I'm getting set up to load a Roberts. I'll be starting with 100 SGKs. If that bullet shoots well, I will probably call it good and get to shooting. I have a jug of H414 that I want to use, but the data in my Hodgdon manual only shows a difference of one grain between maximum and starting loads. Are there any characteristics of H414 particular to the Roberts that a loader should be aware of, such as temperature sensitivity?

I also noticed in my Speer manual that they suggest a magnum primer for this powder, while other companies evidently did all of their research with large rifle primers. Any thoughts on that?

Cheers,
Jeff

Couple of thoughts.

It's a ball powder so I would use a magnum primer. Magnum primers just work better with ball powder.

Yes, H414/W760 does have a reputation for being temp sensitive. So to me, you question makes a lot of sense.

I'd probably try something more modern, that give more opportunity to work up, like IMR8208.

I have no first-hand experience regarding the temperature resistance of H414, but I've found it to be a decent powder for the .257 Roberts. I can't recall if I've used it with the 100 GameKing, but I've used it with the 100 ProHunter.

Standard CCI-200 large rifle primers have worked fine. Perhaps severe cold might necessitate a need for magnum primers with this powder. Probably best to stick with the recommendations of a loading manual.

I looked at the data in the latest Hodgdon manual for the 100 Speer BTSP bullet. That one grain difference between starting load and maximum load looks odd.

Take a look at Hybrid100V. A compressed load of 48 grains shows to push a 100 grain bullet over 3,200 fps.

I never had real good luck with H414 and 100 grain bullets. OTOH, it seems to be my go-to powder for 120s.

Funny thing with those 120s ... my rifles like either magnum primers or match primers with H414 but sucked bad with std rifle primers.

Like with everything else, theory is good but it doesn't matter as much as real world results. Who knows, the next rifle may be completely different.

Tom

My go-to 257 load is a 100 grain partition and IMR-4350 powder. Not anything earth shattering for sure.....4350 has been the 257 powder for years.....

Yeppers, agree, I-4350

I use mag primers on all spherical (ball) powders, personally.

If you're looking to burn up the H414 I see no reason not to; it's got a burn rate near identical to 4350s which shine in that cartridge so it should work well.

I've always had best results from high load densities with H414, and while it is said to be pretty temp sensitive so is IMR-4350 which I've run in the Better Bob (AI) under 100s in 90 degree weather down to -10 and not experienced shift in POI out to 250 yds. Of course past performance is not indicative of future results yada yada yada.

Good luck; great cartridge!

I do have a fresh jug of 414 even though I use 4895 and 4350 for the bulk of my rifle loads. Just thought I'd give the 414 a shot rather than having it sit. I've got 100 and 120 grain Sierras. I'll load both, but it sounds like the 100s are the way to go with the Bob? I'll be using magnum primers as well, even though I see loads listed with either primer type in different manuals.

Thanks everyone.

Jeff

Let the rifle tell you which bullet weight it likes. I personally like the 117-120s. At 2800-2900, they are a sweet spot of good trajectory, low recoil, and excellent terminal performance from regular ol' CnC bullets. YMMV

Not a 257 but I used 414 w/60 gr. bullets out of a Swift for years in winter spring summer or fall w/NO issues. Dumbest thing I ever did was sell that rifle!