270 Win SGK 130gn H4831 ladder test.

mjcmichigan

Handloader
Dec 26, 2016
2,358
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1961 Winchester Model 70 Featherweight
22” barrel
Leupold VariX 3.1 2-8x
H4831 Sierra GameKing bullet #1820 130gn SPBT
Magnetospeed
56.2—2634
56.5—2692
56.8—2726
57.1—error no reading
57.4—2742
57.7—2757
58.0—2722
58.3—2795
58.6—2858
59.0—2866

Looking at H4831 which should be running quite a bit faster…I’m wondering if the powder is degrading.

Definitely expected to be over 3000fps by 59.0 grains and about 140 fps short.

I will set that can of powder aside and try a newer can.

56.8-58.0 looks like potentially a huge node.
Not sure I have ever seen a node that big.

So will repeat this ladder, same bullets, primers, but a can of powder made more recently.

The one I am setting aside is an old label… it is plastic, but not a modern H4831 label.

Also, I had no bullet strikes I could pull off the poster board. Very odd as I was using the bottom row. Clearly the gun need some love. Wondering what it was sited last. Can’t imagine how anything could miss that poster board at 100. But it did. Will load up some for the 25 to find where they are before next ladder.
 
Well, tried a new jug of H4831sc, and basically got the same velocity. The old jug of powder is fine. Using the Barnes TTSX 130 and RL17, I’m getting 210fps more than I’m getting from H4831.
Interestingly, comparing manuals. Hornady Recipes vs Sierra Recipes…Sierra stops at 58.6, but Hornadys goes to 60.5 gn. The Sierra recipe at 58.6 is showing 2800 as Thier estimated V.

I have the gun in paper at 25 yards. As a bit over 5’ high at 100 yards… wonder what he was zeroing at? Almost looks like 500 y.
 
Well, tried a new jug of H4831sc, and basically got the same velocity. The old jug of powder is fine. Using the Barnes TTSX 130 and RL17, I’m getting 210fps more than I’m getting from H4831.
Interestingly, comparing manuals. Hornady Recipes vs Sierra Recipes…Sierra stops at 58.6, but Hornadys goes to 60.5 gn. The Sierra recipe at 58.6 is showing 2800 as Thier estimated V.

I have the gun in paper at 25 yards. As a bit over 5’ high at 100 yards… wonder what he was zeroing at? Almost looks like 500 y.
The H4831 SC is a slow powder, I had the same issue with my 6.5 x 284 pushing the 143 -147 ELD's pretty slow. I ran 3 round charges up to book max and was still about 100 fps below book speed, so I went about 3-4 grains over to get to 2890 fps and it the accuracy node was at that spot. It's still shooting in the .2's @ 100 with the 143 ELD-X. I was watching pressure carefully and it did work for me. H4831SC is very temp stable.
Did you have pressure like hard bolt lift or flattened primers? If not, I would go higher on the powder charge to gain more speed, as long as there is no pressure.
 
H4831 been a standby for years just not the fastest kid on the block compared to newer powders. You can lean on it some though. Dan.
 
I've never been able to make H4831 sing in my Kimber either. Only got mediocre accuracy, and couldn't break 2900 fps. H4350 and RL19 both gave sub half MOA accuracy at 3050-3060 fps. They would both break 3100 fps as well, without getting squirrelly but accuracy suffered.
 
The H4831 SC is a slow powder, I had the same issue with my 6.5 x 284 pushing the 143 -147 ELD's pretty slow. I ran 3 round charges up to book max and was still about 100 fps below book speed, so I went about 3-4 grains over to get to 2890 fps and it the accuracy node was at that spot. It's still shooting in the .2's @ 100 with the 143 ELD-X. I was watching pressure carefully and it did work for me. H4831SC is very temp stable.
Did you have pressure like hard bolt lift or flattened primers? If not, I would go higher on the powder charge to gain more speed, as long as there is no pressure.
No signs of pressure at 59 grains… will push it a little harder.. I would like to get it up to speed. Case volume was pretty tight..so not sure I can get far.. but will work up in 0.3gns..
 
Bought two pounds of RL17 today at Joe Gunn Sanford MI. He has a smattering of powders. rl7,10,15, 19,22,23,25. Took the last two 17’s, and didn’t see any 26.
Sounds like a great snag on your part. I haven’t seen RL17 in quite some time.
 
My experience with 130 gr. bullets in a 270, the powder sweet spot for performance are powders are: H4350, RL-17, RL-19.
My 270 has a 24" barrel and all three of these powders deliver accuracy in my rifle and with higher velocity than H4831 generates.
If you're not getting the accuracy you are hoping for, try a flat base bullet and see if that has an impact. I have a 257 Bob that shoots splendidly with flat base bullets, but falls apart when shooting bullets with boat tails.
 

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