I went out today on a windy day to try out some 140 gr. Partition loads for my 7mm STW. I worked up five batches in 1 grain increments form 74 to 78 grains. I checked each shot with a chrono. Each grain increased the velocity by about 50 fps. and seemed to shrink the group. I ended up with the last load at 78 grains averaging 3,301 fps. with a four shot group of .721".

So now I am half a grain above the max load listed in the Nosler manual and 2 grains below the max load listed in the Hodgdon manual. I see no pressure signs so far and the laods track the velocity in the manuals. 3,300 fps is plenty of velocity, but I am intrigued by the fact that the groups seemed to be tightening up, so do I keep adding another couple of grains to see where the groups go? Or do I play with some of the other variables? The cases were virgin, so I am curious to see the effect that once fired brass will have. The bullets were set .010" from the lands, so I don't know if there is much to play with there.

I had not heard good things about the accuracy of Partitions, but I was pleasantly surprised at how well they did. 3,300 fps and a tough bullet ought to be an efficient game load.

Thanks,
Rick

What powder are you using and what is the length of your barrel--I have quickload and may be able to make things a "little less" fuzzy. d kraky

I am guessing you are using imr7828 powder.If this is correct I would try 79 gr and check for pressure.If there were still no pressure signs I would try 80 gr.This should provide about 3400 fps which is still not pushing things in a 7mmstw.My own rifles produce 3450 fps and 3500 fps using 78 gr and 80 gr of imr 7828 with no pressure signs.

[This message has been edited by stubblejumper (edited 03-25-2002).]

Depends on the powder you are using...but basically, if you are showing no signs of pressure, start working up 0.3 grains at a time...until either pressure signs appear, or performance starts to fall off...

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Sorry I didn't mention the powder, but it is IMR7828 out of a 24" barrel. I guess it makes sense to work in smaller increments as I approach the max loads, it just seems like by the time I get loads worked out for three or four bullets I may be close to burning out the barrel ;-)

Thanks,
Rick

From what I see studying differnt sources about 80 grains is very close to max. But the fact that you are at 3300 fps with a 24" barrel with 78.0 would make me think you may not make it to 80.0 without pressure signs.
I think Riciardelli has hit it on the head.
Work up in small increments from 78.0. You won't hurt your barrel if you let it cool between shots. Also--THERE IS NOTHING WRONG WITH ACCURACY AND 3300 FPS!!! PS-- if you keep the headspacing real close to chamber dimensions when you resize that virgin brass you may be able to push it just a little more with good brass life. Good luck d kraky

Well I might be seen as being too safe , I allways work my way up to max & past max in .2 grain increments, & always seem to find a accurate load in those small increments

Good luck & Fry those Partitions down range

Thanks for the suggestions. I think that I will try building up in smaller increments up to 79 grains, and that should give me an idea about whether the groups are still shrinking or begin to open up. I thought I would make another batch at 78 grains with once fired brass as a control sample so I can have something to compare to the new loads. The only varaible that I can't seem to control is the wind, it is always windy in Dallas and it is hard to factor that into the groups.

Thanks for your help,
Rick