So I’ve been working on some 220 grain smk loads for my win mag. My goal was a good grouping load around 2800-2850 FPS.

Decided to use my h1000 that I have 4 pounds of. I think it’s 5-6 years old.

Norma brass.

So I started my work up in the middle of my load data, knowing I would end up over book.

I kept working up, keeping an eye on pressure signs. Found my load at 77.5 grains. 2,850 FPS with great groups. Well over book.

After, I started looking on the net a bit at other people’s loads. It seems that I’m WAY over what other people run. Some guys are getting that FPS at 74.9 grains.

I’m wondering if this could be a case of powder degradation? I know there are a lot of inputs that could cause this, but 2.6 grains with the other major parts being the same seems like a lot of difference, even in a big case.

Or is this just maybe due to a looser chamber, ext, ext?

Yea sorry.



I’m about 20 thou off the lands. Pretty close to what other data I’m seeing in other people’s loads as far as OAL.

My Hawkeye seems to have a pretty common chamber size. No crazy long throat or anything.

Maybe I’m just thinking in smaller terms? That’s a huuuuuge difference in 5.56. Maybe not for Winmag.

Case volume may also play a part in this.

It can be many things, differences from lot to lot on the powder, differences in the barrel=========, even when from the same maker...difference in primers, case volume, even seating cal can all affect pressures, the only thing that matters in the end is you are not seeing high pressure signs even on those super hot/cold days..

This may well be the culprit.