AR15 popped out some primers today

I can crunch irresponsible amounts of 4064 under a 75gr bullet. almost 25gr to get to a "hopeful" 2700 from a 16" barrel. I honestly do no think, using proper powders, you can overstuff a case enough to cause damage in the short-term. now filling with 25gr of titegroup may yield different result.....

my biggest fear is somehow jamming a .300b.o into my rifle by accident.
 
What did the head of the case look like on those that did pop loose?
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one had a black streak from primer pocket to edge of case head, the others just a blackened primer hole. Regardless, I have retired all of these fired cases to my scrap brass bucket.

Spent a few hours yesterday pulling and emptying 400 rounds yesterday. And yes they were compressed, requiring two or three taps to get the powder to kick lose and pour out.

This whole event was/is an exercise in complacency. The day I loaded these I had loaded 100 rounds of the 55gr VMAX followed by 50 rounds of 69gr HPBT over Varget (compressed load). Then I decided to load the 55gr FMJs with H335. Having just loaded the compressed Varget loads it didn't click when seeing the nearly full cases of H335.

I use an 80's Dillon RL450 with manual powder bar. I do/did test weigh charges on each of the first 10 rounds and then check again at #20 and then proceed without further checking until I get to a half full hopper and add more powder, then I check the next couple rounds to confirm I am still throwing accurately.
 
Yeah, 29 gr of H335 powder is well over milspec.

I expect bulged case heads with that much powder charge.

Jimro
 
one had a black streak from primer pocket to edge of case head,
the others just a blackened primer hole.
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Did any of the case heads show a "brightened" brass area?

2u44pd2.jpg
 
I am really not trying to be rude here, but I can't imagine loading 400 rounds without stopping to double check charge weight. If any lesson is learned it should be some kind of pre-during-post QC. Even though my thrower hasn't ever changes more than a couple tenths of a grain here and there, I still stop and reset my scale and reweigh at least within 100 rounds of each other. Seriously, not looking down on anybody, I will surely make mistakes as well, just that checking charge weights in a semi-large batch of ammo should be part of your process. And it should include resetting scale back to zero.
 
OKaaayyyyy..... You were running 70-80,000psi (in a 55,000psi-rated cartridge).
That's pure/significant over-charge (vice any minor impacts like crimping differences).

Stay safe and double check.
(And light a few more candles Sunday) ;)
 
I am really not trying to be rude here, but I can't imagine loading 400 rounds without stopping to double check charge weight. If any lesson is learned it should be some kind of pre-during-post QC. Even though my thrower hasn't ever changes more than a couple tenths of a grain here and there, I still stop and reset my scale and reweigh at least within 100 rounds of each other. Seriously, not looking down on anybody, I will surely make mistakes as well, just that checking charge weights in a semi-large batch of ammo should be part of your process. And it should include resetting scale back to zero.
Click to expand...

Absolutely no hurt feelings or argument here. Ignorance may be forgiven (at least to a point), but complacency on the other hand, is just plain unsatisfactory. I do remain thankful this wake-up call came without injury to self or worse to others near by. And since I apparently lack enough common sense, I'll gladly take any prudent QC recommendations.

Time for me to go back and read some of those "stupidest things you've ever done reloading" threads I've been skipping over.
 
Calculating it two ways, I get anywhere from just below the proof pressure range to 10,000 psi above maximum proof. I'm guessing it's not actully over proof from the case condition and the fact most guns are not as tight as the test guns are, and so tend to shoot a little lower in pressure. But I'm not 100% certain. A chronograph would have decided the point.

When you develop a successful load, it's not a bad idea to take a piece of stainless wire (any big box store) and trim it to match the charge weight and keep it in a labeled small plastic bag or box. When you go to adjust your powder measure, set your scale, then place this trimmed weight on it. It should go to the correct number. If it doesn't, you have a scale problem or you put the wire in the wrong bag last time. Either way, you can explore the problem until you find the cause of it and before accepting that what you are weighing is correct. This works with either beam balances or electronic scales to confirm measurements.
 
Just reading brass gave me the 80ksi flow pressure.
But reading what UncleNick wrote, I went back to QL:
For 55FMJ/H335/29.9gr I got 97,000psi

Light several candles. :eek:
 
Hodgdon's Reloading Data Center ( http://www.hodgdonreloading.com/ ) shows a max load of 25.3 grains of H335 under a 55grain bullet with a standard small rifle primer . The CCI#41 "primers contain Magnum priming mix and should be treated as such."

I think your loads may be running warm even without the 5 grain over charge. What was your source for your load data?
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per my 11/14 records, load sources were: Hogdon, Lyman, Hornady, Speer, and Barnes. I calculated the average of these sources for my max of 25.9gr. I subtracted 10 percent to find my starting load 23.3gr and progessed in 2 percent intervals for three loads reaching 24.7 gr, and then progressed at 1 percent intervals until reaching the max 25.9gr. I was using the Dan Newberry OCW (Optimal Charge Weight) Method for identifying the best charge for this weapon.

FYI, Lyman says MAX is 27.0gr. How they came up with that is a mystery. Hence the reason I average and then start 10 percent below max and stop when over pressure signs are detected.

Although I haven't relied on it for finding most accurate loads, the Sierra reloading book has listed a couple "accuracy loads" that ended up being within 0.1gr of the loads my gun likes. Also the Seirra book lists separate data for 223 bolt versus AR15.
 
Oley,

The gun's chamber size has a lot to do with it, as do other factors. For example, Winchester case capacity was about 30.1 grains in data at 6mmBR.com, and LC averaged more like 30.5 grains in their measurements. More capacity means lower pressure. We don't know the hardness of your bullet. You are using a magnum primer, but not one that is as warm as some. Your lot of powder's burn rate could differ up to 3% from Hodgdon's reference lot. Your ambient temperature and Hodgdon's test temperature could differ, not to mention your rate of fire causing your barrel temperature to be different from theirs. All these factors create a grab bag of variables to account for that can easily bend pressures a fair amount.

For example, though magnum primers tend to make loads hotter, sometimes the opposite happens because they unseat the bullet before the powder really gets burning, and that results in a larger starting burn space for the powder. And that can be erratic when it is happening, as many a .22 Hornet shooter can tell you, with some load pressures high and some low.

Check your gun's performance with your established load and see if it has changed. If you have chronograph data from it under similar conditions, that's the best clue. If not, look at accuracy, where the gun throws ejected cases, etc. Those can be clues the upper is in pain. Taking a micrometer to checking the barrel diameter over the chamber for a bulge is another.
 
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