Primer seating depth and primer seating force

[dr foxtail]

Pretty sure that would be way too much. You'd be smashing the primer to a point where it could not be smashed anymore. No fancy tool or feel or measure needed for that much.
When I seat primers too deep, I get flyers. But that's not with a 6PPC..

I agree it's too much but
1) apparently that's how Federal says to seat them per an earlier entry in the thread which is what prompted my comment and
2) that's exactly what he is showing in his drawing on the right side, the 450 primers, the cup is bottomed out in the pocket.

 

[Sixgun]

K&M Primer Pocket Unforming tool after depriming....Nothing to worry about. It chips out the carbon as it maintains the dimentions so you're not seating primers on a layer of carbon.

 

[BoydAllen]

That is only the case because in his example the primer pocket is the same depth as the total thickness of the primer (cup and anvil).
The current brass I'm working with has pocket depth of .124 and the 450 primers I have are .117 total and .112 cup only. That means I need to seat my primers .007 below flush just to get the feet to touch the bottom of the pocket and .008 below would result in only a .001 crush with a maximum crush of .005 when the cup bottomed out in the pocket. In addition the bottom of the primer pocket is narrower than the opening by .004 meaning I really have to push them hard to even a little crush so hard that it is deforming the exposed bottom of the cup. There is a little circular protrusion. See picture.
Based on the picture from the SAAMI book earlier in the thread, the thickest allowable primer doesn't fit in the shallowness allowable pocket without a .009 crush and at that rate it is only flush. Even the deepest allowable pocket requires a .003 crush to be flush.
I know that's a lot for an old thread but I just got this CPS seater and I'm trying to figure things out.
Thanks for putting up with me.

I don't know if you saw it, but I actually called CCI and asked one of their technicians what they recommend. He told me, in no uncertain terms that they recommend seating so that the bottoms of the anvil feet are flush with the edge of the cup. I suggest that you try different amounts of pressure using your favorite hand tool, seating primers in the same pocket, measuring the resultant depth, and then removing them to look at where the bottoms of the anvil feet are in relation to the edge of the cup. I have done a little of that and in my experience it takes a lot of pressure on a hand tool to achieve their recommended seating. The other think that I noticed was that with a primer seated that way, I could see no evidence of damage to the pellet, or the cup. To be able to see the position of the anvil feet, I trapped the primer in the jaws of my dial calipers and used a 20X loupe.

 

[TylerFromMS]

@BoydAllen Do you feel like the anvil stays in the same place after the primer is removed? This is something I hadn't thought of and sounds interesting. I've been using a good old fashioned outside mic for the primers and a depth mic stuck down through a shellholder for the primer pockets to measure.

I have done a little of that and in my experience it takes a lot of pressure on a hand tool to achieve their recommended seating.

And here we are full circle back to the $600 priming tool

 

[BoydAllen]

@BoydAllen Do you feel like the anvil stays in the same place after the primer is removed? This is something I hadn't thought of and sounds interesting. I've been using a good old fashioned outside mic for the primers and a depth mic stuck down through a shellholder for the primer pockets to measure.


And here we are full circle back to the $600 priming tool

I do. There seems to be a lot of friction between the sides of the anvil feet and the inside of the cup. Play around with some fired primers and I think you may come to the same conclusion. It takes very little force to remove a primer and I believe that I have a sensitive feel. I do not jerk on the handle or rush things. I bring it down until I barely feel the primer, and then slowly remove it. If you do this, be cautious. Wear eye protection. Until I got quite a bit of experience, I would hold up a piece of wood or a thickly folded bath towel between my face and the case. I have never set one off in many years of doing it.
On the $600 dollar priming tool. All of the HOF members and record holders that I know seat by feel. I think that there is a lot of merchandising going on. People want to be told that more complicated and expensive things will shrink their groups when in fact they need to buy a set of flags, tune at the range, and learn how to keep their loads in tune as conditions change, but that is just my opinion.

