And Today's Lesson . . .

[Boomer]

Actually it did, the .002" expansion across the web was a sign of excessive pressure.

I don't make a habit of taking a micrometer to the range, so no, there was no visible clue which I have become accustomed to reading when working up loads. As for a web expansion of .002" being dangerous, don't tell Federal, their factory stuff expands the web up to .002 as well.

Edited to add . . .
The question then becomes at what point does the expansion of the case from pressure exceed the elastic limits of the brass. Some believe that any measurable change from a piece of virgin brass is cause for concern. I normally believe the wall has been hit with the first indication of a sticky bolt, which in the case of this rifle requires a web expansion of about .003". Again this is for purposes of determining where not to go, as slight changes with respect to the propellant charge, cartridge OAL, and ambient temperature have dramatic effects on pressure.

 

[Republic of Alberta]

Have you calculated the additional case capacity you are gaining by seating the bullets long then use that to calculate/estimate the aditional potental velocity gain you will get?

Would be interesting. If I were smart (I'm not) that's wat I would do.

 

[Moosetracker]

Have you calculated the additional case capacity you are gaining by seating the bullets long then use that to calculate/estimate the aditional potental velocity gain you will get?

Would be interesting. If I were smart (I'm not) that's wat I would do.

Just purchase Quickload and let the program do it for you, along with numerous other useful reloading details, like speed, pressure, barrel timimg, etc.

 

[stubblejumper]

I don't make a habit of taking a micrometer to the range, so no, there was no visible clue which I have become accustomed to reading when working up loads. As for a web expansion of .002" being dangerous, don't tell Federal, their factory stuff expands the web up to .002 as well.

Anytime that I am working with data that may not be as proven as I would like, I do carry a dial caliper with me, and I use it between groups to measure web expansion.I am not saying that a web expansion of .002" is dangerous for a single shot, but it certainly is an indication of more pressure than I want to have going on in my gun over any considerable time period. I have seen factory loads that displayed excessive web deflection, some Weatherby loads, and some early 300wsm loads, but after seeing the expansion, the person quit purchasing those loads.

Had you taken a dial caliper to the range and measured web expansion, and heeded the measurements, the incident would not have occurred. But since you don't take a measuring tool and measure web deflection at the range, the incident did occur.

 

[wapitiwhacker]

I am neither ballistics expert or a metallurgist but I continually try to learn from instances such as this one (learn from the mistakes of others as you won't live long enough to make them all yourself).

Some people swear by case head expansion, others seem to shun it. A couple of points to ponder when employing it. I have read that measuring case head expansion of virgin brass does not yield reliable results. Only measure fired neck sized brass. Due to work hardening, brass fired more than five times may also yield questionable results. Max allowable expansion seems to vary, but from what I understand it is in the tenth of a thousand range ( say .0002 to .0005 depending on who you read), well below the .00x threshold.

There are many possible indications of high pressure, I think as many as possible should be checked and taken into account when undertaking an endeavor such as this, but the only truly safe, reliable way to know where you are, is through the use of pressure measuring instrumentation. If only it were that easy eh? my two cents, cheers!

 

[H4831]

For starters, I trust Boomer's judgement, along with only another, maybe two people, on reloading matters more than I would any of the other writers on these threads. I certainly admire him for writing this up on these threads, so all of us can benefit from his unfortuneate incident.
Regarding measuring the expansion of the webb, I too, quit using it as a determing factor. I have a good Millers-Falls micrometer I used to take to the range, but when measuring to .0001" there were just to many variables. Seeing factory loads going over what they tell us is too much expansion, plus getting different readings on the same case, depending how you turned the case, as well as different expansion with different brands of brass, makes one wonder.
I think it was Speer that used case measurement for getting their loads in their loading manual, instead of a pressure gun. But in their case, they were always working with the same brass in the same conditions, plus they pretty much just duplicated common loadings.
I always considered a sticking bolt as a sure sign of an overload, while keeping a close watch on the primer pocket. If several shots didin't expand the primer pocket enough to notice, as a new primer was inserted, then I considered I was not overloading.
It would appear to me that the cases Boomer was using behaved differently than does standard brass cases. Just my guess.
I have stated on CGN that I once blew a primer and I can assure you it is not a pleasant experience. I think the cause of mine was my failure to keep my 270 "plinking" brass properly trimmed, as it happened with a normal load I was reularily using.

