First run-in with loose primer pocket

[Short-bus]

Had my first ever run-in with a loose primer pocket this evening. I did notice that the primer seated exceptionally easy when priming my brass (was only loading 12 rounds to zero with tomorrow), but didn't really think anything of it as I have several other rounds that the primers seat easily, but not THAT easily.

Poured my powder charges in all the cases, and when I went to seat the bullet in this particular case, I heard a little pop, and across the floor went the primer. I pulled the bullet, dumped the powder, and have used a sharpie to mark the case as no longer usable.

This sucks, that means that I have to get a new box of brass soon. Only got about 8 reloads from this set of Lapua. I suppose my 208's are running a bit hot for it. Probly getting a little case head expansion.

Branden

 

[Downzero]

Re: First run-in with loose primer pocket

I wouldn't mark it with a marker, I'd squeeze it closed with pliers and throw it in the trash. 8 loadings sounds great to me! 9 cents a shot or so? That's not too bad at all, especially if you're using a stiff load.

 

[desertHK]

Re: First run-in with loose primer pocket

8 loads with Lapua brass is a bit "pre-mature". I have stopped counting after 15 times with my Lapua 308 brass. BTW, my load is relatively hot. 47.4 grains of Varget driving the 155 scenars.

 

[Short-bus]

Re: First run-in with loose primer pocket

I've been FL sizing everytime. I did some neck sizing for one load, but I found the accuracy of FL sized to be better, and my SD's were lower by about 30%. Weird.

Branden

 

[Country]

Re: First run-in with loose primer pocket

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dust_Remover</div><div class="ubbcode-body">I've been FL sizing everytime. I did some neck sizing for one load, but I found the accuracy of FL sized to be better, and my SD's were lower by about 30%. Weird.

Branden </div></div>
Thats part of your problem , your are oversizing your brass but if you are running an auto then extra sizing is usually required.
If you are running a bolt gun then I would try and only neck size untill the cases get a bit sticky then FL size.
Another way to increase case life is to use a body die inplace of the Normal FL die . That way you can have better control over how much you size and how much you bump the shoulder if required.
If you definately get better accuracy from FL sized brass then that could indicate a slightly crooked chamber.
A normal straight chamber should shoot better with fireformed cases and minimul sizing.

 

[Victor N TN]

Re: First run-in with loose primer pocket

If you want to save the brass, get an RCBS primer pocket swage die kit. One kit does both large and small primer pockets, both rifle and pistol. It will tighten up the pockets as well as swage out the military crimp.

 

[esorensen]

Re: First run-in with loose primer pocket

Hmmmmm... Maybe I'd better get all the culled brass back out of the recycle bucket after all.

 

[Short-bus]

Re: First run-in with loose primer pocket

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Country</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dust_Remover</div><div class="ubbcode-body">I've been FL sizing everytime. I did some neck sizing for one load, but I found the accuracy of FL sized to be better, and my SD's were lower by about 30%. Weird.

Branden </div></div>
Thats part of your problem , your are oversizing your brass but if you are running an auto then extra sizing is usually required.
If you are running a bolt gun then I would try and only neck size untill the cases get a bit sticky then FL size.
Another way to increase case life is to use a body die inplace of the Normal FL die . That way you can have better control over how much you size and how much you bump the shoulder if required.
If you definately get better accuracy from FL sized brass then that could indicate a slightly crooked chamber.
A normal straight chamber should shoot better with fireformed cases and minimul sizing. </div></div>

Oh if only I had the money for a new set of bushing dies and some other goodies. This lovely economy has caused cut backs at work, granted we're still financially just fine because we live well within our means, with Christmas approaching, i'm saving what there is for my little girls presents. I'm not so selfish that I would treat myself over my cut little daughters. Last thing I need is for them to become strippers because daddy bought a new set of reloading dies rather than the latest barbie doll that they "will die if they don't get it".

Branden

 

[BallCoeff_606]

Re: First run-in with loose primer pocket

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dust_Remover</div><div class="ubbcode-body">Had my first ever run-in with a loose primer pocket this evening. ... I suppose my 208's are running a bit hot for it. Probly getting a little case head expansion.

Branden </div></div>

Probably case head expansion. I found I can go years on reloading the same set of casings until getting too ambitious with powder loads. Then primers start to fall out and everything starts sticking. That usually won't happen unless you start pushing the pressure envelope for one reason or another.

