primer question

I’d doubt few could supply an answer to that. I would personally drop back to the starting load and go from there assuming you developed the load initially.

Reduce your standard load by 10% if using magnum primers and work up from there. Increase a 1/2 grain at a time while watching for increased pressure signs. Very possible you can use your standard load with magnum primers if you work your load up to it. Others may tell you that it's OK to just switch primers, but that has not been my experience. Be safe my friend!

loadedround said:

Reduce your standard load by 10%

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If his "standard" load is on the lower end, and he reduced it by 10%------couldn't that become an issue.....?

Doesn't 5.56 already call for a small magnum rifle primer?

If your not a max you will be fine. Just drop back 1/2-1 gr and work back up. 556 runs in the 60k-62k psi range so std primers are fine but some fail before others. Federal fail first since they use a thinner cap.

I went to the small MAG rifle primers in the 223 for my AR's. I dropped one grain and worked back up. It was virtually the same load that would have worked but the accuracy demanded I drop it by .1 grain. That was with CCI and Win small MAG primers.

You do really need to drop back some and work up at least for accuracy sake.

loadedround said:

. . .Be safe my friend!

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Key phrase ^ ^ ^ right there ^ ^ ^

bersaguy said:

Doesn't 5.56 already call for a small magnum rifle primer?

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According to Midway and some other resellers, "[...] CCI Number 41 Mil-spec primers are made to the same specifications of the U.S. Military and reduce the chances of a slam-fire. While designed for Military-style semi-auto rifles, they use the same data as CCI magnum primers." I checked the CCI site and there is no such matching declaration to, "...use the same data as CCI magnum primers." All CCI says is they're built to Mil-Spec. Winchester says the same thing but their #41 primers say on the box, "WMSRL" whatever that means. I guess the next question is, are Mil-Spec small rifle primers the same as commercial magnums?

Soonerpesek said:

If his "standard" load is on the lower end, and he reduced it by 10%------couldn't that become an issue.....?

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There's all kinds of variables and a specific answer covering every gun and every load would take a few pages. Bottom line (and good reloading practice!) anytime any component is changed, do another load work up. Some drop 10, some go back to book starting data...