 

[Eagleye]

Boomer; Were you using new brass or brass that had been fired once or twice? My take on brass web expansion over the years has been this:
A new case [even many factory rounds] will expand the web of the case somewhat. You mentioned Federal cases expanding up to .002" I have never seen quite that much, but have measured .0015" on initial firing.
Federal cases, in my experience, tend to be a bit "soft" anyway.
However, subsequent firings do not continue to expand the brass any appreciable amount unless they are quite stiff, pressure-wise.
I will not continue to use a load that causes my brass to continue to expand at the web after the first firing.
For example, if in new brass, I measure .0015" expansion, I am OK with that. But if that same case, using the same load expands more on the next firing, it is too warm to use, and I will back down to eliminate the head expansion.
I am glad you were not injured by this mishap, but I believe you were skirting around disaster a couple of grains before it found you.
I have used VV N550 a lot in a 700 Remington chambered in 8x57, and consider it a great powder. I am shooting some fairly stiff loads, [180 @ 2800+] but none of them are expanding case heads at all after the initial firing, which gives about .0008" in a Winchester case. Regards, Eagleye.

 

[Dogleg]

It takes guts to report a bad experience, a bad load, a bad hunting trip or a blown-up rifle.

 

[stubblejumper]

I always considered a sticking bolt as a sure sign of an overload, while keeping a close watch on the primer pocket. If several shots didin't expand the primer pocket enough to notice, as a new primer was inserted, then I considered I was not overloading.

Is it just a coincidence that as the primer pockets become looser, the web expansion increases, and if the web does not expand much, the primer pockets stay tight as well? It isn't overly difficult to understand the relationship between case web expansion and primer pocket diameter.

 

[H4831]

Cancel

 

[X-fan]

Actually it did, the .002" expansion across the web was a sign of excessive pressure.

I agree with this comment.
What troubles me is I would have gone to the next grain to confirm my high pressure suspicions.
I do this to check bullet impact (will it toss the bullet in hot weather?) and to determine if I should drop the load one or two grains.

I have done this hundreds of times.
With a normal load all one would have seen was a slightly deeper ejector mark and a similar or slightly larger case expansion reading.
In this case clearly something is different...I doubt we will ever know what the something is.

I would like to personally thank Boomer for having the ballz to publicly share his sobering misfortune.
I would not have done the same.

I am thankful for this information and as a result have made a few changes to my load development methodology.

1) I will be putting my mic back into the range bag for load development.
2) I will buy a another copy of Quickload (last copy disappeared with the old computer) for a sanity check on oddball loads like this one.
3) I will go 1/2 grain increments on 308 sized cases.

Those of us that think they know what they are doing need to pay attention here.
I for one am all bloody ears!

 

[Eagleye]

Is it just a coincidence that as the primer pockets become looser, the web expansion increases, and if the web does not expand much, the primer pockets stay tight as well? It isn't overly difficult to understand the relationship between case web expansion and primer pocket diameter.

Stubble; Exactly!! The relationship should be clear. The case head gets bigger, so does the primer pocket.
Any load that loosens primer pockets in 5 or less firings should be viewed with suspicion. [and reduced accordingly]
Obviously, a load that loosens primer pockets in ONE rifle may not do so in another.
Conversely, a load that appears OK in one rifle may sieze the bolt in another.
Thus the caution to use ammo developed ONLY in your rifle.
Regards, Eagleye.

