Need some help guys.
Elk Hunt is scheduled in September. Pulled out my old seven mag, and was going to load some 160 partitions and H4831. It's a load I worked up years ago and is quite accurate and my rifle. But couldn't find any 160gr PTs, so I started working with some 150s.

Yesterday I found some 160s at a local LGS. Before starting to load with my old load I checked some current manuals. Somewhere around 60 grains seems to be the consensus Max. My old load was 68 grains. It was accurate. Velocity about 2950. Never had a problem.
Some of my old manuals have equivalent loads. What's up with current manuals and 160s with H4831?

I know current manuals are more conservative than the old ones. And I know JB says the seven mag is one of the cartridges with potential pressure spikes.

I'd Be interested in your thoughts. Should I continue on with my old load? Reduce the charge? Or start over with a different powder?

Thanks for yor thoughts.

68.5 Gr. of H-4831 w/ 160 Nosler Accubonds is a good one for our rifles @ just under 3K.68 gr. of IMR-7828 does about the same.

Tried RL-25 and always come back to one of the 2 loads above for velocity and accuracy.

Another problem with 7mm Remington Magnums is that for some reason throat length can be all over the place. It's not as bad as with some of the really old military rounds like the 6.5x55 or 7x57, but it's there.

Then there's the fact that H4831 isn't the same powder it once was. In fact there have been four different versions over the past 50 years: The original mil-surp powder, the made-in-Scotland replacement, and the two present Australian powders, the short-cut and "long-cut."

There have also been differences in 160-grain bullets over the past 50 years as well, not just in a wide variety of makes but differences in one make, such as Nosler Partitions.

My advice would be to work up while keeping a eye on the chronograph. Whatever powder charge results in around 2950 fps should be OK, though it's not impossible to encounter traditional signs of high pressure even at moderate velocities.

Thanks, John. Very helpful.

BTW. My load was worked up in the 90's. Would that have been the Scotland iteration of 4831, or the Austrailian? Thx.

To tell the truth I don't remember when they changed. All I really know is the change to the Scot-made powder was in the mid-1970's.

Ok. Thanks again for the help.

In my 26" barrel M70, I worked up to 64.5 gr with H4831 and was hitting 3000 ft/sec. At 63.5, my gun shot its best (1" group) and was ~ 2950 ft/sec.

As John said, the 160 Noz PT has changed over the past 10-15 years. They have a more sleek profile now than they did 10-15 years ago. I have a box of both and noted my OAL changed when I bought more. I checked them out and found the older bullet was 'squatier' than the present day version. I simply left the ogive measurement alone and they both shot nearly the same.

I also really like H4831 in 7mm's. It won't be the fastest but may be the most accurate and won't change much when it gets colder. I really like the Hodgdon trifecta - H4350, H4831, H1000. Throw in H4895 and I'm pretty well set for most cartridges. Most of my hunting guns shoot one of these 4 powders with a Nosler bullet. It works.

Southtexas: I want to recommend you stay with the Nosler 160 grain Partition bullets!
When this bullet is properly placed in the heart/lungs area of Bull Elk it is reliably lethal on them.
A few years back I shot a 6x6 Bull Elk right at 300 yards distant using this bullet, and that Bull never moved a step from where he stood.
He did not fall right away but he never took another step.
I have seen several Bull Elk killed with one shot by these 160 grain Nosler Partitions from 7mm Remington Mags as well as from 7mm Weatherby's!
And in my experience these bullets do very well on Black Bears also.
My 24" barreled Remington 700 Classic that I bought new in 1995 has only ever shot these bullets - and it shoots them very accurately - using 66.0 grains of H 4831 in Federal cases and Federal 215 M primers.
I have not been seeing any pressure signs but maybe I better suck up a dose of caution and re-check my loads?
Like you I am sure this loading was NOT book maximum back in 1995 when I started using it.
Better safe than sorry though - and maybe we better re-assess our loadings.
Best of luck to you on your upcoming Elk Hunt.
Hold into the wind
VarmintGuy

SouthTex, My advise when loading for the 7RM for the first time or when making drastic changes in bullets or powders is to go slow. For example my 7RM would blow primers with 68grs of H4831 and any 160gr bullet. I like IMR 7828 better than current H4831, but even with that slower burning powder 65grs and 160 Nos.Part. is maxed out, but velocity in my 26" Hart is 3050fps or so.

