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primer seating depth

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a friend is having issues with soft primer strikes

 

just being technical

using a stand dial mic. comparator  (https://www.midwayusa.com/product/310955/rcbs-case-master-concentricity-gaging-tool) 

i measure bottom of case for lowest reading then zero

then measure primer surface

 

 

what is (rule) specification for primer seating depth?

 

this is on 9mm

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On what kind of gun?

 

With a Glock and M&P, even with slightly lighter striker springs, I always adheared to "if it's flush, then it's good." 

 

When setting up my first hammer fired DA/SA gun I learned this isn't really true. FULLY seated in 9mm is usually .005" - .008" below flush. A gun with a light hammer spring will often set off a buried CCI, and choke on a flush Winchester.

 

(If you're not aware, CCI primers are harder to ignite than Winchesters on an equal playing field.)

 

For an extreme example, look at what the wheelgun guys do in order to shoot something with a light trigger pull. This is necessary with federal primers, even:

 

Edited by MemphisMechanic

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With normal tolerances, the primer face should be 0.003 to 0.005 inches below the case, though I have seen factories allow anything from 0.000 to 0.008 inches.

 

Overall, what you want is the primer anvil legs against the bottom of the primer pocket.

 

The three to five thousandths usually gives reliable performance.

 

Guy.

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Thanks all. I measure a few of mine and got .003 avg..    

 

Next question ion my friend loads on a 650 ( I load on 550). 

 

What could be going wrong other than bad QC ?

 

 on 550 I'd look at primer cup adjustment ,.

 

I know little to nothing if 650.

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Did any of the light primer strikes fire on a second try?

 

The 0.003" should be suitable unless the anvil legs are not against the bottom of the primer pocket.  This could be that primers are on the shorter side and/or the primer pockets are on the deeper side.

 

You might try one or two things.  First - how does it do with factory ammunition?  If factory ammunition gives the same problems you may suspect the gun,

 

Alternately, load a batch of ammunition and sort by primer seating depth, looking for a group 0.005 - 0.006 inch deep see how they work in the gun.

 

Guy

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What are these being shot through? Does it have a factory hammer/striker spring?

 

What brand of primer is being loaded?

 

There is no adjustability on the 650 for the priming mechanism. The punch seats them as deeply as it seats them, and that's the end of it. I've tried several fixes to make my 650 drive primers all the way home, and not even shimming the primer ram has helped.

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Factory guns/ springs.

 

cci primers... ( I'll confirm tomorrow) 

 

small percentageage fuctioned on second strike.   Saved most to analyze.

 

100% on factory ammo

 

100% on my reloads ( 550, Winchester primer, mixed brass, title group) 

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Sounds like you friend just isn't pushing hard enough on the handle to seat the primers.

 

Don't bother measuring, just seat them fully in the case.

 

You might make sure that the primer punch hasn't loosened up and backed out a bit.

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he got back to me and said he found a loose primer while cleaning the 650..

 

he thinks this was the problem....

 

 

thanks  all

 

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If this is the same friend who is having a problem with light charges and if the loose primer doesn't solve both issues, he'd be well advised to re-evaluate his reloading procedures before something more serious happens.

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