I've always done full-length resizing, because that's how my progressive is set up.

 

[Clark]

Re: First run-in with loose primer pocket

LC 308 brass necked down to .243, three identical hot rounds fired in a row.

I have had the primer pockets get loose in 243, 25acp, 19B, 7.62x25mm, 7.62x39mm, 257Roberts Ackley improved, 10mm, 223, 308, 30-06, 8x57mm, 9x19mm, 357 Sig, 45acp, and 7mmRemMag.

Two different guys on the internet have done analysis on the weak spot of brass cases with extractor grooves; Varmint Al and Assclown.

The 1889 7.65x53 Mauser case head design, when made with a large Boxer primer is good for about 65,000 psi in personal handloads for one rifle and 62,000 psi for commercial ammunition.
I am guessing that is why the newer 260Rem was registered with SAAMI at 62kpsi, and not 65kpsi like the older 270Win.
Although registered at a lower pressure, the 223 can take much more pressure before the primer pocket grows.
The 6mmBR is not registered, and can take even more pressure than the 223. The 6mmBR limitation is the primer piercing, not the primer pocket growing. The 6mmBR has a small primer pocket with lots of brass around it, and so is stronger.

What I do is measure the extractor groove growth all the way around. The first growth may be asymmetrical.

Depth min max diameter min max
small rifle primer pocket .117 .123 .1730 .1745
small pistol primer pocket .117 .123 .1730 .1745
Large rifle primer pocket .125 .132 .2085 <span style="color: #FF0000">.2100</span>
Large pistol primer pocket .117 .123 .2085 .2100


Height min max Diameter min max
Small rifle primers .115 .125 .1745 .1765
small pistol primers .115 .125 .1745 .1765
large rifle primers .123 .133 .2105 .2130
large pistol primers .115 .125 .2100 .2120"

Measuring the primer pocket with pin gauges is problematic.
Someone has suggested "D" pin gauges, but I don't have any.
So I use dial calipers and measure the extractor groove. At the first sign of expansion, I back off on the load a safety margin. Vernon Speer said that should be -6% powder change in 1956.

Right now I am running -4% in my 7mmRemMag. I will see if I get away with it.

 

[Short-bus]

Re: First run-in with loose primer pocket

Great info Clark, thank you.

As for my loads, I think I could back off a bit, i'll do some more load development. I only wanted 2500fps from the 208's, and i'm pushing 2600, so there's room to move back. I just hope that the accuracy node is wide enough to allow me to back off, and not lose the great groups i'm getting.

Branden

 

[Victor N TN]

Re: First run-in with loose primer pocket

Having standard tools I would say that a small hole guage (telescope) and 0-1" mic with tenth venier would be the closest. But I'm not going to tah much trouble right now. I just seperate them if I get a loose pocket. When I have enough for a batch I use the primer pocket swage tool from RCBS I mentioned above. But if it looks hairy or different in any way, it goes in the scrap box under the bench.

 

[Country]

Re: First run-in with loose primer pocket

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dust_Remover</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Country</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dust_Remover</div><div class="ubbcode-body">I've been FL sizing everytime. I did some neck sizing for one load, but I found the accuracy of FL sized to be better, and my SD's were lower by about 30%. Weird.

Branden </div></div>
Thats part of your problem , your are oversizing your brass but if you are running an auto then extra sizing is usually required.
If you are running a bolt gun then I would try and only neck size untill the cases get a bit sticky then FL size.
Another way to increase case life is to use a body die inplace of the Normal FL die . That way you can have better control over how much you size and how much you bump the shoulder if required.
If you definately get better accuracy from FL sized brass then that could indicate a slightly crooked chamber.
A normal straight chamber should shoot better with fireformed cases and minimul sizing. </div></div>

Oh if only I had the money for a new set of bushing dies and some other goodies. This lovely economy has caused cut backs at work, granted we're still financially just fine because we live well within our means, with Christmas approaching, i'm saving what there is for my little girls presents. I'm not so selfish that I would treat myself over my cut little daughters. Last thing I need is for them to become strippers because daddy bought a new set of reloading dies rather than the latest barbie doll that they "will die if they don't get it".

Branden </div></div>
Mate when I was young and in your position I made my own body dies by cutting the tops off standard FL dies . That was way before Redding or anyone else brought them out for sale.
If you know someone with a lathe you can just turn the top off the die and drill the neck area out just larger than the loaded brass and you have a body die.
As for your loads I agree you should back off a bit before it backs you off.

