Measuring primer seating depth.

[Rocketvapor]

I do a few different operations by Feel.
Sizing with a body die, Neck sizing with a Collet Die, Primer Seating with a 4 hole press (no advance).
What I find is the mush doing these operations hides the final 'Feel'.
Sizing, I hold, rotate, then hit it again.
With primer seating I can feel seating but rotate the case a little and Feel the bottom better.

 

[Webster]

So.... before I hand someone $$$ for a new " latest and greatest " primer seater I had a thought. How exactly do you measure primer seating depth?

Would be nice to know before I condemn my old RCBS bench primer for a "more accurate one".

Thanks!

No reason to measure. Seat to the bottom of the pocket by feel. All the special tools were invented only for the purpose of getting your money.

 

[barefooter56]

Get the SINCLAIR PT-2000 priming tool (on sale at an excellent price right now!) Or a PMA priming tool. Both lock the case in a straight line with the priming ram and have an excellent "feel" in regard to primer " bottoming out" in primer pocket.

 

[6ShotsOr5?]

The short answer to the question “how do you measure primer seating depth” is I use a caliper, but I only measure when I think the primer could be protruding. The details will put you to sleep, but at least you’ve been warned.

Just to help me learn how I wanted to process my brass, I measured ten 205M primer heights and ten new brass Lapua 6BR Norma primer pocket depths with a caliper just to see if the pockets were always deep enough — they weren’t. I probably would have measured at least 50 or 100 of each but when the size distributions overlapped with small samples, measuring more wasn’t necessary. Then I measured some primer pockets from my fired cases and found that they were a little shallower after firing (as expected, per some reloading manual I read). Also I have observed that the uniformer will always cut a little more brass after each firing — I’m pretty sure most people see the same thing. So I learned that I either needed to uniform my pockets to make sure they are deep enough (and do it each time I load these cases), or cull a few tall primers, or use shorter primers (some CCI are shorter than the 205M). I wanted to stick with the 205M since I just bought several bricks. For me it’s easier to uniform the pockets on my Lyman prep center at the same time I’m brushing the inside of the necks than it is to to measure primers and only uniform a few pockets so I can use the tallest primers.

My uniformer has a shoulder that acts as a stop at ~ 0.014” per Mitutoyo caliper (not an adjustable depth uniformer) which is deep enough for very near 100% of my primers to be flush before crushing, and the primers are all short enough after putting a little crush on them. It makes me wonder if that uniformer depth was designed specifically for 205M primers and Lapua small rifle primer brass. I also like it because it has channels on the sides which keep the brass chips flowing out of the way so I don’t need to brush them off the tool very often.

RCBS Trim Mate Case Prep Center Carbide Primer Pocket Uniformer Small

The RCBS Trim Mate Case Prep Center helps to make the tedious tasks of chamfering, deburring, primer pocket cleaning, military crimp removal and flash...

www.midwayusa.com

After seating each primer, I also visually check the case head area and touch the bottom of the case to see if it feels right. If I can’t feel the slight indention at the primer with my fingertip, it gets measured. I only find a “barely” high one maybe every 500 or more rounds.

I probably have some OCD issues but I’m not doing those things out of a desire to get the primers all seated exactly the same or because I think it’s gonna show up on target. I just want to keep things as simple as I can AND do whatever is necessary to avoid having protruding primers. A protruding primer always seems like a bad idea, and this seems even more true with very little shoulder bump and when jambing bullets.

I appreciate that there are lots of others using the same brass and same primers and some of them have said they do not uniform the pockets. Hard to argue with their success so I’m still learning. As @jackieschmidt said, he’s only using his PPC cases 3-4 times, but I’m using my 30-BR cases 15-20 or more times. This undoubtedly has some impact on whether the pockets may need to be at least occasionally uniformed. And the idea of standing the cartridge on a flat piece of glass to find the high ones is very practical too. But, I’m really not trying to find the high primers as much as I’m trying to avoid having them.

 

[RegionRat]

There is more than one kind of primer design in the Boxer world, and we still can see two or three foot anvils, and for unknown reasons they never come with installation instructions.

