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More primer Questions


Rbelote

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I have found plenty of magnum small pistol primers. How will they change a load? How much will the raise the power factor? Are they harder to detonate than regular small pistol primers? DO they put out more pressure and get the bullet moving before the powder is lit?

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They are slightly harder to detonate than a regular primer, 'cause they're slightly harder. They will increase pressure. They should not be used with extremely fast powders like bullseye, clays, N310, etc., to avoid unpredictable pressure spikes. If you want to sub them for regular primers the only way to do so safely is start with a reduced charge and work up cautiously observing for indications of overpressure and, preferably, observing changes in velocity using a chronograph. The amount a mag primer might change your PF is an equation with too many variables to figure out in any way other than with the use of a chronograph.

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I have read/heard about different cup harness for a long time. I remember reading somewhere that the main difference between small rifle primers and small pistol primers is the charge, not the hardness. Also that the difference between Federal and the rest has to do with the volitility of the primer substance, not the cup. Federal uses a more sensitive material. I would assume that just like small rifle primers are designed to ignite more powder, magnum small pistol primers are likely the same.

What I would really like to see is someone do an independent testing of the actual impact forces required to detonate the major brands of primers and also to take the cups and do a hardness test on them. We could put all the internet speculation to bed once and for all.

Then again all the rumor and inuendo is what makes the internet so much fun, why ruin it?

Jim

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Magnum primers, whether small or large, increase temperatures to facilitate ignition and burning powder in magnum cases and are suggest for certain ball & spherical powders. Magnum primers when substituted for regular, will increase pressure. Therefore your loads should be reduced accordingly.

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I bought 1000 magnum small pistol primers by mistake. When I chrono'd them I got 10-20ft/sec faster from what I recall. No other signs. I don't use hot loads.

Edited by lugnut
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A buddy and I split a large order of Fed. SPM primers. He recently loaded some under HS-6 for his open glock, and compared them to other rounds loaded with Fed.SP, otherwise identical load. The magnum primer loads averaged 30 fps SLOWER than the standard SP primers. Anyone got an explanation for that one?

-br

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