Home Forums Reloading Big Game Rifles 257 Roberts favorite powder

I haven’t had a chance to see how it does in cold weather. We don’t have really cold weather locally, so may not get an opportunity.

In our area, temp sensitivity isn’t as big an issue as in colder climates.

H100V gives me the best performance and is my go to .257R powder for the 100 TTSX.

I like H-4350 for heavier bullets like the 110 NBT.

DF

Forgot to mention temp sensitivity may vary from one round to another.

DF

southtexas,

Accuracy got noticeably worse, and POI changed about an inch. That may not seem like much, but it was a NULA that doesn't change POI much even with different bullet weights. Since velocity wasn't anything special with the max listed powder charge, I stuck with powders that didn't vary so much at different temperatures.

That said, Dirtfarmer is correct, temperature sensitivity of the same powder can vary in different cartridges, as well as with different primers. But a load dropping almost 200 fps from 70 to zero is a LOT these days, as much as I've seen with any powder.

Thank you, Gents. good info. I'll keep that in mind when working with 100V. Although, like DF, there isn't that much variation in temps where I hunt with Bobs.

Over a year ago I posted my results with Hybrid 100V in my custom 257 Roberts. It is repeated here simply to illustrate that extrapolating from one rifle/powder/bullet/primer combination to another is questionable at best. My expectations were that of the three different powder/cartridges combinations tested that Big Game would have the least variation and Hybrid 100V the most - was not sure about IMR 7828ssc powder. My expectations were based on 24 Hour Campfire posts by others.

Hybrid 100V gives me velocities 200 fps more than the often suggested load of 46 g. of H 4350 with a 100 g. bullet. My accuracy is similar for both powders and strangely the 4350 load seems to give higher pressures in my tight custom chamber.

The temperature issue intrigued me in part because of what John Barsness printed in Gun Gack about powders acting differently depending on rifle and bullet combinations (see page 28). If I recall correctly John tested Hybrid 100V in a 30-06.

So last winter it got just cold enough here for me to do a crude and simple comparison. I used Hybrid 100V in a 257 Roberts, Big Game in a 7X57, and IMR7828 ssc in a 270.

Temperature was 10-12 degrees F by my thermometer. In the spring I shot the same loads again at 80 degrees +. Ten shots per cartridge at the two different temperatures.

The 7X57 with Big Game showed an average change in velocity of 98 fps. The 257 Roberts with Hybrid 100V showed an average change in velocity of 81 fps. The 270 with IMR7828 ssc showed an average change of 68 fps.

What I learned was: A. There were too many uncontrolled variables to put much stock in my results. and 2. At the temperatures I expect to hunt in I'm not going to worry about it.

Did not test for changes in accuracy because of where I shot in the winter. CCI 200 primers were used in the 7X57 and 257 Roberts and Winchester Large Rifle in the 270 (one of the uncontrolled variables mentioned), it was also difficult to keep the temperature controlled through the whole session. For these and other reasons I have hesitated to make my results public and they are meaningful only to me.

The only way you will know if temperature will affect your rifle and load is to test it. But be forewarned, it is not as simple as it first appears! JB in another post described how he does it and he does a much better job than my simple effort.

CKW: very interesting info. thanks for sharing!

CKW,

Yes, thanks for sharing again.

As you've experienced, one of the problems of testing in actual hunting conditions is consistent conditions. As I've noted here and there (including in my recent HANDLOADER article) is that while many of today's powders are very consistent from 70 to zero degrees Fahrenheit, even the best of them vary at temperatures above 70 degrees. Which is probably at least part of the reason for some of the velocity spreads you recorded.

Don't shoot a 257 Roberts, but I gather a 6.5 x 57 will work close enough....

from 85 grain to 140 in that rifle... and the same with a 6.5 x 55...

the three powders I would commonly reach for, are what most people who know
me on the campfire, would already know my choices...

