Primer fell out.

J

jetinteriorguy

New member
Doing some seat depth testing for my Savage 12FV in 6.5 Creedmoor and following Berger guidelines with Nosler RDF's in 140 grain I had a primer fall out after firing the second round. I had seated them deeper when doing the initial testing and had good results in two of the deeper depths so I was tweeking it by seating at smaller increments between these depths. The first round was fine, then the second round was missing the primer, which I later found rattling around in the magazine. In my initial test the only pressure signs were a slightly flattened primer but no cratering or imprinting on the base. This is on Starline LP brass that's been loaded a few times, not sure how many but possibly 4-5 times. So does this mean that piece of brass is shot due to the primer pocket being worn out, or do I have more serious problems. I've never had this happen before so I'm just trying to be cautious. Other than playing with the seating depth I've probably shot around a hundred rounds at this charge with no undue indications of over pressure even at a deeper depth.
 
Brass is toast . . . Head expansion creep finally donutted the hole. :mad:
Did you notice loose primer seating when loading? Or is this a one-time good deal ?
Also, has the flash hole expanded in that case when compared with other cases (or even new cases) ?

You don't specify the charge, but if a developing pattern, drop it a coupla percent for that
primer/powder/case/bullet/chamber/barrel combo
 
The primer seated with the usual felt resistance. I'll check the flash hole, thanks. The charge is 40.3 gr of H4350 giving an MV of 2745fps.
 
Running a QuickLoad comparison, it requires I adjust the Burn Rate up to match your velocity/24" barrel --> and pressures approaching 60ksi.

It's a 63ksi cartridge, so it still appears reasonable. But primer pockets tell the eventual tale of repeated stress even when immediate pressure signs are below threshhold.
 
I usually mark the case with a sharpie when ever I have a primer that seats a little easier than normal. You could try seating another primer in that particular case to see what the resistance is now after that event, might tell you something, or just trash the brass.

How is the accuracy with the FV12 in 6.5??
 
Doesn't matter what the computer says, your brass is telling you it was overloaded.

Rocky Gibbs said his wildcats should last ten loadings with snug primers.
One current gunzine writer says five is enough.

The first use I ever read for Loctite (1960s) was gluing in primers to get just one more load out of worn out brass. I know a present day shooter who does so.
 
I suspect that you have a pretty tight chamber that is pushing the pressure up over PMax.

I had a similar problem with large rifle primers with Norma and Hornady brass after about 4 loads with a Savage 12 LRP in 6.5mm Creedmoor.
Primer pockets on most of my brass wore out after 4 reloads.
But there were signs of high pressure on the head stamps as well even though I was loading well off PMax.

Hornady, who developed the 6.5mm Creedmoor cartridge, told me that many 6.5mm CMs are built with tight chambers to increase accuracy.

I experimented and found that even at minimum loads I was still getting high pressure indications. I took pictures of high medium and low pressure rounds and documented them and sent them to Savage.

They told me to send back the rifle and they reamed out the chamber a few thousandths and fixed the problem.
Turns out the cause was a tight chamber.
I recently loaded a batch of Lapua brass with small rifle primers 23 times until the primer pockets finally started to get loose enough to cause me to retire the lot. No primers have fallen out since the chamber was reamed out.
 
I had seated them deeper when doing the initial testing and had good results in two of the deeper depths so I was tweeking it by seating at smaller increments between these depths.
Click to expand...

I am not sure I am getting that part. I normally seat primers until they bottom out in the primer cup. My reasoning is what runs with what Dillon Precision and others mention on the subject of primer seating depth.

When primers are assembled, the anvil is not set into the priming compound. This is in order to make them safe to ship and handle. When you seat a primer, you are not just inserting it into the primer pocket. You are also "arming" the primer by forcing the anvil into the priming compound, so that the firing pin/striker impact reliably ignites it. The normal specs for seating a primer are for them to be at least .002" below flush, up to .009" below flush. Too high, and the primer may not go off-too much energy is absorbed in seating the primer deeper. Too deep, and it is possible to crack the priming compound, resulting in the primer not igniting at all.

If primers fail to go off after the initial strike, but go off after a subsequent strike, it is most likely that primers are not fully seated.

We have several helpful videos on our site. Just scroll down until you find the one you need.
Click to expand...

A close look at some CCI #200 Large Rifle primers makes the point as to the anvil not being set into the priming compound.

Anvil%20Position.png


The image is mine but if anyone wants it, have at it.

You can also measure your primers OD and the cup ID to get an idea if both are within specification and how tight your fit can be expected to be.

Ron
 
Oops, my bad. I’m referring to bullet seating depth testing not primer seating depth. Thanks for all the responses so far. Sounds like it may be time to start over and look for a node at a lower velocity. I’m going to go back to my test targets and see what they tell me.
 
