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Campfire Ranger
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Campfire Ranger
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I think you said these were fl resized. It could be that you’re generating too much headspace or short base to shoulder length and the primers are backing out a bit and then being riveted by the case head as it backs up to the breech face. Try backing off on the charge a bit and just neck sizing the cases such that it takes a slight effort to chamber them. The cases and primers from the other mild loads fired on the same day seem to be giving a similar look so neck sizing or partial fl resizing might do it. I had this problem with my second 243 even with starting loads. Look at the primers after depriming a few cases. From the side, if they look like little mushrooms, you may have found your problem.
Velocities are a bit hi but part of that could be barrel length as someone mentioned. Several angles to consider.
NRA Life,Endowment,Patron or Benefactor since '72.
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Campfire Regular
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Campfire Regular
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I use 46 H4350 with a couple of 100 grain bullets and get around 3075 (I think) from a Kimber .257 Roberts with 22" barrel. I call that load max. in my rifle, but I suppose other rifles can handle a little more powder.
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OP
Campfire Regular
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2.5 grains over max...... I can't imagine what the problem might be. I guess that depends on which book you are looking at.
Ed
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Joined: Nov 2005
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Campfire Regular
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OP
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I think you said these were fl resized. It could be that you’re generating too much headspace or short base to shoulder length and the primers are backing out a bit and then being riveted by the case head as it backs up to the breech face. Try backing off on the charge a bit and just neck sizing the cases such that it takes a slight effort to chamber them. The cases and primers from the other mild loads fired on the same day seem to be giving a similar look so neck sizing or partial fl resizing might do it. I had this problem with my second 243 even with starting loads. Look at the primers after depriming a few cases. From the side, if they look like little mushrooms, you may have found your problem.
Velocities are a bit hi but part of that could be barrel length as someone mentioned. Several angles to consider. I FL resized because most of my 257 brass is fired from a Ruger M77UL which I neck size only with the Lee Collet die. I have some new RP and Nosler cases. I'm going to back off some and start again with new brass. Then neck size only for this Ruger No.1 and work up again. Can't hurt.
Last edited by 308ld; 09/18/20.
Ed
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Campfire Regular
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OP
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I use 46 H4350 with a couple of 100 grain bullets and get around 3075 (I think) from a Kimber .257 Roberts with 22" barrel. I call that load max. in my rifle, but I suppose other rifles can handle a little more powder. I also load for a Ruger M77UL, 20" barrel. 46.5 H4350 gets 3060fps, 47. is 3105, 47.5 is 3164. But I load coal @ 2.900 for the UL and 2.955 for the No.1, a bit longer than standard.
Ed
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Joined: Jun 2004
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Campfire 'Bwana
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Campfire 'Bwana
Joined: Jun 2004
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Look at H4350 data for 100 grain bullets in the 6mm Remington. Well over 3100 is standard fare. The 257 Roberts is the same case with a bigger hole in the end, so it's capable of even more. In top of that the OP is loading for a 26" barrel. If the accuracy is there I'd be comfortable with 3200 all day.
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Campfire Ranger
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Campfire Ranger
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Re take the after photo with the same case orientation and lighting for a better response. The shadows make the stamp look flatter, but the relative reverse of the lighting make it had to say...
-OMotS
"If memory serves fails me..." Quote: ( unnamed) "been prtty deep in the cooler todaay "
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...I can't see any sign of primer leakage like someone mentioned... I though that is what you were talking about. That isn't primer leakage but that would indicate to me a bit large fireing pin hole. Leakage would come around the edge's of the primer. No sign there but the primer fills out the pocket more than I would care for. Primer's can be a bad pressure sign in that some have softer cups that fill out the pockets easier than other's. I think he said the pockets remained tight I don't know much about checking case's for pressure from a single shot. Not surewhar the case head should measure on the cartridge your using but I'd find out and them try measuring case head. For the 257 Robert's my Hornady book says .471. If your larger than that I'd say to much pressure. Exactly.
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Campfire Outfitter
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The chrono tells you everything you need to know. Trying to read spent primers and case head expansion is twaddle.
Let's Go Brandon! FJB
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The chrono tells you everything you need to know. Trying to read spent primers and case head expansion is twaddle. Settled @ 46.5 H-4350, 100 NP. From the No.1 26" barrel. 3212, 3220, 3213, for 3215fps. Same load from my 20" .Ruger .257 Roberts gets 3075fps. Ruger N0.1....................With COVID spacing at the range.
Ed
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Campfire 'Bwana
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Campfire 'Bwana
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Were the groups like you wanted?
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Campfire Tracker
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Campfire Tracker
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Doesn't the +P load hold about 1.5 grains less powder due to the thicker webb?
"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli
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Were the groups like you wanted? Doesn't the +P load hold about 1.5 grains less powder due to the thicker webb? mm, I was at the fifty yard range with the chrono. Chrono cannot be set up on 100/200yd range. I'll work with 46.5 and COAL lenth another day at the 100/200.46.0 is not far behind at 3190fps. Tejano, from what I have seen, Nosler +P cases hold 57gr of water and the RP cases that I have are 56.5gr. So I don't see much difference.But I'm sure I could be off in my measures. Book says 55gr.
Ed
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