No particular order...IMR 3031...IMR 4895.... IMR 4064...

some of the velocity from your guys choices may be a 100 to 150 fps faster at most.. usually
not much fast, if at all...

and accuracy is certainly going to be right there...

and finally temp sensitivity isn't going to be that much of an issue if at all either....

Never noticed those problems in my MN days, and certainly not an issue here in Oregon...
unless I load real hot, and the temps also get REAL HOT come summer time..

The old standby powders still work just fine...and have been doing so for decades...

Thanks, MD, I had not thought through the fact that my warm temperatures were above 70 degrees. That may help explain some of the wonky results in my efforts.

Interesting topic.

Maybe there is a bigger change on the upper end, 70-100*, than 0-70*.

Would appreciate comments on that.

DF

I just shot a few 115 NBT loads over 48 gr. RL-26 with Rem 9 1/2 primers. It comes up to the case shoulder, not to the neck, which isn't bad for a magnum powder. It's pretty dense.

I was shooting groups, didn't set up the chrono. That load isn't accurate in my Brux/700 .257R. With the 115 NBT, I'm sticking with H-4350. When sighted for that bullet, my 100 NBT and 100 TTSX, H100V loads shoot a couple inches high, an inch or so to the right. So, ya gotta sight for one or the other; I'm sticking with the 115 NBT for now.

I'm gonna work up heavy bullet 7RM and maybe .300 WM loads with RL-26, don't think it fits the .257R, at least not mine. Some are pushing 115's at 3,000+ fps, I'll stick with sub inch H-4350, 115 NBT loads at 2,900+. I know first hand what it'll do.

Loonies will be Loonies...

Just can't help myself. A new load hits the Fire, gotta try it...

DF

My load for my M70 Featherweight is 46.0 gr. IMR 4350, Remington 9-1/2 primer and a 90 gr. Barnes X bullet. It's a.5 inch shooter all day with that load. The bad part is Barnes no longer makes the 90 gr. X bullet. My choice is either the 80 grain or 100 gr. bullet, neither of which my rifle likes very much. Or, I should say, doesn't like it as much as it did the 90 gr. That little rifle is a killing machine.

A 115 gr. Partition at 3133 fps is not far from what a 270 can do. I am snatching up the first container of RL26 I see.

RL26 works well with many calibers. Four or five powders will give the same velocity in the
257 Roberts. However RL26 seems to do it at lower pressure. But in the 270 with 150gr bullets the RL26 is head of the pack.
RL26 is very accurate in the 7MM mag, but several other powders make just as much velocity. Currently I
use Retumbo. If I could only have one powder it would be RL26 Or Norma MRP. In the 270 Win with 140gr Accubonds RL23
holds a slight edge. But RL26 gives you about 50fps more speed. I.m using the RL23 in my 270 Winchester for deer hunting,
RL16 in my 30/06 with 150gr Accubonds and Retumbo in my 7MM mag with 160gr Accubonds for Elk.

Dub Hornady makes a 90 gr. GMX in .257 The GMX is Hornady's mono bullet. Might give you the performance the Barnes did

See my earlier post on RL-26 with 115's in the Roberts. It may be fast, but it shot 3" groups out of my half inch gun. Burned dirty, left residue.

I'm gonna try RL-26 in my 6.5CM and 7RM. It is a dense, high performance powder with lots of potential. Not sure the Roberts is its finest application. Being dense, you can get a lot in a case without compressed loads.

DF

In my 270 Winchester with 140gr Accubonds my favorite is RL23 it has proved more accurate than RL26, but a little slower.
Pressure goes up quicker though.

I can try it in my 270 if it doesn't work out in the Roberts. I already have a can of RL22 for testing in both rounds.

Look forward to your report.

DF

I've been eyeballing that Hornady GMX. I have about 50 rounds left of the Barnes X bullets loaded. I'm being very stingy with those, but when I run out I guess I'll try that GMX.