Primers seated too deep? Tulammo primers?

[GLOOB]

http://i688.photobucket.com/albums/vv241/gloob27x/TLS.jpg

Light strikes in a Glock 19. Gun was fully in battery and a second attempt was made after inspection and rechambering. These 2 failures occurred out of a batch of 70 or so.

On inspection, the primers are 0.011" deep. I still have the batch of primed brass that these loads came from. Measuring a small sample of them (all Win brass), I am measuring a primer depth of 0.006" to 0.010". I guess that's too deep!? I didn't even know you could seat a primer too deep?

I also have a some prepped cases using a CCI primer. I fished out a few Win brass from the lot and measured primer depth of 0.002 to 0.003".

The primers on the deep lot are Tulammo. I've loaded up only a few batches, and this is my first time firing them.

So whadya think? Should a Glock be able to light a primer that deep? Do I need to clean my Glock? Are Tulammo primers too short? Or am I crushing my primers in too hard (CCI seemed ok, and never a problem, before)?

BTW, these primers are noticeably pointier in their "dome" than CCI primers. But the dome has always flattened after I've seated them, CCI or Tulammo. Should a primer maintain its dome shape after seating?

 

[A-FIXER]

GL, Those are set really deep. How do the vary in length vs any other primer you have on stock? What method are you using to set and what is the make?

 

[GLOOB]

I measure a CCI primer at 1.065" tall, not including the anvil, of course. Tulammo at 1.08" tall. But the diameter of the Tulammo is measuring a fraction of a thousandth smaller. And like I said, it has a rounder cup. Apparently it can get smooshed shorter than the CCI when I seat it in my Lee SS press with my gorilla hands.

I'm already pondering the most expedient fix. I'm considering taking the primer arm and using a Dremel to concave the surface that pushes the primer cup. Maybe use some aggressive grinding compound on a rounded stick that's shaped like a primer dome, and spin it in the priming arm cup? That would reduce the maximum seating depth a hair and prevent the cups from flattening as much.

*Edit: Or maybe it's not the primers, at all. My friend commented my last batch of .357 primers had deep primers. I looked at them. They were pretty deep, and they were primed with CCI. At the time, I didn't think anything of it, because they all went bang. I just made a mental note that .357 seats deeper than luger, which is wrong, of course. Looking at my older 357 reloads, they are nearly flush. So either I've been eating too many Wheaties, or my press is wearing in (out?).

 

[LiveLife]

.010" is too deep. Primers should be seated about .004" below flush.

Once a year, I clean each of my Glocks down to individual components. One area many Glock owners miss is the bottom of the striker pin tube where hard caked on fouling builds up (area the other side of the breech face). When people have problem with light striker hits after firing a lot of rounds, I usually scrape up hard caked on black fouling at the bottom after a long soak in Hoppes #9 and using a small flat screwdriver. After the caked on fouling is removed, no more light striker hits.

The Rifleman's Journal posted an article that addressed the priming issue:

Primers: Seating Pressure and Pre-Compression

I recently received the following note from a friend overseas. Since the question and answer have broad applicability, I'll put them here for future reference. I'll try to take and post some pictures for this in the next week or so, but it wasn't really something I had planned and I'll have to scrounge up a camera with macro capability from a friend so it might take a while.

Hello German,
I have enjoyed reading a few of your posts and articles about primers among other things. I read a post recently were someone has been seating their primers way too hard and after some measurements, it seems my big clumsy fists have been squeezing the primers a bit too hard as well, giving about .008" crush at least. On the rare occassion I have been able to test over a chrono, I had higher than expected ES, so I am thinking it could have been the primers jammed in way too hard?

I mainly use the Russian SRM and LR primers in my 6x47 Lapua and my .284. What sort of crush should we be looking for with these primers?

Thanks for any help, from Rod D.


Hello Rod,
Primers have a definite "sweet spot" in terms of seating pressure and pre-compression of the pellet. These days the manufacturers give out essentially no technical information on the properties of their primers, we're all taken to be semi-useful fools, I suppose. However, at one time, Federal used to recommend a "light pre-compression" now that's a pretty vague statement, but better than silence.

Creighton Audette tried to get some numbers from Federal and got nothing more from them. He then designed what is now sold as the K&M seating tool that allows you to measure how much pre-compression (crush) you are applying to the primer (K&M also makes a version without the gauge). Of course, the system depends on all primer pockets being uniformed for depth. After a great deal of experimentation with pre-compression and related accuracy testing, Creighton determined that there was no specific number, but you could definitely do too much or too little. Very ironic, a light pre-compression indeed turned out to be best... whatever that means. No one was better at this sort of testing than Creighton, by the way. I'm as chagrined at the non-numberical result as he was but not knocking his work in any way.

I use the Sinclair tool which is another version of the Audette design, although without the crush measuring ability. Both the Sinclair and the K&M give the best feel for what's happening as the primer seats of all the tools I've tried.

In my own testing, I have found that the best method is to clean the primer pocket (I don't uniform them) then, seat the primer until you feel it just touch, then apply a bit more pressure (not a lot) until you feel a second level of resistance just starting.

