Home Forums Hunting & Shooting Ask The Gunwriters 7mm Rem Mag and Hodgdon's data

I have always loaded from my old Hodgdon reloading manual and happened to look at their online reloading data. I discovered that my old load for my Rem Model 700 BDL 7mm Rem mag is way over their recommended maximum load as listed in Hodgdon's online data . I compared my old Hodgdon book with the current online data and found huge discrepancies in the listed volumes for H 4831. My old 7 MM with 160 gain Sierra Spitzer, 65 grains H4831 Federal 215 primer exceeds the60 grain maximum. What's happened?
I'm confused. I have used my old load safely in several 7mm Rem Mag rifles for the last 20 years.

It means they now have corporate lawyers. If you want another reference, the older Hornady manual from the 1970's is even hotter. If my memory is correct they had 72 grains of H4831 for a 139 Hornady SP.

Books are only guides. Your rifle will tell you the max load, not some lawyer reviewed paper.

Many of us don't believe lawyers have much to do with a general trend toward lower powder charges in published data. I strongly suggest looking at the writings by John Barsness including Gun Gack and generally using a chronometer to compare loads in the field with book loads and so much more.

I do believe that changes in pressure measurements are the main reason for lower charges.

As more different lots of powder have been tested and with changes in sourcing sometimes the labs have just tested a faster lot of powder than they did before.

I am by no means saying this has happened in any particular case. I am saying H4831 has not been exactly the same powder of the years. There has been some talk that H4831 has varied enough to make some of Jack O'Connor's earlier published loads for his pet .270 less desirable with later lots of H4831 from different sources. Things have definitely changed over the years. Since I have no control and little knowledge of possible changes I mostly go with the latest editions of data books and fresh powder within the limits of my pocketbook.

In the special case of the 7mm Remington Magnum ballistics from this very board an earlier thread titled Re: Pressure excusions/spikes ? for MD & others

Further much of the faith in pressure signs is misguided and many loads in the field are simply over pressure without warning signs. See extensive discussion about changing velocities and pressures with the 7mm STW and dropping charges and velocities with more testing after the introduction.

And most important, a series of over pressure loads will eventually lead to a rifle that will fail at previously safe pressure loads.

Not something I'd worry about.

In 40 years of loading the cartridge all over the map and maybe 20+ rifles, I've never had an incident of any kind.

Despite the issues with pressure swings I notice the Nosler Manual loads deliver excellent velocities. I'd expect they are to SAMMI spec.

Whether folks worry about it or not, and safe practices will keep most people out of trouble most of the time it's still true that old data has issues

Frex this from the O'Connor Center in Lewiston Emphasis added. H4831 has changed several times and few people use O'Connor's 62 grain load with today's powder and bullets and cases and primers. It's not just the powder that has changed over time.

Thanks for the advice.

Have you had any problems loading the 7 Rem Mag? Blown primers/cases etc.?

The stuff from the JOC center is interesting but pretty basic.

Again I would not worry about it.

As to pretty basic I go along with Bruce Lee - advanced is just basic done right. I very seldom worry about what other people shoot in their own firearms on their own property. I do sometimes take an interest where I am a range safety officer. I will say folks wouldn't use Jack O'Connor's load of H4831 in a .270 and it's not obvious that using H4831 loads of the same vintage in a 7mm Remington Magnum is any wiser. As with the .270 I'd be more inclined to try IMR7828 to match old H4831 performance in a 7mm Remington Magnum.

I don't blame on lawyers what I think is associated with the change from copper units of pressure.

My own experience of drastic overloads is pretty much limited to handguns.

The most I can say about the 7mm Remington Mag is that I was foolish enough to swap a really nice .270 for a 7mm Remington Magnum thinking it was a significant step up in performance.

It wasn't.