Thanks, gentlemen. I think caution is a good thing in this case. What is curious to me is the variation in max published pressures shown for the 160 grain/H4831 combo.

For example, the Hodgdon website shows 58K max for 7828, IMR 4831, IMR4350 and others. But for H4831, H4350, H1000, and others, the max pressure is about 50K. In fact the maximum loan for H4350 is 55 grains while the max load for the IMR4350 is 59 grains.

I am aware that there are lots of reasons why loading data varies. This just seems like more variation than is normal.

But I'm looking forward to the elk hunt, in spite of all this confusion.

The 7mmRM load data is a joke. It's been castrated by lawyer feared IMO. I use my chrono and check for pressure signs mapping my own loads. Following book loads will barely get you 280 rem velocities. A chrono is a must.

southtexas, BTW I've taken several bull elk( other animals too) with the 160gr NP and it is one great bullet. Plus, the 7RM despite it's challenges for the reloader is one of the best for western hunting of mule deer and elk. If you want to practice with a less expensive bullet, the Sierra 160 GK often shoots to the same POI.

Great thread fellas! Question, if my 7mag does well with RL 25@70gr and RL 22 @ 65gr, where should I expect H4831sc to be in grains? I bought some for my 300wsm but want to try it in my 7 mag as well.

Some of the down loading is reportedly due to the propensity of the 7RM to have wider than expected pressure variation in test barrels. So, unlike the 7 Wby and others, this round is SAAMI limited to lower pressure. Similar deal with the .243 Win. vs. the 6mm Rem.

Now, that should open a can of worms....

DF

I've heard of these mythical pressure variations before too.

My 7RM wears a new SS Brux, chambered and throated for 168 VLD's. I wouldn't hesitate to load it above the current pressure ceiling and let it sing. I do realize that the 7RM doesn't have Wby freebore and shouldn't be pushed to those velocities. But, it's a hunting rifle and I won't shoot it enough to erode the throat and set up the test barrel phenominon.

But those pressure variations did occur and the ammo/powder/bullet makers had no choice but to cover themselves with the revised SAAMI pressure cap. They couldn't assume that all 7RM's out there had new SS Brux barrels without advanced throat erosion.

DF

Makes sense. But doesn't explain why some powders are allowed to max out 10k psi higher than others. Are some powders more susceptible to pressure spikes? Surely there are not different SAAMI pressures standards for each powder in each cartridge.

The 50k for h4831 is cup not psi. That's why it's different. The max pressure in cup is lower. While I too find 7mm data to be sand bagged a bit a lot can change in 20 years. W 760 is not the same today for example. Use a chrony and work up.

SAAMI stds, are for the round. Each powder has to be tested to see how it acts and what load(s) will adhere to those standards.

We need to stick with powder company pressure tested data and not get too far off the reservation.

But, for the reasons mentioned, I would not hesitate to go with older, hotter 7RM data, knowing I had a new barrel. Nevertheless, I would cautionsly work up from current load data, using my chrony and watching for signs of a problem. As others have posted, powders change over the years and assuming too much can become problematical.

DF

You had me til "problematical". Now I don't know how much of it to believe.

Ahh...good catch. I. Missed that.

southtexas,

Dirtfarmer's explanation of the reason for the slightly lower SAAMI pressure standards for the 7mm RM is exactly correct. The pressure variations have been documented in many laboratories, many times, but can vary with powders and primers.

I was visiting a new pressure lab a dozen years ago when the head guy told me about the variations he was seeing with some loads. He'd called the head guy at the lab of a major ammo factory, and the other guy said, "Yeah, that's what happens sometimes in that cartridge!" (Members of SAAMI--the Sporting Arms and Ammunition Manufacturer's Institute--tend to cooperate with each other, since the whole point of the organization is to make sure handloading data and factory ammo works safely and reliably in factory rifles.)

Another problem was variations in chamber dimensions between manufacturers, especially when the cartridge was at its peak of popularity from 1962 through the 1980's. Various companies were really cranking out 7mm RM's, and differences in throats were common.