 

[TylerFromMS]

I do. There seems to be a lot of friction between the sides of the anvil feet and the inside of the cup. Play around with some fired primers and I think you may come to the same conclusion. It takes very little force to remove a primer and I believe that I have a sensitive feel. I do not jerk on the handle or rush things. I bring it down until I barely feel the primer, and then slowly remove it. If you do this, be cautious. Wear eye protection. Until I got quite a bit of experience, I would hold up a piece of wood or a thickly folded bath towel between my face and the case. I have never set one off in many years of doing it.
On the $600 dollar priming tool. All of the HOF members and record holders that I know seat by feel. I think that there is a lot of merchandising going on. People want to be told that more complicated and expensive things will shrink their groups when in fact they need to buy a set of flags, tune at the range, and learn how to keep their loads in tune as conditions change, but that is just my opinion.

Interesting, I’m going to have to try it. I’ve deprimed a number of live primers but it’s never occurred to me to measure a primer afterwards. Thanks for that info.

As an aside, you can seat by feel with the CPS. Also, according to the game you play, changing loads as conditions change at the range throughout a competition may not be an option.

 

[BoydAllen]

Interesting, I’m going to have to try it. I’ve deprimed a number of live primers but it’s never occurred to me to measure a primer afterwards. Thanks for that info.

As an aside, you can seat by feel with the CPS. Also, according to the game you play, changing loads as conditions change at the range throughout a competition may not be an option.

To be clear, I was only using the calipers to hold the primer so that I could examine it with the loupe. This was to determine if the bottoms of the anvil feet were flush after seating. Two were, a third had a tiny bit showing below. The seating force was all that my big old hands could muster with a 21st Century tool. A while back, I measured a few loaded Lapua BR cases that have not had their pockets uniformed. The primers were 205s and if memory serves they were all around .009 deep, and pretty consistent. To repeat myself, I seat by feel. I saw no damage to the pellet, or flattening of the top of the cup.

 

[TylerFromMS]

The seating force was all that my big old hands could muster with a 21st Century tool.

I could see that. And we load 200-400 at a time . That’s why I was referencing the expensive primer.

Thanks again for the ideas. I’ve got some loupes I use for chamber inspection and I think they’ll work great.

 

[mikecr]

I think that there is a lot of merchandising going on.

It's merchandising that leads a notion of feeling instead of measuring,, right?

 

[BoydAllen]

It's merchandising that leads a notion of feeling instead of measuring,, right?
View attachment 1472900

IMO the opposite, since virtually all tools can be used to seat by feel. Similarly there is no profit to be made by suggesting leaving Lapua primer pockets unmolested.

 

[mikecr]

Someone suggested NOT uniforming Lapua pockets?

 

[JFrank]

After a bit of testing both molested and unmolested pockets with just light cleaning, I haven’t seen much difference as long as I’m in my crush/ depth window. IMO there are bigger knobs to turn.

 

[jimmymac]

Still using the old Lee Autoprime with no issues. This year I decided to stop messing with primer pockets in my Lapua cases. I don't even clean them anymore. I've seen no difference on target. I've had a pretty decent season. KISS YMMV

 

[wildcat3d]

 

[coldboreshot]

 

[mikecr]

When you swap primers, they all go off, but grouping opens & closes with testing.
When you adjust primer crush, which includes pocket depth & primer height, grouping opens & closes.
When you adjust striking, pin fall, diameter or mass, or spring, grouping opens & closes.

You may not notice this at 100yds, but if you're not testing it at distance, you're likely leaving something behind. You could suggest that so & so won once with mud packed under his primers. But that doesn't mean he couldn't have won, or done even better that weekend with more efforts.

I don't believe ignition affects grouping only, but SD as well. Another attribute to watch with testing.

 

[JFrank]

@mikecr
Sir, who are you referring to when you say “ you”?

 

[mikecr]

When YOU

 

[JFrank]

When YOU

Thanks for the clarification, it felt that you were directing your comment my way. I’m fairly comfortable with my testing results and that’s why I am willing to share but also willing to learn so thank you for your post.
I’m just a little fuzzy on which 1000 yard competitor you are ?
I’m also a fuzzy on how a minor primer crush adjustment significantly opens and closes long range grouping ?
My testing just doesn’t support that, perhaps YOU can share your targets shot at “distance” that do ?

 

[Bill Norris]

Still using the old Lee Autoprime with no issues. This year I decided to stop messing with primer pockets in my Lapua cases. I don't even clean them anymore. I've seen no difference on target. I've had a pretty decent season. KISS YMMV

Still using the Lee Bench Primer. I do clean the primer pockets but truthfully I don't think I would see a difference in group size if I did not clean them.