Tight Primer Pockets

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  • Last Post 21 June 2024
Wm Cook posted this 20 June 2024

What can cause primer pockets to tighten up? 

I have some LR.308 Lapua cases that came in new at about 2.008".  After neck turning and fire forming they shortened to about 2.004 and they'e stayed there with no changes.  Loads are relatively mild with 200 to 220 grain 30cal running 1630 to 1730.   I'm only neck sizing so the sholders have never been bumped.  That said the bolt closes easy.  The bottom of the pockets are cleaned with a Lyman tool pocket cleaner.  . 

I separated out 10 of these cases to shoot 10 shot strings for some testing I had going on.  From my notes I've got 16 firing on each case.  Primers have been Fed 210 throughout.  The last couple times I noticed the primer pockets starting to tighten up.  As of today they are caput.  I've never had this happen to me before so any help would be appreciated.  Thanks, Bill.  

 

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muley posted this 20 June 2024

I had some similar trouble with Fed 205M and found they were in a bad batch. the other cartons were no trouble. maybe same problem ???

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RicinYakima posted this 20 June 2024

My understanding is that as the case head slowly expands, due to repeated pressure, the outside moves to meet the chamber wall. However, the primer cavity gets smaller and the metal moves to vacant/weak  space of the primer cup. FWIW

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trapdoor4570 posted this 20 June 2024

Perhaps a test with a primer pocket swager might be interesting?

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pat i posted this 20 June 2024

If you have any Winchester primers try those.

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mhice posted this 20 June 2024

 As long as you do not have a threat of case head separation, a primer pocket swager will push the brass back so you will have normal primer seating feel. If the .200" line measurement is grossly oversized or you have indication of case head separation, trash the brass.

Lapua is great brass, but you have to use your noodle. That being said, I have some .220 Russian Lapua brass that has been made to 6 PPC that has over 30 firings. Might lose them tomorrow but I got my money's worth.

-Michael

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RicinYakima posted this 20 June 2024

Lupua is the Packard of brass cases. 

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Wm Cook posted this 20 June 2024

I've never had to use a swagging tool before.  Can anyone recommend which one to use? 

Its odd that I've been handloading for so long and this is the first time I've seen it.  I believe the loads to be low pressure.  Heavy bullets for caliber yes, but I'm only pushing them around 1700fps.  With high pressure loads pockets always opened up for me not shrink down.  In normal jacketed full boat loads you see the powder wave  pattern around the case neck.  All of my cases show powder but no wave pattern.  Its a factory barrel with ~ a .3488 neck and the loaded round is ~ .3382 so the case neck isn't sealing to the neck wall.  I've got some Winchester primers but the problem is going to require a tool that's not on my bench.  Guess I can find a you tube video to see how to go about using it.. 

Just bothers me that I don't know why the pockets shrunk.  I've shot a lot of hot loads with jacketed and know how pockets open up.  Never saw them tighten up.  If you can stuff enough powder into a PPC case you'll loose primers quick enough.

Agreed Rick, Lapua's good brass.  Bill.

 

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trapdoor4570 posted this 20 June 2024

I use the Dillon, it was designed for just one job.  Have several that screw into the press but love the Dillon.  Can process 100  '06 or 7.62 NATO quickly and it does a beautiful job.  Also when I have used the Federal primers sometimes they are a tight fit.  Do you have a dial caliper, curious as to what the pocked diameter is?  Have never see a pocket get tighter but have seen many blown primers that just fall out.  Have been reloading for almost 60 years.  Am still learning things every time I load or shoot.

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Wm Cook posted this 20 June 2024

 I'll measure it in the AM James.  I might have an original new piece of brass from that batch and I'll look at the case head dimension's as well.  Do you think a swagge will open the pocket without crushing? I think the lip on the swagger rod has a taper on the tip doesn't it?

Again, confused as heck.  Started to notice that things were going wrong when my Wilson neck sizer pin was having trouble punching out the spent primer.  Then I came accross a couple primers that stood out proud from the base.  Then within a few shots it was obvious that the pocket was squeezing shut.  

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Aaron posted this 20 June 2024

Dillon swage tool is the best.

Like mentioned above, try different primers too. For years CCI primers were the worst for me, now they seem to seat as easily as Winchester primers do. Batch size variation may be affecting you too. As you know, a .0005" measurement in a firearm, ammunition, or primer, is like the Grand Canyon to a firearm.

The Dillon tool is well worth the money, especially for 223 (oops..... 5.56) military brass. I can't afford new brass for every ammo reload run and have to recycle scrounged brass. When I win the Mega Super Humongous Lotto, I can then purchase new brass as needed. smile

 

With rifle in hand, I confidently go forth into the darkness.

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Wm Cook posted this 20 June 2024

From the looks of things it was damage to the primer pocket opening rather than a tightened primer pocket.  On unfired versus the problem brass the primer pockets were the same at ~ .205 (Veener caliper) and case head was identical at .2488.  I used my chaffering tool and cleaned up the top of the pocket and the primer slid in like normal. At least on a quick check this AM thats the way it looks.

My current theory is that the pocket opening was damaged from the misalignment of the primer to the pocket while seating.  Both my hand primers are pushing 30 years old and I just got complacent in their condition.  I'll let you know if its anything other than that.  Thanks for the help, Bill.

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Scota4570 posted this 21 June 2024

Be careful with the Dillon tool.  I ruined a gallon bag of 223 brass with one, I should have checked early on in the batch.

The mandrill was made to large.  When I called them Dillon was not helpful or concerned.  I ended up modifying the mandrill  to properly remove the crimp, chamfer the edge  and not wallow out the primer pocket.  

Mostly I run a Lyman style cutter in a lathe collet.  IT works faster and does the same job.  Wear a glove.  I once had a 30-06 case with a sharp edge case mouth cut a circle out of my hand.   Don't do that!

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