Hello fellow reloaders. I have a FPS question. At this time, i do not own a chronograph, neither do i have a place to borrow one.

Anywas, in my 7mm mag, i am shooting 60gr. of H4831 behind a sierra 175 SBT with Rem 9.5 primers, with know sign of pressure. In my sierra manual, it reads that im getting just about 2700FPS. Does anybody know for sure with this load where i would be in FPS? I would like to begin to work up but i would feal a little more comfortable knowing the FPS. I realize all guns are differant, but what do u guys find the max to be with H4831 and 175gr. bullets?

Any help will be gratly appreciated. Thanx

H-4831 From 53.7 grains to 70.0 grains
CCI-200 Primer

In my old Hodgdon #19 manual they show 63 gr of 4831 as max with the 175 Hornady at 2869 fps. But I have not tested this load.

I think that Riciardelli's 70 gr posted above is not in context and is not a load for a 175 gr bullet. Don't use it.

Your estimate of 2700 fps is a good one.

The maximum, commonsense working load in your rifle is a unique thing and you must decide what it is yourself.

The only way to know velocity is to use a chronograph.There is no way to accurately estimate velocity.Even guns with the same barrel lengths can produce velocities that vary by over 100fps with the same load.

Redneck:

The velocity does not matter much, but the trajectory does! Load up some ammo, go out and check your zero @ 100 yds, (say +2") then shoot some groups @ 300 yds. This will tell you all you need to know. Then check your drop against the tables and get a fairly good idea of your velocity and your point of impact at other ranges.

JimF

Velocities can be estimated. In this case 2700 is a good estimate. All you have to do is interpolate the suggested and max loads. Others have said that the data they read does not correspond with their chrono's. So be it. Mine does.

And the temperature and bbl length are rarely given. In this case 2700 was taken as a round number and it's close enough.

Redneck, my 7mm Rem mag really shoots well with that long Sierra 175 you're using. I'm using 64 grains of H4831, just under the max load of 64.5 in the Sierra manual. I have however substituted the Federal 215 primer instead of the Remington primer.

No excess pressure signs on the cases even in hot weather. Had a plenty warm rifle with 20 round strings of slow fire. I have no plans to go above Sierra's recommended max load.

It would seem that your current load is well within safe specs. When I was working mine up, I started at 60 grains. Loaded 5 each at 60, 61, 62, etc until I got to 64 grains. Everything works well, accuracy is excellent and I've got a good long-range load.

I've also had good results with RL-22 powder and H870 in the 7mm Rem mag. Regards, and use internet loading data with caution. This load worked in my rifle, and is under Sierra's max, but you should work up your own.

Regards, Guy

Redneck, Forgot to mention velocity. 2930 fps with a 26" Rem Sendero, 64 grains of H4831 and some really nice groups. Regards, Guy

Redneck, your 60 grain load is probably very close to 2700 FPS, or perhaps a bit less. In effect, you are getting 7X57mm Mauser ballistics from your 7mm Magnum, a very mild load. In my Ruger No. 1 with a 26" barrel, I use 68 grains of H4831 or Norma MRP, with the 175 grain Nosler Partition bullet for 3050 FPS. I have used as much as 69 grains of Norma MRP, but now shoot a reduced load. I DO NOT recommend this load to anyone, unless they approach it slowly from at least 10% below!!

Lapua factory 170gr's go 2600fps in my 22" M70 7x57

R-West, I was first able to get velocities of over 2700 FPS with 175-grain loads in the early 1970's, by using a load of Norma N205 taken from Speer Reloading Manual No. 8. When Norma discontinued N205, they replaced it with MRP, which also proved capable of producing similar velocities with 175-grain bullets. I recently discovered that RE22 (in a highly compressed load) will do the same thing as N205/MRP with absolutely no signs of abnormal pressures in either my Ruger No. 1A, which has a long throat, or an FN M1924 Venezuelan Mauser, which does not have a long throat. As a matter of fact, I have concluded that it is NOT POSSIBLE to get enough RE22 into a 7X57 case to give excessive pressures with 175-grain bullets in a MODERN, STRONG ACTION!! I WOULD NOT use any of these loads in an action designed prior to the Model 98 Mauser!!

My apologies Larry, I would never have thought it possible to get that out of a 7x57 with 175's.

In all the time I played with various 7x57's, I never tried N205 (don't even know if I ever saw any of that around here) or MRP/R22 in any of them. Always used the O'Connor loads of 43 - 45 IMR 4320 and 140 grainers and however much H4831 I could get into the case with 160's. According to him (didn't have a chrono back then) should have gotten around 2900 with the 140's and 2600 with 160's. Actually, am getting the itch for another 7x57 (one of those CZ550's with full stock, maybe?), and I'll try some R22 loads.

R-WEST

R-West, I believe that H4831 could also produce velocities like we are discussing with the 7X57 also, EXCEPT you can't get enough of it into a 7X57 case! MRP and RE22 have pressure/velocity characteristics similar to H4831 when used in the 7X57mm case, BUT, they are much denser powders with smaller grains than H4831, thus YOU CAN get enough of either of these two into the 7X57mm case to give the velocities we are talking about with 175 grain bullets. (I think perhaps the magnum-type WW ball powders would have been capable of such performance also, but they were all discontinued before I had a chance to test them in 7X57mm.) Kinda makes the 7X57 into a different sort of proposition, doesn't it?

R-West, where is Windber? I live near Hagerstown MD just off I 81, 1.5 miles into PA.