Jetinteriorguy,

If I am reading in between the lines correctly, since you didn't state it explicitly, you are following the procedure Berger has in their Tech Talk area for making VLD's shoot better, and what you did was take a load that worked fine with some bullet jump to the lands and instead seated it to jam the lands to start that procedure. This will raise peak pressure, usually around 20%. In general, dropping the powder charge 10% will shave that 20% growth in pressure back off again. Either that or, as Berger does, you work the load up with the bullet jammed in the lands initially, and then start making the seating depth changes. After you establish the best seating depth, run through load workup again to fine tune it at that depth. You may even find you benefit from trying the retuned load at plus and at minus 0.01" just to make sure there isn't a slight change in best seating depth due to the changed pressure dynamics.

The idea is that the best general seating depth for a bullet design will be the same for all reasonable loads. I'm not sure this is always true, but a significant number of people get good results this way, so it is at least a tendency. Many have found that same optimum bullet jump turns out to best in their gun for all similar bullet ogive shapes.

Same powder charge; 0.030" bullet jump vs. touching the throat:
attachment.php
 
When primers start falling out it means the pressure has reached a point where you shouldn't go any higher.....Expanded Primer Pockets are a sign that you might want to back off that load. Too Hot . The head of the case is being enlarged .
Cases should wear out from neck or body splits or cracks ...the blown primer pockets should not be happening. By backing off a few grains your brass will last much longer.
Gary
 
No matter what the computer says the pressure should be, no matter what the pressure actually is, if the primer fall out of a case, THAT case has had too much pressure.

it could be just one "bad" case. It could be a "weak" batch of brass, or it could be that your load is just to HOT for that brass, no matter what the pressure numbers read, OR what the book or computer says . Every combination of components can be different, and sometimes, significantly so. And that also includes all factors of the gun and ammo fit, as well as the construction of the components themselves.

It is a science, but its not an exact science, and result are not necessarily linear. What worked for someone else ought to work for you, but ought to is not "will". Too many variables to give any kind of accurate diagnosis from a distance, other than if the primer falls out, the case head has swollen enough to allow that to happen.
 
Ok, I finally have some time so I'll try answer questions. Yes I'm following Bergers recommendation for determining optimal bullet seating depth with VLD type bullets. I decided to use the method they suggested for starting off the lands, not jammed .01 into he lands. I felt this would have a margin of safety and not surprise me with an over pressure situation. Started by loading six of each of the following, .050, .090, and .130. The best results were with .050 and .090. These were shot in two groups of three rounds each. And other than slightly flattened primers ther was no other signs of pressure, no primer cratering, no hard bolt lift, and no imprinting of either the ejector or extractor swipe. Then I proceed to load six each at .060, .070, and .080. This where the problem came in, at .080 the second round fired the primer was missing. At this point I shut it down and came here for help. I'm feeling like the next step is to either cut my load down and try some at the seating depths I've determined to be optimal, or just start over from scratch and redo the whole load.
 
This is what happens to pressure as bullet seating depth changes. The change is smaller than average and much more gradual in this plot than with pointed bullets because the bullet was round-nose, which has the most gradual taper from the bearing surface to the hemispherical nose. So this plot shape will be compressed to a shorter distance for the distance back from the ogive. Where seating deeper begins to raise pressure depends on case water capacity and load density of your charge. But, for all bullets there will be a seating depth below which pressure rises again. You may have found it for your load.

attachment.php
 
Thanks everyone for all the help. I'm going to take some time this weekend and review all my notes and targets from the beginning of my workup, and then determine where to go from here.
 
UncleNick, While knowing there was a Valley of Pressure Reduction, I'm amazed that lands clearance was able to offset the effects of reduced case volume -- that much --as the bullet was seated deeper -- to that extent. (1/4"...wow)

Any idea what cartridge was modeled?
 
If you read the fuzzy title, this was actual testing by Dr. Lloyd Brownell on 30-06 in his 1965 study. But it is, as I said, a round-nose bullet. Brownell suggested the mechanism of the pressure drop seating to longer bullet jump is the amount of gas bypass around the bullet that vents through the annular gap between the bullet and the freebore, stalling pressure build-up. When a bullet is jammed in the lands, there is none, raising pressure. With the round-nose design, the taper forward of the shoulder at the end of the bearing surface is so gradually that you have to seat it a lot deeper to get the same change in the area of the annular opening that a short distance produces with the pointed ogival shape. When you seat a pointed bullet deeper, that annular space rapidly gains area. This explains why in the plot in the earlier post #12, just 0.03" of greater seating depth makes as much difference as the 0.25" did with the RN bullet.

Of course, seating deeper always shrinks powder space and that increases pressure. You get the bottom of the trough in pressure where the dominant factor changes from gas bypass to reduction in powder space. With a pointed bullet, this will happen earlier in the increase of bullet jump.
 
40.3 grains of H4350 is .3 over Max according to Hodgdon. Differences in manuals accounts for it and it's not enough to blow out the primer. Their compressed 40.0 Max load ran 59,200 PSI at 2660 FPS with 2.820" OAL in their tests. So it's not exactly a light load and you need to look at your manual again.
And forget "seating depth" as a loading term. Load to the Max OAL given in your manual. SAAMI Max OAL is 2.825"(min is 2.700"). Both measured from the point bit of the bullet to the flat bit of the case with no ogives involved. Save you a lot of mucking about.
4-5 times loaded shouldn't be enough to expand the primer pocket either.
 
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