 

[Boomer]

Boomer; Were you using new brass or brass that had been fired once or twice? My take on brass web expansion over the years has been this:
A new case [even many factory rounds] will expand the web of the case somewhat. You mentioned Federal cases expanding up to .002" I have never seen quite that much, but have measured .0015" on initial firing.
Federal cases, in my experience, tend to be a bit "soft" anyway.
However, subsequent firings do not continue to expand the brass any appreciable amount unless they are quite stiff, pressure-wise.
I will not continue to use a load that causes my brass to continue to expand at the web after the first firing.
For example, if in new brass, I measure .0015" expansion, I am OK with that. But if that same case, using the same load expands more on the next firing, it is too warm to use, and I will back down to eliminate the head expansion.
I am glad you were not injured by this mishap, but I believe you were skirting around disaster a couple of grains before it found you.
I have used VV N550 a lot in a 700 Remington chambered in 8x57, and consider it a great powder. I am shooting some fairly stiff loads, [180 @ 2800+] but none of them are expanding case heads at all after the initial firing, which gives about .0008" in a Winchester case. Regards, Eagleye.

Yes, it was new virgin brass.

 

[Boomer]

Hey guys, I appreciate the kind words of support. Thank you!

Purchasing Quickload won't be the worst money I've spent, but I guess I might as well wait till the strike is resolved.

I've had time to prep lost of .30/06 brass, apparently I won't be shooting .308 for a while.

 

[Dogleg]

Strike?

 

[Boomer]

Post Office goes out Thursday at midnight . . . last I heard.

 

[Dogleg]

I was hopeing to get into another strike thread. That and I have a rifle to send out one of these days, and would hate to see it stuck in transit.

 

[roberti11]

I was hopeing to get into another strike thread. That and I have a rifle to send out one of these days, and would hate to see it stuck in transit.

I am going to add a similar story but thankfully with a less disastrous ending.

I was working up loads for my 7mm Stair (wildcat based on .376 steyr) last year, I used quickload and was working up loads with N560 and Berger 180gn bullets. I found a perfect load and at that point there were no problems with my brass and no pressure signs.

I used 20 of the new 180gn Berger hybrid bullets again no problem. I then switched to my 'NEW' batch of 180 gn bergers, I immediately had a bit of trouble closing the bolt, and found that I was now 150 fps faster with an identical load under identical conditions (10 minutes after I had fired the 180gn hybrid bullets). I fired 6 of the new Bergers and had increasing difficulty in closing the bolt and stopped.

At no time were there any problems with primers, or bolt lift (I used my babyfinger to lift the bolt) or extraction.

When I got home I found that I could not fit these 6 cases into the shell holder when I tried to deprime them. I measured the case head and it had expanded considerably, after de-priming with a hand system i found that the primers would not stay in the hole.

It turned out the the batch of bergers were oversized and were causing pressure spikes that damaged my brass.

Lesson: There are no single rules, check every sign of potential brass failure, including measuring the web, I now routinely take my shell holder to the range as well as a caliper.

 

[rgv]

Hey guys, I appreciate the kind words of support. Thank you!

Purchasing Quickload won't be the worst money I've spent, but I guess I might as well wait till the strike is resolved.

I've had time to prep lost of .30/06 brass, apparently I won't be shooting .308 for a while.

if I was going to venture into things like 210 VLD's going fast from a 308, I'd spend my money on a Pressure Trace System, rather than Quickload.

All Quickload would have got you was the same basic loads you were trying out, with some projected pressure.

Pressure Trace may have stopped you at the 48 grains.

 

[H4831]

if I was going to venture into things like 210 VLD's going fast from a 308, I'd spend my money on a Pressure Trace System, rather than Quickload.

All Quickload would have got you was the same basic loads you were trying out, with some projected pressure.

Pressure Trace may have stopped you at the 48 grains.

What is Pressure Trace/how does it work?