The lack of direct design information for primer installation baffles me cause it would take nothing to print it on the box or their websites. Be that as it may....

As someone who was formally indoctrinated in design development and testing of primers and initiators of many kinds, I will tell you all up front that the majority of the primers you find with an anvil foot that slightly protrudes from the cup is intended to be installed with a "crush" to those anvil feet of 0.002" - 0.006".

There are on occasion primers that have flush anvils, and those are to be inserted to bottom the cup.

Here is a snippet of public domain specification that I am allowed to share as an example. What they are calling "reconsolidation" is what this forum often calls "crush".





When a device is added to measure the primer output performance, you can observe the consequences of not using the recommendations. The spread of the blast energy will not be as consistent as when installed to specs. The performance is not very sensitive once the anvils are touching, but they are improved by crush within their recommendations. So, don't expect to find a difference on the target for the difference between crush of 0.002" versus 0.006", but with enough of a sample you will find the difference of seated that accidentally leaves the anvil short of the bottom or just barely touching the bottom versus 0.002" - 0.006". YMMV

 

[misser]

If you've got a good caliper and are somewhat skilled with it, you use the end with the tiny protrusion that comes out at the bottom when you open the caliper to measure depths. It take a little skill to get a consistent measurement.

OR . . . if you want fast and accurate, you can hand over some more $$$ with the Accuracy One tool :

Precision Primer Gauge

The Precision Primer Gauge takes precision measurements of primer pocket depth and the depth of seated primers in relationship to the face of the case head.

bullettipping.com

I did, not sorry

 

[misser]

was it Accuracy One that said the primer should touch + .002 for crush making it .007 below flush ?

 

[JFrank]

There may be too many variables to call out a generic number of .xxx below flush.
Right or wrong, I did a little testing with my click adjustable 21st century primer tool using a target of multiple aiming points I increased the amount of crush with each click to find a nice little crush window by feel that shot well.

 

[Webster]

There is more than one kind of primer design in the Boxer world, and we still can see two or three foot anvils, and for unknown reasons they never come with installation instructions.

The lack of direct design information for primer installation baffles me cause it would take nothing to print it on the box or their websites. Be that as it may....

As someone who was formally indoctrinated in design development and testing of primers and initiators of many kinds, I will tell you all up front that the majority of the primers you find with an anvil foot that slightly protrudes from the cup is intended to be installed with a "crush" to those anvil feet of 0.002" - 0.006".

There are on occasion primers that have flush anvils, and those are to be inserted to bottom the cup.

Here is a snippet of public domain specification that I am allowed to share as an example. What they are calling "reconsolidation" is what this forum often calls "crush".

View attachment 1608163

View attachment 1608168

When a device is added to measure the primer output performance, you can observe the consequences of not using the recommendations. The spread of the blast energy will not be as consistent as when installed to specs. The performance is not very sensitive once the anvils are touching, but they are improved by crush within their recommendations. So, don't expect to find a difference on the target for the difference between crush of 0.002" versus 0.006", but with enough of a sample you will find the difference of seated that accidentally leaves the anvil short of the bottom or just barely touching the bottom versus 0.002" - 0.006". YMMV

I always assumed that if the primer anvils extended outside of the cup so that when you seated by feel the cup contacted the bottom of the primer pocket and you couldn’t seat it any deeper because you cannot crush the cup itself. Thus, the cup limits how far you can push the primer into the pocket. They are all done the same. Do you think this is accurate. If the anvils don’t extend outside of the cup, the cup bottoms out in the pocket preventing further movement. If you seat by some arbitrary distance FP force may be absorbed while pushing the cup forward against resistance. I have been seating by feel for 50 years with my $5 Lee hand tool and I am happy with my varmint rifles shooting small groups.

Let the flames begin.

 

[RegionRat]

Do you think this is accurate.

Try measuring the anvil height above the cup. Most designs with feet that extend are not designed to crush those anvils flush to the cup.

Folks are still free to do what they want... at least for the time being....

Seat by feel or by inspection, if you are happy then I am happy too.

I would never tell someone experienced anything about this unless asked, and even then there are legal limits to what I can share.

When teaching our technicians or rookies, I don't let them seat by anything other than inspection when hand loading. Production lines are machines and do what we set them to do.