I found the 7mm Remington Magnum and the .243 Winchester to live up to their reputations for erratic internal ballistic performance (not so much erratic on game which it wasn't but the 7mm, despite Les Bowman's praise and Warren Page's do everything Mashburn, was no better if no worse than anything else even close) .

I replaced the .243 with a 6mm Remington and did not directly replace the 7mm figuring I either wanted more or would settle for less.

Bob

I know that nothing is the SAME as it was 40-60 yrs ago.
Yes, we need common sense.
There is 1fact that's constant - brass is the weakest link.

IMO as we 'APROACH' dangerous pressure, THE brass will indicate it---
so we GO the other way.

I went for several yrs w/o a chrono but since having one since 1981---
as MD says compare velocities with PRESSURE tested loads.
GET a chronograph ! ! !

Some of US have components from 40yrs ago. I have @10 lbs of Surplus 4831. I've saved it for my 284 W and JOC's pet.

There are newer & in some cases (pun not intended) better powders available but this is a KNOWN quantity.

Jerry

Here is a page from the 44th Lyman Manual.(1967)It's a bit different than todays loadings.I don't load my 7mags quite as hot as these loads,but my loads are closer to these than most of the modern published data.Todays loads are just a belted 280.The pressures are kept below 60,000psi.

Gee....my experience has been that the 7 Rem Mag and the Mashburn run circles around the 270(which is a sentimental favorite but facts are what they are).

I got all three right here...plus maybe another 8-10 rifles in the hands of friends chambered for them all.We won't count the others I've owned over the last 40 years.

The biggest problem I have seen with the 7 Rem Mag is that velocity varies so much rifle to rifle due to things like throats and barrels and who's loading what on what day, that you run into all kinds of disagreements on velocity.

Again take a look at the Nosler Manual to get a more realistic assessment of what the cartridge will do..

I am constantly amazed at how the cartridge gets such a bad rap; yet no one ever says that the 264 has any issues. But Ive found it far touchier to load to potential than the 7 Rem Mag.

One of the top ten BG cartridges in the world yet it befuddles a lot of people.

I agree on the 243...


Here's group from another one of those quirky, dangerous 7 Rem Mags...Velocity about 3125 as I recall.I could shoot the barrel out with that load without and incident.

You want to see some really flat primers, try Elmer's pet 2400 load in the .44 mag with today's 2400.

I load my 7mm RM with H1000 and the 150 Nosler Ballistic Tip. I have been using this combination for 25 years and have been keeping records from every batch of 50. I have been getting a MV of 3145 with an extream spread of 86 fps. This has been pretty consistent whether during 90* summer or 15* winter. Every thing I have read about the 7RM says the problems don't occur until the 175 gn and up bullets come into play and usually only then with eroded throats.

Bob,

Is that from a rifle with a SAAMI spec throat? I thought you have or had several 7RM's w/ a slightly modified throat.

David

I heard the part about eroded throats.

I'll have POPCORN when I get back.

Good luck Bob

Jerry


ps, I have many things to say from my experience but I don't have time today. Suffice it to say, I agree with you.

David yes it is a SAMMI spec throat. I used to set them up longer to seat bullets out but stopped doing it at some point.

Here is the rifle.

I was just looking at some QL data on another site, involving the 162 and 175 gr bullets with newer powders like MagPro, Retumbo, etc.

The velocities were the same/same I've been seeing from the cartridge for years with the 160-ish gr bullets at a bit over 3000 fps,and 175's maxing at a bit over 2900 fps.These were all at pressures of what QL says is around 59,000 psi.

By the time you bumped past those velocities QL was screaming for you to stop as you got over 60,000 psi.

I understand QL is a "model" ut it's still interesting how close it is to what I have seen from quite a few rifles of my own over the years. I always used to say when you see 3050 with a 160 from a 24" barrel, you've arrived.

No wonder I have not had a lot of problems with the cartridge all these years....

