Failure at the range today.

[fkimble@charter.net]

Looks to me like a classic out of battery discharge. The case was not all the way chambered leaving the unsupported case head hanging out. Could have been due to an overly long seating depth or a resizing mistake.

Frank

 

[Krogen]

I "got away" with it until the phone rang. I was at my back yard range and had a 5 minute conversation while the round sat in a hot chamber.

That right there is a concern in my book. Unwise to direct your attention away from a loaded firearm. You do get points if you flipped the safety on.

 

[209jones]

You had the urge to try it, found out it wouldn't work, got away with it this time. Lots of folk out there have done and are doing stuff they probably shouldn't, and know it. My first 2-3 yrs of reloading, I learned about max loads and primer pocket expansion, bad (recalled) powder lots, "softer" brass, all the hard way to some extent, got away with it. Learned about hangfires a few yrs later with reduced loads. Few yrs ago I learned about misprints on a very reputable website, fortunately, I'd printed the before and after of the page. That's life with reloading, sometimes, even when being careful, it can surprise you.

 

[Dr. Matt]

That right there is a concern in my book. Unwise to direct your attention away from a loaded firearm. You do get points if you flipped the safety on.

Another good point and why at the ( public ) range my phone stays in the truck. Yup safety was on.

 

[Dr. Matt]

Looks to me like a classic out of battery discharge. The case was not all the way chambered leaving the unsupported case head hanging out. Could have been due to an overly long seating depth or a resizing mistake.

Frank

I have a spread sheet with all the resizing measurements. Definitely will be going over the numbers tonight.

 

[Krogen]

Thanks for being so forthright Dr. Matt, and sharing with us the troubles you've had. I much prefer learning from others headaches when I can.

 

[243winxb]

Unitah

Is a bolt action?

The Uintah Precision UPR15 is a true BOLT ACTION upper for your mil-spec AR15 lower. The UPR15 brings the accuracy of a BOLT ACTION RIFLE to the most popular platform in the United States.

 

[Dr. Matt]

Yes. I kinda love this thing.

 

[Steve Donlon]

After sleeping on it, these are my thoughts.
I made a series of mistakes. The first was trying to make a 5.56/223 Wylde chamber shoot like a 308. I put safety on the back burner and focused on down range performance. I didn't see any pressure signs- until I did. But why?
The load work up for with Lupoa brass worked well for hundreds of rounds. The brass was on its 5th reload. I changed a component with out working up the load properly and went straight to neck tension and seating depth. This was a mistake, no excuses.
I "got away" with it until the phone rang. I was at my back yard range and had a 5 minute conversation while the round sat in a hot chamber. This removed any ( if there was any) safety margin left. I don't have my phone with me at the public range so this has not happened before. Now I need to go back and rethink the Lupoa loads just in case one of them gets a hot soak.
"Never exceed max load" means never exceed the max f'in load. Thanks for the comments. Lesson(s) learned.

People do that all the time, trying to make what they shoot some thing better than what they have. Just get a different round for 1000 yards. You will always be chasing your tail with a 223 at 1000 yards.

 

[Dr. Matt]

Agreed.

 

[Straightshooter1]

20 inch barrel , but still a dumb mistake. I unloaded the remaining rounds and made notes about what I did in the log book.

Ahh, that velocity makes more sense to me, but the pressure is still .

 

[AckleymanII]

It is fairly common knowledge that Nosler brass has soft case heads. When Changing to Nosler brass, consider a new load work up, and do not expect the primer pockets to last very long. Nosler = Federal brass in soft case heads.

 

[Dr. Matt]

Yes. I kinda love this thing.

She gets a can Friday. The wait is finally over.

 

[searcher]

Looks to me like a classic out of battery discharge. The case was not all the way chambered leaving the unsupported case head hanging out. Could have been due to an overly long seating depth or a resizing mistake.

Frank

I think there would have been much more damage, had the round been out of battery. Would have likely destroyed the rifle.

 

[searcher]

Unless I missed it elsewhere, you said you used .002" interference on your necks. For an A/R, that is usually not enough to stop the bullet from slipping in the case when going through the loading cycle. Applying .002" usually leaves less than that after brass spring-back. Fine for a bolt gun - but not an A/R. I'd cycle a few dummy rounds through your action to see if the bullets are slipping. If one was pushed way back further than the others, that could cause a pressure differential on top of what was a hot load to start with. I'd go at least .003".

 

[brokeasajoke]

Unless I missed it elsewhere, you said you used .002" interference on your necks. For an A/R, that is usually not enough to stop the bullet from slipping in the case when going through the loading cycle. Applying .002" usually leaves less than that after brass spring-back. Fine for a bolt gun - but not an A/R. I'd cycle a few dummy rounds through your action to see if the bullets are slipping. If one was pushed way back further than the others, that could cause a pressure differential on top of what was a hot load to start with. I'd go at least .003".

I believe this is a bolt action upper from posts 47 and 48.

 

[K22]

Case head expansion is one of the sure signs of over pressure but requires some expertise and special equipment to measure accurately. However, excessive case head expansion usually manifests itself with loose primer pockets and is the most expedient way to alert reloaders of a potential pressure issue.

Historical Note:
Vernon Speer did a lot of research on case head expansion and pressure. The most precise way to measure it is with a knife edge micrometer. A micrometer that is accurate to .0001 (that's four places) is required. Their testing revealed that an average expansion of .0003" with no individual reading over .0005" was indicative of pressure in the 50,000 c.u.p.

 

[Conaso]

No one mentioned the contribution of the primer.

CCI 41 is a Small Rifle Magnum primer, just like the CCI 450, but the 41 has the anvil positioned slightly farther from the primer head. I never use magnum primers in .223 Rem, not necessary; #400s or BR4, match primer with a thicker .025" cup. And I never felt the need for #41s in a bolt action.

 

[Krogen]

Case head expansion is one of the sure signs of over pressure but requires some expertise and special equipment to measure accurately. However, excessive case head expansion usually manifests itself with loose primer pockets and is the most expedient way to alert reloaders of a potential pressure issue.

Historical Note:
Vernon Speer did a lot of research on case head expansion and pressure. The most precise way to measure it is with a knife edge micrometer. A micrometer that is accurate to .0001 (that's four places) is required. Their testing revealed that an average expansion of .0003" with no individual reading over .0005" was indicative of pressure in the 50,000 c.u.p.

Ken Waters used to promote this method. He said it was essential to use new brass. Otherwise, work hardening of fired brass affected the results. I recall reading somewhere that head expansion as a pressure indicator was criticized due to the sensitivity of the measurement. Surface finish, dings, roundness and manufacturing anomalies in general make measuring to 3 or 5 tenths impractical.

 

[K22]

Ken Waters used to promote this method. He said it was essential to use new brass. Otherwise, work hardening of fired brass affected the results. I recall reading somewhere that head expansion as a pressure indicator was criticized due to the sensitivity of the measurement. Surface finish, dings, roundness and manufacturing anomalies in general make measuring to 3 or 5 tenths impractical.

You're correct. It requires a knife edge micrometer accurate to .0001 (four places). The Speer study also contains a lot of conditions regarding cases and the number of firings, etc. and their measurement data was confirmed with pressure data (c.u.p.) It's an impractical method for most of us but excessive case head expansion often results in loose primer pockets.

Therefore, loose pockets should be a warning sign to re-examine your load and look for other confirming signs of high pressure.