I will add this... whenever I have handed friends that primer seating gage and we checked their workmanship, every one of them found they were not seating all of their primers to the bottom or to a consistent crush.

For some of those same folks, we bumped those primers down with a good quality hand tool to try and get a nominal 0.004" crush, and those folks all discovered an improvement in their ES/SD.

I'm just trying to pay it forward and only mean to help. YMMV

 

[misser]

I always assumed that if the primer anvils extended outside of the cup so that when you seated by feel the cup contacted the bottom of the primer pocket and you couldn’t seat it any deeper because you cannot crush the cup itself. Thus, the cup limits how far you can push the primer into the pocket. They are all done the same. Do you think this is accurate. If the anvils don’t extend outside of the cup, the cup bottoms out in the pocket preventing further movement. If you seat by some arbitrary distance FP force may be absorbed while pushing the cup forward against resistance. I have been seating by feel for 50 years with my $5 Lee hand tool and I am happy with my varmint rifles shooting small groups.

Let the flames begin

did it that way for 50 years this thing came out I have not looked back

 

[Chiquita]

Precision Primer Gauge

The Precision Primer Gauge takes precision measurements of primer pocket depth and the depth of seated primers in relationship to the face of the case head.

bullettipping.com

i know folks who measure using the depth gauge on their caliper.

I use one of these & my own made stand plus CPS & Century 21st hand primer.

 

[Webster]

Try measuring the anvil height above the cup. Most designs with feet that extend are not designed to crush those anvils flush to the cup.

Folks are still free to do what they want... at least for the time being....

Seat by feel or by inspection, if you are happy then I am happy too.

I would never tell someone experienced anything about this unless asked, and even then there are legal limits to what I can share.

When teaching our technicians or rookies, I don't let them seat by anything other than inspection when hand loading. Production lines are machines and do what we set them to do.

I will add this... whenever I have handed friends that primer seating gage and we checked their workmanship, every one of them found they were not seating all of their primers to the bottom or to a consistent crush.

For some of those same folks, we bumped those primers down with a good quality hand tool to try and get a nominal 0.004" crush, and those folks all discovered an improvement in their ES/SD.

I'm just trying to pay it forward and only mean to help. YMMV

I like reading all of your post and replies. Just making some assumptions about whats going on. I don't shoot competition. Just trying to get a discusssion going about whats going on. Both my rifles shoot under .400" so I am happy with results.

I have not examined a primer recently. Do you think that when the wings of the anvil contact the pocket they are just getting bent and the point of the anvil isn't moving into the primer compound? The anvil never contacts the primer compound. There is a foil disk between the anvil and the primer compound. I have read where all the primer manufacturers say seat to the botton of the pocket.

 

[RegionRat]

Do you think that when the wings of the anvil contact the pocket they are just getting bent and the point of the anvil isn't moving into the primer compound?

The anvil definitely compresses the pellet.

 

[danny]

tmwinds nailed it. Primers are designed to be seated so they bottom out in the primer pocket. This insures proper ignition. The people making those adjustable primer seating devices are fooling reloaders (SOME RELOADERS) into thinking that primers have to be seated to a depth different than being seated until they bottom out in the pocket.

Have you ever had a problem with seating primers that way? If not, then why change anything?

Save your money, buy beer instead.

See comment above.

Danny

 

[6MMsteve]

Me too.

Me 3

 

[Richard Jones]

Another point of view......
Dusty's Primer Seating Method

 

[Webster]

See comment above.

Danny

I would guess that the FP provides plenty of crush.

 

[Rat Rifle]

Some have tested various amounts of primer crush. Worthwhile reading if you have not read the results.

In My opinion, primer “crush“ is a separate issue. It is the amount of force applied to the primer after it bottoms in the pocket.

 

[danny]

Some reloaders seem to be happy with seating to a dimension as compared to just bottoming the primer in a given primer pocket. Unless you primer pocket uniform and possibly control other dimensions, you are probably just seating some in a crushed condition, some just right, and some not deep enough, but hey, you got that exact dimension below flush that you wanted. Isn't that the most important condition?

Danny