This doesn't mean the pressure variations happen with all loads, in all rifles, but SAAMI members don't want their customers blowing up rifles, or themselves--and not just because they'll get sued. SAAMI is an organization of VOLUNTEER members, who want their products to be safe. Injuring or killing customers isn't good for business.

MD: Thanks for all the intel. Interesting stuff.

I've got a good supply of IMR4831. May be a little faster than optimum for the 7Mag, but looks like I should be able to ease above 2900 fps without a problem, and that would be enough to suit me.

Sounds like a plan. Single-based powders like IMR4831 are generally less touchy than double-based powders that an produce a little more velocity.

In my loading manual, there is a caution regarding 7mm mag loads.

It says loads worked up in Norma brass must be reduced by 10% and worked back up if changing to different brass, this was due to variations in case wall thickness and case capacity.

In this manual it lists the top loads coming from RL 19 and RL 22

Nick Harvey's Reloading Handbook

I can get in the low 2900 's with H4831 & the 160 AB in a 280 AI and that IS NOT hot ridding the round.

Loading 160's in the 7 Rem Mag to about 3000-3050 or so fps in a bunch of 7 Rem Mags, a few thousand times the last four decades, has kept me out of any trouble with the cartridge.Never blew a primer nor had a hint of a problem and a few of those barrels were shot until they were worn out.

I don't reach for H4831 for the cartridge so much anymore,although it works very well with 150 gr bullets. 160's can start to get stubborn IME,and I like to start with slower powders for the cartridge these days once bullets hit 160 grains and up.

I load 160s at 3000, 150s at 3100, and 140s at 3200 generally. I've only been loading half as long as Bob but have also never had a pressure issue of any kind in 7RM. I'm usually a couple of grains over max to get these velocities. Most of my loads are slightly below max in older manuals. Using a chrono is a must working up max loads. My favorite powder the past couple of years for 160s is H1000.

Agree with Bob and Horseman. My fave/most accurate powder for 140,s, 150's, and 160's is RL22. Velocities in line with Horseman's experience.

I like H4831 in my 7mm Remington Magnum too but I ran out months ago. I've still got a pound of H4831SC but that's reserved for my .260 Remington. I've found IMR-7828 to be just as good as H4831 in my 26 inch Rock Creek barrel. Here's my hunting load (velocity 15 feet from the muzzle).

Bullet: Nosler 160 gr. Partition
Powder: IMR 7828 64.0 grs.
Primer: Federal 215
Case: Federal
LOAL: 3.285 (2.745 Base to Ogive with Stoney Point)
Average Velocity: 2919.70 fps
Extreme Spread: 27.44
Standard Deviation: 10.53

RL 22 works well also. My favorite round in the 280 AI is a 150 NBT with H4831SC just under 3000 fps. I have no desire to try and make the 280 AI into a 7RM.

Nosler 150 BT - 58.0 IMR4831 WLR 3043 fps
Nosler 160 AB - 57.0 IMR4831 WLRM 2922 fps
Hornady 162 AMAX - 60.0 RL22 WLR 2930 fps


These days speed only gets my attention if it starts getting too fast and then I know its time to back off. I just don't believe there is much difference between a 160 being pushed say at 2750 or 3050. Its going to do its job if we do our job.

Randy

I won't comment on the lethality and effectivenes of 160gr Partitions, because that has already been proven.
My factory 7mm Mag (Savage 110) shoots MOA at book speeds/loads (I lucked out) both in 150gr and 160gr pills with IMR4831 and RL22 respectively. ~3100 for the 150s and ~3000fps for the 160gr PTs.
160gr PTs, 64gr RL22 Rem 9 1/2 Mag primers WW brass
OAL 3.29"
150gr BTs 60.5gr IMR4831, Rem 9 1/2, WW brass
OAL 3.33"

I have not tried other primers or powder since I don't see the need.
I will vouch for 160gr Sierra Gamekings shooting very close to POI, though they can stand a bit more powder than the 160 PTs.
They kill whitetails very well too.

Tip top velocity is not everything. I've found H4831 very reliable and stable in the 7RM with every weight from 162 down. In one rifle with both 154 HSPs and 160 NPts it shrinks my groups 1/3 from the top velocity powders, and lets me use them both with the same zero. That is a more than fair trade for 50-100fps, to me.