Flattening primers Pics added

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mnhntr

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I am shooting a .260rem and the best load I have worked up is at max according to Hodgdons data. It is Win brass, 44.5gr H4350, Federal large rifle match primers. and 142gr SMKs. I worked up this load in the heat of summer and noticed the primers have slight flattening. Should I work back down to find a lighter load? There are no other signs of pressure. Cases look normal, bolt shows no signs. I hear the Fed primers are the softest? Should I be worried? I have shot about 100 rds of this load so far.
 

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Give it a try with a different primer. If there is no flattening, drive on. If the different primer still flattens, I'd back off .5grain until the problem is solved
 
Some flattening is normal. Are the edges still rounded? A pic would help.
 
Pressure-Ejector Mark

Also looks for an ejector mark, if your rifle has a Remington type plunger. EjectorMark_01.jpg If the mark is raised a lot, you are over pressure or have soft brass. Factory ammo will produce a light mark, like on the far right.
 
I do not agree with the ‘nothing before, THEN!, suddenly and all at once the rifle was rendered scrap’. there are warning signs as in first signs, if the pressure is flattening the primer, the same pressure is having an effect on the head of the case and the primer pocket and the flash hole and on the area between the case head and and case body, and on the diameter of the case head.

Then there was the reolader that rendered a Weatherby 300 Win Mag scrap with a steady diet of reduce loads and everyone said “It ‘musta’ been a double load”,

F. Guffey
 
Your photos are showing pressure, but try a different brand before you lower the powder charger. When you change any component, start low & work up. What brand of rifle? Some Remingtons will show primer like your, even with light loads.
 
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I don't think your primers look "that" flat. Looks like the outer perimeter still has a fair amount of fillet (radius) on them. And I don't see any signs that the brass is flowing around the ejector.

However, the belly buttons (FP dents) in the primers look like they are starting to turn into "outies" to me.... Maybe switch to a CCI 200 or WLR primer.

It sounds like you've found the sweet spot for your rifle, so drop down a grain or two, switch primers and work back up....
 
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Agree with SSN Vet, they don't look bad. However, if you see any case head signs like in 243winxb's excellent pics, then definitely dial back on the charge weight. BTW, what kind of velocity are you getting with that load?

Don
 
I've never used Federal primers but I have heard a good nuber of reloaders say they are much softer than CCI or Win.. My rifle loads look about as flat as your's do, and if you aren't experiencing any other signs, stiff bolt, blown or leaking primers, or extractor transfer marks on the case head your probably OK.

GS
 
They might be a bit warm, judging by the primer flow around the FP indent.

I would try 2 things:

Different primer-the ones you're using may be on the soft side.

Different brass-Brass with larger flash holes may cause more primer flattening & cratering at acceptable pressures.
 
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