Robt,

One big difference in the data from your old Hodgdon manual and today's data is H4831. I don't know which manual you have, but my No. 25 and 26 manuals shows exactly the same maximum load, 66.0 grains with "154-162' grain bullets. This lumping together of bullet weights was common back then, mostly because almost all bullets were cup-and-cores, so produced similar pressures.

It was also common to reproduce exactly the same data in succeeding versions of the same manual, which saved time and money. But there have been three basic versions of H4831 over the decades. First was the original military-surplus powder designed for 20mm cannon rounds, which just happened to be perfect for the .270 and many other cartridges.

The mil-surp powder ran out in the mid-1970's, so Hodgdon started having a similar powder made in Scotland, also called H4831. This version was reportedly a little "hotter" (faster-burning) than the original mil-surp stuff. I don't really know if it was hotter, since I had enough original H4831 to see me through until the next--and present-- "Extreme" version of H4831 started being made in Australia.

I do know that my remaining sample of the mil-surp H4831 (a can I opened last year) is considerably "hotter" than my present batch of Australian Extreme powder. I shot some of both in my present .270, using 130-grain Hornady Spire Points, Winchester cases and Winchester Large Rifle primers, all from the same lots, and 61.0 grains of mil-surp powder resulted in almost 100 fps more velocity than 61.0 grains of Extreme H4831.

All of this is only to demonstrate how much H4831 has varied over the years. It still varies somewhat from lot to lot, like all powders. But the other thing that's changed is bullets. As mentioned, they used to almost all be cup-and-cores, but many other bullet-types started appearing in the 1980's, and today there are far more. Each can produce very different pressures with the same charge of powder.

As somebody else has already mentioned, during this period the method of measuring pressures changed from copper-crusher to electronic systems. Some even older manuals worked up data the same way handloaders do, by looking for pressures signs. (Speer "worked up" data for many years, even though they had copper-crusher testing equipment, apparently because nobody at the Speer plant knew how to run it consistently.) Today's electronic equipment indicates that ammo worked up by handloaders often produced pressures in the 70,000 PSI range, or even higher. Whether this is dangerous or not is another question, since much depends on conditions of both the rifle and weather when the ammo's fired.

At any rate, powder and bullet companies eventually realized, partly due to actually blowing up a few test rifles, that lumping various bullets into one category didn't work.

This is one reason why the exact same data 7mm Remington Magnum that ran in several older Hodgdon manuals was eventually updated. The 27th Hodgdon manual, published in 1998, does not lump 154-162 grain bullets together. Instead it lists separate data, though still in CUP (copper units of pressure), for the 160 Nosler Partition and 162 Hornady SPBT. The maximum load for the Partition is only 60.0 grains, but for the 162 Hornady it's 64.0 grains. However, both maximum loads produced exactly the same amount of pressure in the test barrel, 49,800 CUP.

These days some of Hodgdon's on-line data still lists older CUP loads, but like all of the industry their data is being switched over to PSI readings from electronic equipment, though first for newer powders and bullets. This is why the on-line data for 160 and 162 7mm Remington Magnum loads is exactly the same CUP loads listed in the 27th manual.

No doubt the Sierra bullet you're using produces pressures much closer to the 162 Hornady than the 160 Nosler Partition. So the 162-grain data is probably much closer to what's actually happening with your load--which is then only one grain over the maximum charge listed.

Along with something like five iterations of 4831 the pressure specs for the 7RM and 243 were reduced at some point when they were both loaded with 7828 Data powder the bulk form of what we have now. Both had pressure excursions and wide variations due to the different chamber specs and throat erosion.

Different methods of pressure testing and different barrels will produce wide variations in pressure. As the old copper crusher receivers were phased out the electronic psi barrels gave different and probably more accurate results.

On a long throated almost free bored 7RM I just split the difference between the 7RM and 7 Weatherby. I use only powders slower than R22 so it is difficult to put too much powder in the case. Max loads that fill the case with light compression only work best for me and an overcharge will spill out of the case.