 

[Short-bus]

Re: First run-in with loose primer pocket

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Country</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dust_Remover</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Country</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dust_Remover</div><div class="ubbcode-body">I've been FL sizing everytime. I did some neck sizing for one load, but I found the accuracy of FL sized to be better, and my SD's were lower by about 30%. Weird.

Branden </div></div>
Thats part of your problem , your are oversizing your brass but if you are running an auto then extra sizing is usually required.
If you are running a bolt gun then I would try and only neck size untill the cases get a bit sticky then FL size.
Another way to increase case life is to use a body die inplace of the Normal FL die . That way you can have better control over how much you size and how much you bump the shoulder if required.
If you definately get better accuracy from FL sized brass then that could indicate a slightly crooked chamber.
A normal straight chamber should shoot better with fireformed cases and minimul sizing. </div></div>

Oh if only I had the money for a new set of bushing dies and some other goodies. This lovely economy has caused cut backs at work, granted we're still financially just fine because we live well within our means, with Christmas approaching, i'm saving what there is for my little girls presents. I'm not so selfish that I would treat myself over my cut little daughters. Last thing I need is for them to become strippers because daddy bought a new set of reloading dies rather than the latest barbie doll that they "will die if they don't get it".

Branden </div></div>
Mate when I was young and in your position I made my own body dies by cutting the tops off standard FL dies . That was way before Redding or anyone else brought them out for sale.
If you know someone with a lathe you can just turn the top off the die and drill the neck area out just larger than the loaded brass and you have a body die.
As for your loads I agree you should back off a bit before it backs you off. </div></div>

Only reason that i'm not wanting to back off is that I have no other pressure signs. No flat primers, no difficult bolt extraction, back when it was a lot warmer out, I would get some very light ejector marks, however now that it's cooled down that's not occuring. I'm getting great accuracy from the load. Once deer season is over, i'll get back to testing loads out. I have to go and check my target archives for this load, but I believe that .3gr under my current load still shot fairly well, however if I remember off the top of my head correctly, I chose this load because the SD data from the chrono was the best of all the loads I tried.

Branden

 

[Country]

Re: First run-in with loose primer pocket

From the photos you posted and thats all I have to go on , you do have flattened and cratered primers and the fact that some extracion difficulties show up in warm weather indicates to me you are on the edge of dangerous pressures .
What velocities you are getting is irrelevant to safe chamber pressures.
Is the case an Ackley improved or other improved design ?
If it is that could explain why you are not having extraction problems and the primers are not as flat as they might otherwise be.
The bolt rear thrust is reduced in an Ackley improved design. However they can go from safe pressure to KA-- BOOM!! real quick

 

[Short-bus]

Re: First run-in with loose primer pocket

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Country</div><div class="ubbcode-body"> From the photos you posted and thats all I have to go on , you do have flattened and cratered primers and the fact that some extracion difficulties show up in warm weather indicates to me you are on the edge of dangerous pressures .
What velocities you are getting is irrelevant to safe chamber pressures.
Is the case an Ackley improved or other improved design ?
If it is that could explain why you are not having extraction problems and the primers are not as flat as they might otherwise be.
The bolt rear thrust is reduced in an Ackley improved design. However they can go from safe pressure to KA-- BOOM!! real quick </div></div>

I've never posted photos of my brass, so I don't know where you get that idea from unless you are responding to another poster. I've not had extraction issues, only once or twice i've had a stiffer bolt lift than usual, but that was back when it was almost 100 degrees out. I know i'm likely at the edge of the limit with these loads when it's hot out, but now that the temperature has come down, it's not so much.

The case is no wildcat, just the standard .308 case. I'm going to back off the load during the warmer months, but it's not a problem with the weather being much cooler right now.

I need to find somebody around here to shoot with that has a strain gauge that can be affixed to my rifle to test the pressure. That would be really cool!

