Primer seating squish

F

fishbone

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Re-reading Tony Boyer's book I took note that he says to seat a primer to where it touches the pocket bottom. And, not to "squish" it.
I thought I had this question sorted out in my mind to where the primer is seated, and then given that extra force to mash it in place. I figured that the protruding anvil was intended to be seated even with the cup edge, hence the mash sensation with the extra effort.
Any thoughts here?
 
Not talking from a short range perspective, but all my loads have improved since my arthritis got so bad I couldn't feel the primers in any more & I changed over to a K & M seater with the dial gauge on it. I've used their recommendation which was .003" squish on LR & .002" squish on SR primers.

Man, does it take a l-o-n-g time to prime now!
 
John, I can see where the operating takes much more time. If I'm reading the K & M instruction correctly, each primer is calibrated for, then seated by creeping up on the dial indicator target setting with the chance of over shooting. Wow.
However, I understood where they too are saying not to mash the anvil, which agrees with Tony.
I believe I read somewhere (I read too much) a post quoting a manufacture's spokesman that the anvil should be crushed.
This is why I'm confused.
It seems like a seater with an adjustable stop would be a good compromise if I knew where to set the depth.
 
Primers vary in thickness, which is why setting to a standard depth below the case head will not get you there. It should also be mentioned that there have been numerous reports that the Russian primers, which have a different priming compound, require very firm seating for reliable ignition. The ones that I tried produced very good results, it is just that evidently they take a different approach from the one that Mr. Boyer mentions in his book when seating.
 
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John Kielly said:
Not talking from a short range perspective, but all my loads have improved since my arthritis got so bad I couldn't feel the primers in any more & I changed over to a K & M seater with the dial gauge on it. I've used their recommendation which was .003" squish on LR & .002" squish on SR primers. Man, does it take a l-o-n-g time to prime now!
Click to expand...

John: Here's a cure I found for the arthritis problem: http://www.forsterproducts.com/catalog.asp?prodid=700679 You can use the meaty part of your palm as the driving force.
 
Ok so if primers vary in thickness....
Then using a primer seater that can be set for a certain depth like the sinclair, cnetury 21 or K&M shouldnt we be able to sort our primers for thickness? Not that I really want one more thing to add to the process but if it really made a difference.....
 
All that 'squishing" does, in theory, is ensures contact between the anvil and mixture and "sensitises" the mixture which makes the primer better/worse/the same. Your choice.:rolleyes:
 
Vern said:
Ok so if primers vary in thickness....
Then using a primer seater that can be set for a certain depth like the sinclair, cnetury 21 or K&M shouldnt we be able to sort our primers for thickness? Not that I really want one more thing to add to the process but if it really made a difference.....
Click to expand...

The cups and anvils both vary in thickness. One could take them apart and separate them with respect to thickness and priming compound weight. That's three more things...
 
Vern,

The K & M with dial does allow you to measure each case for depth/thickness/whatever of the primer relative to the depth of the primer pocket measured from from the base of the case (not the rim cutout). When correctly used, the anvil end of each primer is identically seated to the bottom of the primer pocket.

Of course, if you don't clean pockets.....

John
 
K&M says (in the instructions for the tool that John uses) that the reason for seating small rifle .002 deeper than just bottomed is because the primer pellet dries out after manufacturing, (assembled wet) and shrinks away from the anvil. I think that I will just pay a little more attention to how I mash them. Sounds like a windy day chronograph session thing, flush vs just bottomed vs some compression with my calibrated thumb and weighed charges.
 
Boyd and John,
Is this still accurate when the primer pockets are different depths?
As I understand what you are telling me the tool can account for the difference in primer thickness but it appears that by what you are saying that it would only work if the primer pockets were identical in depth measured from the rim or head.
Is that correct.
 
As a follow up.
I have done about 93 cases. 21 of the cases still have some sort of deficiency, uncut area right around the flash hole. There for 21+% at this point are not uniform.
I know we tend to throw away brass that does not measure up BUT Ill be danged if Ill accept a 21+% loss. When I pay almost $100 for a box of brass if I have to throw away almost 1/4 or 25% there is something wrong with that.
I am thinking about extending the cutter another 1/2 thou or so to get them to all clean up the same. Might be a little more or a little less. I dont know till I try it.
What do you think.??????????
 
First time I ever heard of a rejection rate for uniforming primer pockets. Uniforming means making them all the same, so how could some be good and some bad????

If all that you are worried about is a small area around the flashhole, don't. The depth is uniform and that little area will probably iron out after one or two full power loads.
 
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Vern,

No. I'll try to explain the process.


  • You clamp a case in the shellholder & slip a primer base up on a mandrel incorporated in the body of the unit. Then you run the ram up until it bottoms hard in the primer pocket - if it happens that the case has a thin rim, no problem, bottoming out sets that relationship. At the same time, the dial indicator comes down on the primer, which you adjust to zero. This establishes the the primer dimension relative to the bottom of the pocket.
  • Take the case out temporarily, remove the primer from the mandrel, flip it & insert above the ram in the usual place. The case returned to the shellholder & locked down.
  • When the priming tool is activated, the dial gauge shows the exact progress of the primer towards seating.


Note that it is independent of the rim & independent (though related to) the depth of the pocket & the depth/thickness of the primer.

John

PS: I just Googled this up (mea culpa) & haven't checked out the details but you should get the idea, http://www.youtube.com/watch?v=xxRZsPjfzHk
 
Vern said:
Boyd and John,
Is this still accurate when the primer pockets are different depths?
As I understand what you are telling me the tool can account for the difference in primer thickness but it appears that by what you are saying that it would only work if the primer pockets were identical in depth measured from the rim or head.
Is that correct.
Click to expand...

The problem I see is that the K&M tool sets primer seating based on the total thickness of the primer, that is, the cup plus the anvil protrusion. On 20 Wolf SRM's, I found that anvil protrusion was 0.008" with an ES of 0.006". With this variation, and using the K&M recommended "crush" of 0.002", the cups are not seated fully to the bottom of the pocket, but are 0.003" to 0.009" short of being bottomed. I am skeptical whether this technique helps accuracy. In particular, I wonder if may be better to consistently bottom the cup in the pocket, so that the firing pin cannot drive the cup forward before it stops. Imagine the inconsistent ignition that might result if some cups slid forward, say in a loose-ish pocket, while others stayed in place. In fact, I didn't find any difference on target in limited testing between seating with the K&M versus seating by feel. YMMV.

Keith
 
Cheech, that spot is there because the primer pocket is not uniform in depth.
I had 100 of the same lot last year and that spot never did iron out, not even with very very full loads.
The spot is caused because they are back to punching primer pockets not drilling them. This can be seen by the concave area in the primer pocket and the convex area on the inside of the case.
There was quite a bit of variance overall in the depth of the pockets.
 
Vern

The primer does not come in contact with that part of the pocket. So, for purposes of primer seating, they are uniform.

Ray
 
Yea I kind of suspected that.
Part of the post was tongue in cheek about how everyone wants to throw away brass. But also sincere about the inconsistency in the pocket area.
They were uneven without just the center around the flash hole.
 
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