How deep should a primer be seated

[RangerTrace]

I thought I knew what a high primer looked like, but apparently flush with the bottom of the case isn't always deep enough.  

 

thoughts?

[Sarge]

I’ve also always thought the same thing. If I can’t feel a bump then it’s good? They always light using that standard for me. I wonder if a certain headstamp has deep pockets?

 Are you positive they are high? Or could it be light springs?

[Ssanders224]

.003-.005" below flush is a good target. 

[MadBomber]

I've always just seated them as far as they will go in.  Haven't had any issues in over 35 years.

[Sandbagger123]

9mm brass is all over the place depending on maker.  some seat deeper than others .  as long as its seated as deep as it will go, and its at least flush , its should go bang

[Farmer]

1 hour ago, Ssanders224 said:

.003-.005" below flush is a good target. 

2X

[99mpower]

i normally progressively set primer depth on my 1050, til it "JUST STARTS" to smoosh, and then back it out a touch. That way you know its fully seated, and its always just under flush. Zero issues. 

 

If you want to get really fancy, you can get a CPS primer, and set primer by .001" increments

[shred]

I feel for a noticeable divot in between the case head and primer.  Flush is cutting it close depending on what you're whacking it with.

 

[ltdmstr]

I always thought the spec was ≥.002 below flush.  But SAMMI says "... Properly seated, it should be flush or below the face of the [case] head."  Basically what I do is put a utility razor across the case head and hold it up to the light.  If you can see light between the primer and blade, it's good to go.

[Farmer]

I load all my test rounds with a hand primer and there are some that just plunk in the pocket, while others are a pretty firm press all the way. Those are the ones I double check and they usually need an extra squeeze. Even then they’re barely below flush. I’ve taken those tight ones to the uniformer and the pocket is usually tapered towards the bottom with the bottom edges more rounded than others. 

[stick]

Flush to just under sub flush.  Run your fingernail over the primer pocket.  if you can feel the primer, it's too high.

[RangerTrace]

14 hours ago, Sarge said:

I’ve also always thought the same thing. If I can’t feel a bump then it’s good? They always light using that standard for me. I wonder if a certain headstamp has deep pockets?

 Are you positive they are high? Or could it be light springs?

So I was having some light strikes with my #2 GGI pistol and sent the pistol back with 100 rounds of my match ammo.  If you look at my ammo in the hundo case gauge, the primers all appear to be properly seated.  However, as Bruce pointed out, some of my rounds will wobble when placed on a hard surface.  So, I put another 1/2 turn on my 1050 primer depth rod.  Bruce agrees with the .003-.004 depth.  Mine and my Gold dots are .001 according to my cheap calipers.  Keep in mind, I never had an issue with 1911s or even the first GGI pistol, so I thought I was okay.  

[zzt]

Bottomed.  Never any problems if bottomed.

[mmc45414]

36 minutes ago, zzt said:

Bottomed.  Never any problems if bottomed.

I was going to say, the cup might vary and the pocket might vary, so relative to the bottom of the case is just an approximation, but it is the approximation we all have always used.

In the OP's case, that was "not enough".. 

[m700]

Are these primers fully seated? It would be a pain to have to cut primer pockets to get yourself that distance.

Do these rounds go boom in your other guns? A stiffer spring may solve this.

 

I had a Shadow 2 that liked short rounds. I ended up selling it over getting barrel throated. I dont take s#!t from my guns  

 

The only issues ive had with primer height was a large handful of 223 had high primers(not fully seated) First attempt would seat them second would fire them. This was alot easier then pulling them.

[Fishbreath]

I jam them in until I see a dimple from the cup in the surface of the seated primer, but that's a revolver-specific 'optimization'.

[HesedTech]

17 hours ago, RangerTrace said:

but apparently flush with the bottom of the case isn't always deep enough.  

 

thoughts?

Depends on the primer manufacturer and depth of pocket. I have found Federal SP to be the tallest and Ginex the shortest. The point is if you can adjust seating depth, seat all primers as far as they will go and then a little bit more. To just seat them flush isn't deep enough for light hammer sprung guns.

[ysrracer]

How deep? All the way until it bottoms out.

[ysrracer]

12 hours ago, Fishbreath said:

I jam them in until I see a dimple from the cup in the surface of the seated primer, but that's a revolver-specific 'optimization'.

 

Yep, agreed

[MikeyScuba]

There is too much of a good thing in regards to Revo primer optimization 

[Farmer]

I know with the volume of rounds that most shoot that it would be prohibitive to uniform all the primer pockets. But I can tell you that when you seat a primer in a case that’s been done there is a Definite solid stop when it hits bottom. No springy, squishy feeling, it’s solid. Would be interesting to run a test between brass done and not done to see how light of a hammer spring could be used. Or if it would make any difference at all. 

[RangerTrace]

4 hours ago, Farmer said:

I know with the volume of rounds that most shoot that it would be prohibitive to uniform all the primer pockets. But I can tell you that when you seat a primer in a case that’s been done there is a Definite solid stop when it hits bottom. No springy, squishy feeling, it’s solid. Would be interesting to run a test between brass done and not done to see how light of a hammer spring could be used. Or if it would make any difference at all. 

The only time I can "feel" anything about the primer on my 1050 is if something went way wrong.  IE, a primer wasn't fully removed and I've smashed a new one on top of the old one.  I've added probably 3/4 of a turn to the primer seating rod, so I suspect I should be GTG now.

[HOGRIDER]

Started thinking, after reading this thread, of a reasonable/not too expensive way of checking the actual seated primer depth with some sort of accuracy other than using the tip of my slide micrometer.

 

A brief search came up with what I considered a reasonably priced "tool" that would work perfectly with my Starrett .125" dial indicator!  So I ordered one of F&FB's Primer Depth Fixtures; and it works PERFECTLY!  

 

https://fastandfriendlybrass.com/product/ffb-primer-pocket-depth-checking-fixture/

 

Since I haven't determined exactly where I want to mount it yet; I just chucked it up in the soft jaws of my vise and was pleasantly surprised with how easy and accurate it is to determine an exact primer depth!

 

For those loaders that need/want to have an accurate way of setting up your primer seating depth plus having an option to do a quick check; then I highly recommend trying one!

 

 

[4n2t0]

I use a high-tech low-cost tool, a table. Rounds with high primers will wobble when placed bullet to the sky on a hard flat surface.

Edited August 14, 2023 by 4n2t0

[IHAVEGAS]

On 7/19/2023 at 9:51 AM, Fishbreath said:

I jam them in until I see a dimple from the cup in the surface of the seated primer, but that's a revolver-specific 'optimization'.

It likely used to be revolver specific, but it also works well if you want to get your da/sa gun below 5 lb on the first shot and some of the striker gun trigger kits can use the help also so I am told. Anyway Dillon 1050, federal spp, I have adjusted depth to the point where I deform the primer on some range brass and on other mixed headstamp brass just drive it deep, for the wheel gun it is all the same brass so the dimple is consistent.