Murphy, question on 7mm rem mag loads

[Kurt S]

Murphy,

Back in the mid 70's when I bought my Ruger 7mm, I worked up a load for it that served me well for many yrs. I don't know where I ran across the data, some reloading book that I can't find in all my junk. Anyway the data called for a max of 64 grns of H4831 with a 175 gr jsp and a mag primer. I worked up from somewhere around 60 grns to the max of 64 and found the later to be the best. I would load up 20 and it would last 2-3 yrs depending on how much hunting I did. I never saw any glowing signs of over pressure, but would pitch the brass after 4-5 reloads.
Lately, I can't find any loading data that calls for much more than 58-59 grains max.

What changed?

Kurt

[Bill S.]

I know, I'm not Murphy but I do reload for the 7mm Rem Mag. I've done about the same you have, although I use IMR 4831 with a 154 grain bullet. Depending on the manual I look at, I may or may not be exceeding the max load. Reloading manuals have become more conservative over the years because of liability problems and also the older rifles out there that can't take the pressure. Usually you find that in calibers that were popular in the early 20th century. If the load shoots well with no signs of over pressure on the brass, then you should be ok. You can always take your rifle to a gunsmith and have it checked to insure everything is ok.

[BrownBear]

I'm not Murphy, but I have a lot of experience with both 4831 and the 7mm Rem Mag in an assortment of rifles.

Not only are manuals more conservative today, there are lots of versions and variations of 4831. There's the original military surplus version once sold by Hogdon, the IMR version, and I think at least two more recent releases by Hogdon since their stocks of original surplus ran out. Each of these is different in burning rate, and there can be variations between lot numbers. I'd even bet you might find changes in specs for the brass you buy today compared to the stuff you originally loaded.

I've still got a little over 30 pounds of the original surplus 4831, but in anticipation of the day it runs out I've tested each of the new ones to come along. So far mine is the slowest burning and allows the largest charges, but it doesn't necessarily always give the highest velocities at max.

Bob Hagel in his book "Game Loads and Practical Ballistics for the American Hunter" (1978, Random House) published the most aggressive loads I know of for the original 4831. He recommended 66 gr for 175's, 69 gr for 160's, 70 gr for 150's, and 71 gr for 140's- all in Win cases with CCI 250 primers. In all the 7 Rem mags I have owned velocities stood up to his claims, but my overall reaction is not in my rifles and not with my brass.

Those are very hot loads and brass life is two or three firings. The book is a good read on many points, but his loads in all calibers are unbelievably aggressive. Pressures are quite high even with the original surplus 4831, and I bet the loads are absolute bombs with any of the other versions.

I approach each new version and each new lot of 4831 as a new powder, and carefully test loads with it before deciding on max. When I find one I really like I go ahead and buy 5 or 10 pounds, because sure as the sun rises there's going to be another version coming around the corner with yet another set of performance characteristics. I heartily urge you to use the same precautions.

[Murphy]

Kurt,

I have a post on this powder under Burnin' Powder but will elaborate a bit more here.

I believe the 7mm Remington Mag was conceived with the original 4831 powder. The IMR series of powders as I recall came out in about 1972 when DuPont got into the powder making game. Some older loading manuals from the 1960's just list 4831 powder with no prefix, this is the original Hodgdon surplus 4831. This original powder was the slowest of all under the 4831 label, new or old. Your H4831 load of 64.0 with the 175 grain is about max but not escessive. It would not work with the newer H4831sc-Extreme powder, but a good load could be developed with the new powder. It is hard to fill the 7mm case and the best loads I have had were not full but slightly under. I have obtained over 3000 fps from the 160 grains and that is hummin'. My go to load for a long time was 64.0 grains of IMR 4831 but with more recent lots I have settled on a max load of 63.0 grains of IMR 4831 which is 3020 fps from a 24" gun. Another good load for the 160 grain is 63.0 grains of RL-22 for about 3050 fps. With the 175 grain I would reduce to 60.0 to start. I think the Nosler Manual No. 5 lists IMR 4831 with 175 grain bullets and 60.0 grains as max at about 2850. Im sure H4831sc=Ex. will be fine as a replacement.

I like the 7mm Remington. I have hunted with it quite a bit and shot it over range a lot. It has the killing power of the 30-06 and the trajectory of the 270 Win. A good mix at that. It makes hitting a long range easy and with it's mild recoil and long range punch it's a real dandy. Many good bullets and powders make loading a breeze also.

The two previous not Murphy's hit the nail on the head, not much I could add. Just that powders come and go, we have to adjust to the times.

One more thing I'd say.........you need to shoot more. One box lasts for years.........I don't know what to make of that! Good shootin'.

Murphy

[Kurt S]

Bill, Brownbear, Murphy,

Thank you all for chiming in, all great info! And the Burnin Powder post, great.
I used to hand load allot, pistol and rifle both. Life got busy raising the kids, building a house and all of life’s time consumers. I found that old load so reliable that I didn't question it, just went hunting and with an exception or two, used one round. With a couple rounds fired just to make sure things were good to go, a box could last a couple yrs. mostly a caribou or a moose per year was the norm but one year it was a moose, a caribou, a bear and a sheep...the grand slam so to speak.

What inspired the question was I finally ran low on the original 4831. That last can still has the price on it; $1.95 for the pound can so you can see it's been on the shelf awhile.
As you all have pointed out, it's prudent to look at this as a new ball game and not assume it's all the same. I looked at the data tables and was surprised to see the reduction in max loads and went further into it. I’m very cautious when it comes to reloading and figured there had to be more to this.
I did find my old book, a Sierra manual that listed a max of 64.5. Looking at my reloading log, I found that I had gone from 60 grains up to the max listed and back down to the 64. Very accurate, consistent and as you point out Murphy, the gun loved it, i.e. its sweet spot.

There is a notation in the Sierra manual in the 7mm Rm section and I quote;

“In august of 1970, PO2 Thomas Treinen a shooter on the navy rifle team used this cartridge with the Sierra 168 gr. Matchking bullet to win the 1000 yard Wimbledon match and set a new record score at Camp Perry, Ohio. His load was a 66 1/2 gr. of 4831 and the Remington 9 1/2 Magnum primer with a velocity of 3050 feet per second.”

It was a great powder!

Recently, I tried the H4831 (long grain) and although not bad at 58 grains, not what I had in the past so your input is much appreciated as where to head from here. I will try the H4831 sc and IMR 4350 and see where that leads.

Thanks much

Kurt