Branden

 

[Country]

Re: First run-in with loose primer pocket

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dust_Remover</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Country</div><div class="ubbcode-body"> From the photos you posted and thats all I have to go on , you do have flattened and cratered primers and the fact that some extracion difficulties show up in warm weather indicates to me you are on the edge of dangerous pressures .
What velocities you are getting is irrelevant to safe chamber pressures.
Is the case an Ackley improved or other improved design ?
If it is that could explain why you are not having extraction problems and the primers are not as flat as they might otherwise be.
The bolt rear thrust is reduced in an Ackley improved design. However they can go from safe pressure to KA-- BOOM!! real quick </div></div>

I've never posted photos of my brass, so I don't know where you get that idea from unless you are responding to another poster. I've not had extraction issues, only once or twice i've had a stiffer bolt lift than usual, but that was back when it was almost 100 degrees out. I know i'm likely at the edge of the limit with these loads when it's hot out, but now that the temperature has come down, it's not so much.

The case is no wildcat, just the standard .308 case. I'm going to back off the load during the warmer months, but it's not a problem with the weather being much cooler right now.

I need to find somebody around here to shoot with that has a strain gauge that can be affixed to my rifle to test the pressure. That would be really cool!

Branden </div></div>
Sorry Dustremover you are right . It was Clark that posted the brass pictures . I thought that was your brass .
I take back what I said in reference to those photos.
It was an honest mistake. No disrespect was intended.

 

[MitchAlsup]

Re: First run-in with loose primer pocket

I shoot some loads that are on the edge of sane pressure, however, I am getting over 25 reload cycles on Winchester brass. Having cases with blown primer pockets at 8 cycles with Lapua brass is unusefully hotter than my loadings.

 

[Short-bus]

Re: First run-in with loose primer pocket

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Clark</div><div class="ubbcode-body">

LC 308 brass necked down to .243, three identical hot rounds fired in a row.

I have had the primer pockets get loose in 243, 25acp, 19B, 7.62x25mm, 7.62x39mm, 257Roberts Ackley improved, 10mm, 223, 308, 30-06, 8x57mm, 9x19mm, 357 Sig, 45acp, and 7mmRemMag.

Two different guys on the internet have done analysis on the weak spot of brass cases with extractor grooves; Varmint Al and Assclown.

The 1889 7.65x53 Mauser case head design, when made with a large Boxer primer is good for about 65,000 psi in personal handloads for one rifle and 62,000 psi for commercial ammunition.
I am guessing that is why the newer 260Rem was registered with SAAMI at 62kpsi, and not 65kpsi like the older 270Win.
Although registered at a lower pressure, the 223 can take much more pressure before the primer pocket grows.
The 6mmBR is not registered, and can take even more pressure than the 223. The 6mmBR limitation is the primer piercing, not the primer pocket growing. The 6mmBR has a small primer pocket with lots of brass around it, and so is stronger.

What I do is measure the extractor groove growth all the way around. The first growth may be asymmetrical.

Depth min max diameter min max
small rifle primer pocket .117 .123 .1730 .1745
small pistol primer pocket .117 .123 .1730 .1745
Large rifle primer pocket .125 .132 .2085 <span style="color: #FF0000">.2100</span>
Large pistol primer pocket .117 .123 .2085 .2100


Height min max Diameter min max
Small rifle primers .115 .125 .1745 .1765
small pistol primers .115 .125 .1745 .1765
large rifle primers .123 .133 .2105 .2130
large pistol primers .115 .125 .2100 .2120"

Measuring the primer pocket with pin gauges is problematic.
Someone has suggested "D" pin gauges, but I don't have any.
So I use dial calipers and measure the extractor groove. At the first sign of expansion, I back off on the load a safety margin. Vernon Speer said that should be -6% powder change in 1956.

Right now I am running -4% in my 7mmRemMag. I will see if I get away with it. </div></div>

Thanks for that info. I was out again today, shooting the same load that i've been shooting for a while. 56 degrees, new lot of RL17 powder and it was HAWT. STIFF bolt lift, ejector marks, had one round that had the primer fall out when I extracted the cartridge. 2 others shows dark rings around the primer.

I knew something was up when I was getting 2620-2640fps (reading on 2 chronos). I'm going to be going through and measuring all my primer pockets to discard those that are out of spec. The case that had the primer showed significant primer pocket expansion.

It's back to the drawing board for my load. I'm going to back off for sure, gotta go back to my load development and look for the 2500fps load and work around that.

I think that I have unrealistic goals of a 1300 yard cartridge, sure I can likely get the aiming point of a deer at that range, however I only have a 10x scope, so anything much smaller than that is going to be quite difficult to get a bead on.

I still love the wind bucking ability of these 208's. The guy I went with is shooting 155 Scenars, and was holding 2-3moa for the wind at 800. I dialed 1moa and was banging the target like a drum.

Branden