February 26, 2001, 09:56 AM | #1 |
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Join Date: August 31, 2000
Posts: 179
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I'm been trying to develope a good accurate load for my Ruger 7mm RM. I choose to use the Hornady 139gr. SST bullets and H-4831 Powder. I started at 64gr increased the amount of powder in 1/2 gr. increments untill I hit a max of 67 gr. I loaded 4 rounds for each amount and started shooting the rounds. I noticed that the groups were really bad, around (1.5-2") until I shot the 66.5 gr. loads and got a 5/8" group. Is it pretty normal to go from 2" groups to 5/8" groups just but changing powder levels? When I shot the 67gr. loads then groups were back around 1.5". Where should I go from here? Should I start playing with seating depths?
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February 26, 2001, 04:26 PM | #2 |
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Join Date: November 22, 1999
Location: Green Country, OK
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If it were me, and I wanted to make a change, I would back off being near max, make the change and start over.
As far as what's normal, only you can tell from the performance of YOUR rifle. That's why it's so much fun. You get to shoot [ALOT]. sundog
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February 26, 2001, 09:52 PM | #3 |
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Join Date: January 17, 1999
Location: Waco,TX
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7mmRM
Nosler 162gr BT, 64gr H-4813 - NOT IMR 4831!!!
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February 26, 2001, 11:26 PM | #4 |
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Join Date: April 4, 1999
Location: New Mexico
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Unless you are determined to use the 139 gr bullet, try some different bullets. I haven't checked the max loads, but if 67 gr is the max load for your gun there isn't going to be much velocity difference with 66.5 gr. If that is the most accurate why not use that? I haven't personally found a 1/2 gr powder difference to make that much difference, but it evidently does in your gun. If I got 5/8" groups at 1/2 gr below max I wouldn't try anything else. If you just want to play try different seating depths. Sometimes different powders make a difference. Jerry
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April 13, 2001, 04:19 PM | #5 |
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Join Date: April 20, 2000
Location: USA
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I'm surprised that nobody has mentioned the obvious and that is, don't draw any conclusions from only one group. You should shoot 5 to 10 groups with a particular load before settling on it. For instance, while working up loads for my .300 Weatherby, I shot a group that measured just slightly over .1" (that's point one, not one). I didn't make that my preferred load, however, because after further testing it just didn't pan out. That outstanding group was simply an anomoly. If you get a good initial group with a particular load, by all means record it, but do further testing with it before drawing any conclusions. Dan
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