There is only a few cartridges that they have this information available for. I just thought it was a little strange to see the bullets going that fast and not have any pressure signs.

 

[Guest]

I'm thinking of a couple of things offhand. First off, I suspect the Berger has a relatively short bearing surface, thus a small bearing surface area. That will help you reduce pressures and increase velocity because the bullet will tolerate a higher charge of powder. So I'd consider the velocities not quite as dramatic as Dr. Mike, though still of some concern. The main thing I notice about them is the consistency from 66-67gr (velocity is virtually unchanged across that range), which tells me that's the ragged edge of the pressure curve for this round. What you're seeing at 68gr is probably pushing 70kpsi or better. I'd like to see some once-fired cases blade mic'd before and after their second firing. And I'd prefer they be once fired with a mid-weight charge of some known standard powder, like H1000 or Accurate MagPro, to set the case head expansion pretty well. I bet you're getting something on the order of .0005-.0007" expansion, and I also suspect (as I think Mike does) that your primer pockets will be loose after another couple of firings.

If it were me, I'd drop back to the 66gr load if it's accurate and call it done. Then I'd still do some mic'ing if I could, just to be sure. And I'd watch those primer pockets. If you lose the brass to loose primer pockets after less than five firings, I'd back down another grain or so. That's just my take. Use whatever you like from it.

 

[corbin9191]

I'm thinking of a couple of things offhand. First off, I suspect the Berger has a relatively short bearing surface, thus a small bearing surface area. That will help you reduce pressures and increase velocity because the bullet will tolerate a higher charge of powder. So I'd consider the velocities not quite as dramatic as Dr. Mike, though still of some concern. The main thing I notice about them is the consistency from 66-67gr (velocity is virtually unchanged across that range), which tells me that's the ragged edge of the pressure curve for this round. What you're seeing at 68gr is probably pushing 70kpsi or better. I'd like to see some once-fired cases blade mic'd before and after their second firing. And I'd prefer they be once fired with a mid-weight charge of some known standard powder, like H1000 or Accurate MagPro, to set the case head expansion pretty well. I bet you're getting something on the order of .0005-.0007" expansion, and I also suspect (as I think Mike does) that your primer pockets will be loose after another couple of firings.

If it were me, I'd drop back to the 66gr load if it's accurate and call it done. Then I'd still do some mic'ing if I could, just to be sure. And I'd watch those primer pockets. If you lose the brass to loose primer pockets after less than five firings, I'd back down another grain or so. That's just my take. Use whatever you like from it.

I am going to go back to 66 grains because I am not sure about the pressure. But I just thought I would post the results up so people could look at. I will be measuring some brass to see what is going on with them. But 66 grains is the charge that I am sticking with.

 

[Guest]

Sounds like a plan.

Don't misunderstand me, either. I think what you did was responsible and safe. I do things the same way. Plenty of homework, plenty of safety, working up slow, and stopping when you got signs. I just think that when velocity plateaus, it means pressure is at the ragged edge of safe, and after that, things can get dicey quick.

I think you'll be very satisfied and very well served by that load at 66gr.

 

[DrMike]

Good call, dubyam. I was reading fast and didn't catch the plateau. I focused on the final chronographed load, which is pretty dramatic. With H1000 or MagPro and 168 Berger, I'd anticipate velocities in the 3000-3050 fps range.

 

[SJB358]

Wow, that is pretty awesome. 3150 with a 168gr bullet in the 7WSM in a 24" tube is smoking. I would be interested in seeing what it does also. I think 257 Ackley plans on giving the Superformance a try in his 6.5WSM when it comes in. It will be interesting to see what it does in that also. Those readings he got could have been misreadings also. Meaning, unless you have a few shots to see what it is doing, I have shots do odd (readings) things through the chrono once in awhile also. Nice to see what 3-4- or 5 of them are doing.

It will be nice when QL catches up with it. I always feel much safer seeing the data backed up and not having to use a bunch of guess work to get there. Mikes data he ran for me and the 264WM was pretty accurate and really helped me tune in to where I wanted to be.

I wonder what the burn speed of Superformance comes in at? Is it like a Retumbo, MagPro, or the like? Scotty

 

[corbin9191]

I wonder what the burn speed of Superformance comes in at? Is it like a Retumbo, MagPro, or the like? Scotty

I called Hodgdon powders and the guy told me the burn rate is just a touch slower than H4831.

 

[corbin9191]

Good call, dubyam. I was reading fast and didn't catch the plateau. I focused on the final chronographed load, which is pretty dramatic. With H1000 or MagPro and 168 Berger, I'd anticipate velocities in the 3000-3050 fps range.

My normal load is with H1000. I am getting 3114 fps.

 

[DrMike]

Hodgdon lists the burn rate as being between Supreme 780 on the slow side and H4831 on the fast side. I would expect that the burn rate is fairly sensitive to such factors as case volume and bullet weight. I note that the Hodgdon web site generally lists lighter for calibre bullets with this powder as they increase case volume.

 

[corbin9191]

Well just went to the range again and shot 2 three shot groups with the 66 grains. I am not very impressed. The best groups was around 1.75". I think I will just stick to my load of H1000 and a three shot group of .408" I can sacrifice around 40 fps for the accuracy :lol: I just thought It would be a cool idea to give it a try. I know that I could adjust the OAL but I will save my bullets and go back to the load that works well and has taken a deer at 652 yards.

 

[SJB358]

Hard to mess with that kind of performance! Can't beat the accuracy and speed you are getting out of H1000. Show us some pictures of the rifle and a target or two! Scotty

 

[corbin9191]

Hard to mess with that kind of performance! Can't beat the accuracy and speed you are getting out of H1000. Show us some pictures of the rifle and a target or two! Scotty

As soon as I can shoot more targets I will sure post up some pics of them. I will try to post a couple pics of the rifle as well today.

 

[SJB358]

Looking forward to them. That 7WSM is a pretty awesome cartridge. I really think Winchester is missing the boat not chambering their cartridge in THEIR darn rifles. Scotty

 

[DrMike]

I really think Winchester is missing the boat not chambering their cartridge in THEIR darn rifles,

As was/is true for the .280 Remington, the American shooting public is enamoured of the .277 bullets. To be certain, 0.007 inches doesn't seem like much; but I do enjoy my 7mm WSM and the remainder of the .284 calibre rifles that grace my safe. The 7mm WSM is a great cartridge. Sadly, I don't believe it will ever be a big seller, though those who own one seem content to hang onto them.

 

[SJB358]

Either one would make a great addition. I like both of them. I have a 7RM, and think a smaller 7mm would be a nice rifle. The 280 would be a nice one. I passed up a Rem Mtn rifle in 280 about 15 years ago. Had a Leupold 2x7 Compact on it. My cousin ended up picking it up and now I get it rubbed in my nose non stop! It shoots everything really well. Scotty

 

[Oldtrader3]

I have both a .270 Win and a .280 Rem and with deer hunting loads of bullets with the same sectional density (130 vs. 140), they are virtual twins. It is too bad that the .280 Rem was never pushed by Remington except for the early models (1959-1960) in the 760 and 742 rifles. Remington never did load this caliber up to its potential until after the 7mm Express fiasco. The real advantage of the .280 comes with heavier bullets IMHO. My .280 shoots 150 gr bullets better than the .270 shoots them for certain. If you handload, you can match performance better with the .280.

My problem is that I also have a 7mm Rem Mag which gets most of the play for long range mountain hunting. Despite this, I have never sold my .280 though.