Primer Preload

Roger T

Roger T

Member
Is there a "best" preload on primers ? Currently when seated I have .002 crush using Wolf LR .128 fresh from box .126 seated, pockets are .128 deep.
 
No, there's no better way to seat primers. Just seat them metal to metal and that's the best you can do.
 
I hate to disagree with wilbur, but the .002 crush after bottoming out
has been mentioned several times. I think it came from a mil spec somewhere in the past.
 
Everyone that I am aware of in this sport seats primers by feel, not by depth, most using hand tools. On the other hand, when setting up automatic machinery, one would have to have some sort of specification. Everyone who shoots factory ammo in competition please hold up his or her hand. Next question ;-)
 
No problem with the disagreement..I don't know much about Mil Specs but I'm pretty sure .002 is ok too. Not better but OK too.
 
No,
but lacking input from primer makers, input from a large user of primers might bear some consideration.

ebb said:
Mil spec is the highest standard for loading benchrest ammo?
Click to expand...
 
I believe you just

ebb said:
Mil spec is the highest standard for loading benchrest ammo?
Click to expand...

described the ultimate of "lowest common denominator". Mil-Spec is nothing more than the minimum the Military will accept in their attempt to make sure they lose less soldiers than their enemy.
 
ebb and David,
Can you provide a primer makers installation instructions ??
WHILE WHINNING ABOUT MILSPEC AMMO, neither have provided any positive input to the questiom.
 
Roger T said:
Is there a "best" preload on primers ? Currently when seated I have .002 crush using Wolf LR .128 fresh from box .126 seated, pockets are .128 deep.
Click to expand...

I shot the (Russian) primers for ten years in the 308 Palma Game, the Russian primers are larger in diameter that US made. The Russian primer must be sensitized after hitting the bottom to instill a bit of crush to the primer or the SD's of the load will suffer. The .002 you mention may be a little on the light side, I will test it and report.
 
Wilbur is correct. Just seat the primer until it touches the bottom and stop. That is if you are looking for Benchrest accuracy. Continuing to seat the primer once it bottoms out is detrimental to accuracy. John Gammuto wrote an article on the subject some years back and I have proven it with my own experience.

Im pretty familiar with "military specs". The military's primary concern is that a cartridge fires everytime. Some crush on the primer to make sure it's seated as far as it can go makes sense. It's not a standard to enhance accuracy, but reliability.

Bart Sauter

Bart's Bullets
 
Last edited:
Bart said:
Continuing to seat the primer once it bottoms out is detrimental to accuracy. John Gamuto wrote an article on the subject some years back and I have proven it with my own experience.



Bart Sauter

Bart's Bullets
Click to expand...
Is this due to cup/anvil deformation ? Is there a link or publication I can look at of this.?
 
Roger T said:
Is this due to cup/anvil deformation ? Is there a link or publication I can look at of this.?
Click to expand...

My guess would be that it's deforming something. However, I'm not much of a "why" guy, I go for results. My first shooting mentor Martin Menke, a German tool and die maker would tell me, " I don't know why it is, but it is." John's test tried various seating depths from not bottoming out to crush. Best results were from just feeling the primer touch the bottom of the cup. That's what I have found to work the best.

You can find the article in an old Shooters News.

Prove it to yourself and play with different seating depths yourself. I think you'll find the worse groups will be from primers that aren't touching the bottom, crushed will give erratic groups and just touching will be the best.


Bart
 
Bart, Thank you

Bart said:
My guess would be that it's deforming something. However, I'm not much of a "why" guy, I go for results. My first shooting mentor Martin Menke, a German tool and die maker would tell me, " I don't know why it is, but it is." John's test tried various seating depths from not bottoming out to crush. Best results were from just feeling the primer touch the bottom of the cup. That's what I have found to work the best.

You can find the article in an old Shooters News.

Prove it to yourself and play with different seating depths yourself. I think you'll find the worse groups will be from primers that aren't touching the bottom, crushed will give erratic groups and just touching will be the best.


Bart
Click to expand...

for clarifying that. I figured there was some kind of logic to the Mil Spec. Thanks

David
 
I sure cant remember where I read it, but I read that any thing over touching can break the priming compound and alter the intensity of the flame. FBecigneul if you had informed me I could have refrained also. Don't keep these things to your self!
 
Don't mean to be a "smarty pants"

Roger T said:
Is this due to cup/anvil deformation ? Is there a link or publication I can look at of this.?
Click to expand...

But...you just read the gospel....right here. Why would you go anywhere else to read anything about accuracy.
 
+1 to what Wilbur said. If you seek information and a shooter that holds world records and is in the Benchrest Hall of Fame takes the time to give you the information about his method of seating primers........... why would you ask for more? Good shooting...James
 
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