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Rifles, Reloading, Optics, Equipment
Reloading
Primer Cratering Question
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<blockquote data-quote="Fiftydriver" data-source="post: 209559" data-attributes="member: 10"><p>It is more common in Win M70s and Savage rifles but bolts with a large diameter firing pin can also result in primer cratering even if the firing pin is a good fit to the firing pin hole in the bolt.</p><p> </p><p>A modern firing pin should be roughly 62 thou in diameter and no more, unfortunately most are larger then this and many are MUCH larger then this, some in the 80 to 85 thou range, simply far to large to prevent primer cratering with modern high pressure chamberings.</p><p> </p><p>Is it really a problem, depends on how bad the cratering is. If its severe enough, you will get pierced primers. I would say from the velocities you are getting, the cratering is not caused by excessive pressure, I would say moreso from a problem with the firing pin and hole dimensions.</p><p> </p><p>If your not seeing any shiny spot on the case head your fine with pressure. Remington factory loads will show a faint ejector ring on the fired case, very faint but you can see it with most of their factory loads, if you load your ammo to match that same faint ejector ring mark you will be very similiar in pressure.</p><p> </p><p>ALso, if your bolt life is easy and your primer pockets are lasting you at least 4 firings your fine with pressure, more is better but 4 firings per case with a modern magnum is acceptable. </p><p> </p><p>Simply put, in most cases its more of an eye sore then anything else but if its to the point that your getting the occasional pierced primer, something should be done to correct it.</p><p> </p><p>Also remember that your shooting Solid bullets which are very hard compared to a lead core bullet and also I believe the E-tip is longer then say a 180 gr Accubond. If I remember correctly, they are nearly the same length as the 200 gr Accubond so they will have more baring surface then the conventional designed bullets which will limit your velocity a bit compared to a lead core bullet.</p><p> </p><p>I would say your top end loads in the 3265 fps range may well be near the top end of what you will get with these bullets. The 180 gr Accubonds can usually be driven to well over 3300 fps but remember again, they have less baring surface and they are also a softer bullet which will conform to the bore dimensions with much less engraving pressure then a solid bullet design will.</p><p> </p><p>Again, I would not say cratered primers is a high pressure indicator, when seen with other pressure signs, certainly it is but if its by itself, generally its a firing pin and hole dimension issue and unless it really bothers you, can just be left alone.</p></blockquote><p></p>
[QUOTE="Fiftydriver, post: 209559, member: 10"] It is more common in Win M70s and Savage rifles but bolts with a large diameter firing pin can also result in primer cratering even if the firing pin is a good fit to the firing pin hole in the bolt. A modern firing pin should be roughly 62 thou in diameter and no more, unfortunately most are larger then this and many are MUCH larger then this, some in the 80 to 85 thou range, simply far to large to prevent primer cratering with modern high pressure chamberings. Is it really a problem, depends on how bad the cratering is. If its severe enough, you will get pierced primers. I would say from the velocities you are getting, the cratering is not caused by excessive pressure, I would say moreso from a problem with the firing pin and hole dimensions. If your not seeing any shiny spot on the case head your fine with pressure. Remington factory loads will show a faint ejector ring on the fired case, very faint but you can see it with most of their factory loads, if you load your ammo to match that same faint ejector ring mark you will be very similiar in pressure. ALso, if your bolt life is easy and your primer pockets are lasting you at least 4 firings your fine with pressure, more is better but 4 firings per case with a modern magnum is acceptable. Simply put, in most cases its more of an eye sore then anything else but if its to the point that your getting the occasional pierced primer, something should be done to correct it. Also remember that your shooting Solid bullets which are very hard compared to a lead core bullet and also I believe the E-tip is longer then say a 180 gr Accubond. If I remember correctly, they are nearly the same length as the 200 gr Accubond so they will have more baring surface then the conventional designed bullets which will limit your velocity a bit compared to a lead core bullet. I would say your top end loads in the 3265 fps range may well be near the top end of what you will get with these bullets. The 180 gr Accubonds can usually be driven to well over 3300 fps but remember again, they have less baring surface and they are also a softer bullet which will conform to the bore dimensions with much less engraving pressure then a solid bullet design will. Again, I would not say cratered primers is a high pressure indicator, when seen with other pressure signs, certainly it is but if its by itself, generally its a firing pin and hole dimension issue and unless it really bothers you, can just be left alone. [/QUOTE]
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