9 mm primer seating depth

[Nordeste]

I have noticed it varies from one headstamp to the other. On Remington brass I get the worst results, with the primers being seated at .003"-.004". CBC Magtech, Geco and Sellier&Bellot stay within the .005" to .007" and my favorite brass to work with, Fiocchi, stays at .007 to .010", also producing the more consistent OAL of the whole bunch.

Don't get me wrong. The ammo I've loaded using Remington brass worked and works well. I had a couple of primers that didn't go bang on the first stroke in the past, but that could well have been me not priming hard enough. They did go bang on the second strike. It's just that I feel more confidence when I see the primer seating clearly under the bottom of the cartridge.

Have you bothered measuring your primer seating depth?. What do you think of the number I got?.

PS: I use a Lee Classic Turret

 

[Slamfire]

I am of the opinion that 0.003" is about right. The deeper the primer the more likely the firing pin won't be long enough to give is a hard hit.

It is a safety issue to ensure that the primer is below the case head. Nothing but the firing pin should hit a primer, and if the primer pocket is shallow, and the primer anvil seated on the bottom and the primer cake is pushed into the anvil, that primer is ready to ignite if struck. CCI says these are the conditions necessary to get a primer to ignite, they also say the most common cause of misfires are high primers where the anvil is dangling in the air. Which explains the double strikes it took to ignite your misfires. The first hit seated the primer. This is not a reliable mechanism as the primer cake can break on the first strike and all you will get on the second hit is a dud.

Given that the primer needs to be below the case head, as long as they are below the case head and not seated too deep, you will have reliable ignition.

 

[tightgroup tiger]

^^^^^

.003-.005"below flush is about as good as it gets. Seating any deeper could cause damage to the primer pellet.

What Slamfire said.

 

[gamestalker]

I don't measure my primer depth, per say. I have measured in the past, but just out of curiosity, as to how deep I'm seating them. That was a long time ago though, so I honestly don't recall what I came up with. I think my Speer # 10 says something like .004" - .010", depending on primer pocket depth.

As for how deep they need to be seated to eliminate mis-fires, that is something I decide when I thread my priming die into my SS press. And then, as I begin seating, if I feel one that doesn't quite feel like it was all the way home, I then give the die another small adjustment down. For me, the determine that it's completely seated when I can feel it. For lack of a better word, you can feel it pre-load, a slight rebound. It's worked great for me for several decades of reloading, as I've yet to experience a single mis fire.

GS

 

[ArchAngelCD]

I am of the opinion that 0.003" is about right. The deeper the primer the more likely the firing pin won't be long enough to give is a hard hit.

It is a safety issue to ensure that the primer is below the case head. Nothing but the firing pin should hit a primer, and if the primer pocket is shallow, and the primer anvil seated on the bottom and the primer cake is pushed into the anvil, that primer is ready to ignite if struck. CCI says these are the conditions necessary to get a primer to ignite, they also say the most common cause of misfires are high primers where the anvil is dangling in the air. Which explains the double strikes it took to ignite your misfires. The first hit seated the primer. This is not a reliable mechanism as the primer cake can break on the first strike and all you will get on the second hit is a dud.

Given that the primer needs to be below the case head, as long as they are below the case head and not seated too deep, you will have reliable ignition.

Not much to add there. Sounds right to me...

BTW, I have never actually measured the depth of a primer, I rub my finger over the primer and it it's just below the case bottom it's good to go...

 

[murf]

measure the depth of a factory round.

you can also shoot a few factory rounds through your gun to see if the gun is the problem rather than your seating method.

murf

 

[gamestalker]

^^^

 

[jwrowland77]

Nope never measured primer depth. Just loaded them and shot them. I do run my finger over the primer to make sure it's below flush but that's it

 

[45lcshooter]

^^^^^^ all I've done is make sure the primer is in above the bottom of the case. You may want to ream your cases or get a Lee Auto Prime and prime by hand.

 

[beatledog7]

I check primer depth by standing a primed round on a known flat surface. If the case wobbles at all, the primer is not deep enough. If the case doesn't wobble, the primer is deep enough.

Hand priming is my only priming method, and that's because hand priming makes it easy to get a feel for when a primer is fully seated. Seat a couple in a batch, test for wobble, observe no wobble, continue, making sure to get that same "feel" every time.

I've never had any kind of malfunction with a handloaded round.

 

[Reloadron]

Do I actually measure the seated depth? No, I just give them a looking over. I might measure the first several in a batch but that is about it, assuming the same brass and primers.

I hand prime using either a Lee or RCBS hand priming tool. I like the hand priming method because I can get a good feel for when the primer bottoms out in the case cup.

I like to see my primers seated to a depth around .003" to .005" below the case head but this can be a frustrating aspect of hand loading. You can't always get what you want as the saying (and Stone's song) goes.

The primer pocket specifications for both small pistol and small rifle are the same and by SAAMI specifications are for depth .1170" to .1230". The middle of the range being .120". So a case primer pocket having a depth between .117" and .123" would be, according to SAAMI specifications, a primer pocket within specification. Case primer pocket depth will vary from manufacturer to manufacturer and even lot number within a manufacturer.

The actual primers themselves also have specifications and limits. Primer height minimum is .1150" and maximum is .125". Those are the SAAMI specifications for small pistol (and small rifle) primers. Now it doesn't take much to see these specifications can lead to some problems as they do overlap.

I have some Winchester Small Pistol primers sitting here and their height is .1160" so they exceed the minimum by .0010". I also have some CCI small pistol primers and they measure .1200" so they are also within SAAMI specifications and the CCI height exceeds the Winchester height by .004".

I have some factory new Starline .38 Spl. brass sitting here. The primer pocket depth measures .1200". Now it stands to reason that if I prime these cases using the CCI primers I mentioned above I'll be hard pressed to get much depth below the case head. However, if I use the Winchester primers mentioned with a height of .1160 I should have no problems getting a seated primer depth about .004" below the case head. If I were to load these cases up I would likely prime with the Winchester primers if I wanted some depth in there after priming.

The end result will always be a function of the brass and primer manufacture.

The same is true for primer width as to the numbers. Only different numbers.

Just My Take....
Ron

 

[floydster]

After loading for over 60 years, seat them till they don't go any farther, period--and this talk about primer depth is---well--bull.
Smokeyloads

 

[Walkalong]

BTW, I have never actually measured the depth of a primer, I rub my finger over the primer and it it's just below the case bottom it's good to go...

Me too, never measured it until curious folks here asked. We were always taught to seat primers fully against the bottom of the primer pocket. Then use a finger or thumb to make sure they are below flush. And, IMO, harder is better than softer. I seat 9mm primers fairly stiffly, in all sorts of brands of brass, and never have misfires. I used to seat 6 PPC primers for Benchrest loads with the utmost care trying to get them all just perfect, but one evening Allen Hall was talking shooting and said, if the primer goes bang, you don't have a problem. I still tried to seat my 6 PPC primers carefully, but never agonized over it again. I still try to be consistent with seating rifle primers, but I don't have any anxiety about it either.

 

[Steve C]

Measuring primer depth is pointless and tells you nothing. The only depth requirements are they must be at or below flush with the bottom of the case AND most importantly, seated to the bottom of the pocket, whatever that depth happens to be. This is most easily done by feel.