Photo from the Remington website shows how the anvil will pre-compress the pellet on seating (see article link for photo).

If you examine some new primers you'll see that the legs of the anvil stick out past the bottom of the cup. When the legs hit the bottom of the primer pocket you feel that first resistance. As you continue to apply pressure you bring the cup over the legs and then the second level of resistance begins as the center of the anvil begins to compress the pellet. Stop!

The primer pellet is very small, it typically weighs 0.5 gr. for a large rifle primer and it can be cracked through the application of too much seating pressure. However, it needs a tiny bit of pressure as the tip of the anvil should be in contact with it when the firing pin hits - it shouldn't have to move at the firing pin's impact to make contact with the anvil. If it has to move, or if it has been cracked, SD will increase.

To continue a bit with the unfortunately non-numerical approach, if the primer loses its edge radius on seating and looks somewhat concave, that's way too much pressure. A bit of flattening is normal and correct, but like Goldilocks testing the bears' mattresses, there's too soft, too firm and just right.

A worthwhile test might be to try chronographing three sets of loads, one in which you stop as soon as you get initial resistance (legs at the pocket bottom) one where you crush mightily, and one where you add a slight pre-compression as described above. The Goldilocks test so to speak. I would be very interested to hear your results and will do the same test myself next time I chronograph something.

Primer on primer that's posted on Co-Ax website that I have used in the past to illustrate the proper seating depth of primers.

Crushed primer - The top drawing shows a primer that is seated all the way to the bottom with the anvil deeply cutting into the priming compound. The primer cup is flattened.

High primer - The middle drawing shows a primer that is seated too high and the primer cup has not been pushed enough into the primer pocket. Such high primer is the usual cause of misfires that will fire on the second strike as the first strike will push the primer cup further down only, which then sets the anvil to fire on the second strike.

Slightly below flush - The bottom drawing shows a properly seated primer that has the anvil against the priming compound and the top of the primer cup is below flush. Primer cup top is still rounded.

A Primer On Primer Seating

The following three drawings illustrate the critical nature of accurate primer seating.

Primer SeatingIllus. 1: IMPROPERLY SEATED - This primer is improperly seated, preventing the cups of the primers from resting solidly on the bottom of the primer. Some primer cups measure .120” in height, and if seated with crowns more than .004” below the case head, the anvil would be forced through the crown, rendering the primer useless.

Illus. 2: IMPROPERLY SEATED - This primer is improperly seated too high. A high primer is erratic in performance. It is also dangerous and could explode in the chamber of a rifle when the breech block closes on it before it is locked.

Illus. 3: PROPERLY SEATED - This primer is properly seated, exactly as it would be with our Co-Ax® Reloading Press. The crown is .004” below the surface of the case head; the anvils are on the bottom of the primer well; and the primer mix is properly stressed by the anvil for sensitivity. It is also much safer than either of the two seated primers shown above.

 

[billybob44]

Deep Primers?

The case on the right really has the primer too deep. I would mic the primer thickness as well as the primer pocket of the W-W cases.

BTW, have you installed an aftermarket fireing pin in your Glock? The primers don't show the usual "&" mark from a factory pin.
Those pin marks look like from my CZ-75's. They usually are very small in dia. and not real deep=just like your cases.
If that IS a aftermarket fireing pin in your Glock, you may need to go back to the factory pin to set off these loads??..Bill..

 

[A-FIXER]

Good post bds, That should help GL alot... and I also read you shooting lead in your glock and all I can say is pineapple mush is good.

 

[Robert Palermo /Penn Bullets]

BDS is quite correct.
I am wondering if theres a severe variation in the height of the primer cups and or if the anvil is missing from those primers in those cases. I have never seen that before with domestic primers. Usually primers that are seated that deep are crushed but these don't appear to be crushed.

 

[billybob44]

BDS is quite correct.
I am wondering if theres a severe variation in the height of the primer cups and or if the anvil is missing from those primers in those cases. I have never seen that before with domestic primers. Usually primers that are seated that deep are crushed but these don't appear to be crushed.

Bob, you don't think them Russkies would have shorted the OP the anvil on those primers do you?? HA HA..Bill..

 

[LiveLife]

The seated primers in the photo definitely look like "crushed" primer cups.

Properly seated primers should retain the "rounded" cup.

 

[GLOOB]

Oh, yes. Definitely. Crushed. Yep. I added an edit to my second post, when I realized I was seating too deep with CCI primers, too. But the Tulammo SPPs were especially squishy. They're definitely softer than CCI SPPs. So it would appear these light strikes were due to user error. Good info, bds. Thanks.

BTW, have you installed an aftermarket fireing pin in your Glock? The primers don't show the usual "&" mark from a factory pin.

Nope. the primer is so deep that the pin barely touched it. That's why it looks round!

all I can say is pineapple mush is good.

Yessiree, it is. I didn't even realize it was pineapple season. I've always wanted to bag a pineapple, but the price always threw me off. When I saw the tag , I immediately put back 5 of my watermelons and proceeded to buy a couple armloads. While I was doing so, I heard another chap remarking on the incredible price, and I had to wonder if he was a shooter, too!

... and now I suddenly feel the urge to donate to a hunger relief organization...