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So if the primer is seated to 0.008 deep then how can it slam fire?

I think that the floating firing pin is the problem. Look at the primer of a round that has been chambered and you can frequently see a slight indentation from the firing pin. Putting a round into the chamber and then slamming the bolt forward makes it more likely.

The only slam fire I have ever had was from a high primer.
 

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I think that the floating firing pin is the problem. Look at the primer of a round that has been chambered and you can frequently see a slight indentation from the firing pin. Putting a round into the chamber and then slamming the bolt forward makes it more likely.

The only slam fire I have ever had was from a high primer.
What I am saying is, I use 210M Primers in Lapua and WCC10 Brass seated to 0.008 deep and there is no indentation. None at all. Every case I check has no indentation. So when the primer is seated to the correct depth you won't have any problems.

As for dropping the bolt on a round in the chamber with no magazine inserted. Well you are going to have problems. The manual strictly warns not to do that.
 

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Who labeled the thread 'slam fire argument'? This is the first time I've heard about countersinking primers too. If a firing pin free floats it obviously is free to strike a countersunk primer if it's free to ignite it upon deliberate firing. What does .008in get you? Soften the blow of a non hammered strike??
 

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Who labeled the thread 'slam fire argument'? This is the first time I've heard about countersinking primers too. If a firing pin free floats it obviously is free to strike a countersunk primer if it's free to ignite it upon deliberate firing. What does .008in get you? Soften the blow of a non hammered strike??
Grab a case and seat the primer to 0.008 and see if you get that indentation. I guarantee you won't. Here take a look at this thread
http://m14forum.com/ammunition/97799-primers-question-m14-s-2.html#post684475
 

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Does anyone know of a publication or other technical description of the differences between the US Military #34 and #43 primers?

Ray
Nope I do not know of any publication about the primers. I have heard though that Military primers are a bit harder, thus helping against slam fires due a floating firing pin.

I have been shooting the M1 Garand since the early 90's and reload for it, I only have experience two slam fires and I can confirm that both slam fires were caused by protruding primers. I do not bother using CCI #34 or #41, I use Winchester LR primers.
 

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I just make sure the primers are below flush and never had an issue. I do use CCI 34 primers for reloading .308 and 30.06. That's what I was told to use when I started and what was used for load development.

I still wish they made CCI 34/41 with nickel plating because it is easier to see that the primers are indeed below flush.
 

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Well, it looks like this has devolved into the age-old argument about slam fires, so I assume no one can answer my question?

Ray
I thought your question was already answered when it was pointed out that one is for large rifles and one is for small rifles. That is all the technical information you need to determine whether you should use a #41 or #34 primer in a specific round.


Shooter, I am glad you do not get indentations. Some of us, however, do get indentations even when the primer is seated below the base of the case.
 

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Well, it looks like this has devolved into the age-old argument about slam fires, so I assume no one can answer my question?

Ray
Military-style semi-auto rifles seldom have firing pin retraction springs. If care is not used in assembling ammunition, a “slam-fire” can occur before the bolt locks. The military arsenals accomplish this using different techniques and components—including different primer sensitivity specifications—from their commercial counterparts. CCI makes rifle primers for commercial sale that matches military sensitivity specs that reduce the chance of a slam-fire when other factors go out of control*. If you’re reloading for a military semi-auto, look to CCI Military primers.
*Effective slam-fire prevention requires more than special primers. Headspace, chamber condition, firing pin shape and protrusion, bolt velocity, cartridge case condition, and other factors can affect slam-fire potential.
FEATURES & BENEFITS:

Mil-spec sensitivity
Initiator mix optimized for ball/spherical propellants
Available in large (No.34) and small (No. 41) rifle
Use the same data as CCI Magnum primers

View Usage Chart
USAGE:

Military-style semi-automatic rifles
http://www.cci-ammunition.com/products/primers/primers.aspx?id=30
http://www.cci-ammunition.com/products/primers/primer_chart.htm
No.41/5.56MM

Military small rifle primer with NATO sensitivity.

No. 34/7.62MM

Military large rifle primer with NATO sensitivity.


Small Rifle Standard

CCI 450 - same thicker .025" cup as the BR4 and #41.
CCI #41 - commercial version of the fully-qualified DOD primer for use in U.S. military ammo. With this primer there is more 'distance' between the tip of the anvil and the bottom of the cup than with other CCI SR primers. .025" thick cup. Same primer mix as CCI 450.
Remington 7 ½ BR - A match or "bench rest" primer. Hornady, Handloads.com, and Chuck Hawks classify this primer as a Magnum, differing from other sources that classify it as a Standard. .025" cup thickness.
Wolf/Tula Small Rifle Magnum SRM - hard, less sensitive brass cup intended for AR15/military rifle and high pressure rounds - #KVВ-5,56M.
Wolf/Tula Small Rifle 223 SR223 - #KVB-223M "This is the newest primer available in the Wolf line. It is ever so slightly hotter than the small rifle magnum primer and it comes with a brass colored thick cup. This primer can be used in place of the SRM primer or used when a different powder is used that is hard to ignite."
 

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I'm the one who changed the title of the thread. It's my thread so I guess i can do that? If there was a way, I'd simply delete the thread and start over.

For some reason, many of you keep referring to the #41 primer. I am not interested in it. I was trying to learn the differences between the #34 and the #43, both milspec LR primers.

Ray
 

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I hope somebody can come up with the actual spec data.
 

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The Large Rifle primers used in Lake City ammunition are the #34 for normal combat ammo, and the #43 for Match ammo such as the M72, M118 M852 and M118LR. The #34 roughly corresponds to a Large Rifle Magnum, while the #43 is equivalent to a Large rifle Match primer. Both use thicker or harder cups to preclude slamfires, as has already been pointed out.

Jim
 
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