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Blown Primer

DaveB

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Sep 3, 2008
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Shelby County
Been hand loading since 1985. I have never had a safety kind of problem.

At the range yesterday we had a 22-250 case refuse to extract.

Bolt lift was sticky, as in a 16 ounce hammer smack was necessary.

Then the brass had be knocked out of the bolt face.

I was sweating what I would see. The bolt face looks okay but additional review is upcoming.

The primer blowout was located at the deepest point of the firing pin into the primer.

The case body was not scarred. Case head had some burning.

I unloaded 10 of the remaining 22-250 rounds. I measured each to ogive and OAL. Weighed each charge, checked case dimensions, weighed the bullets.

Nothing was out of spec. Brass that had never been loaded was checked for all dimensions. Nothing. Triple checked the powder, it was okay.

Then the thought came I had a squib and it was not detected. If that is the case I would expect a failed barrel, material in the bore, something. So far, I see nothing. I am going to check more closely later.

Some details:
I have loaded and shot this recipe for at least 4 years
43 grains Hodgdon Superformance powder
FC brass brand new never fired
Federal 210M primer
Nosler 60 gr partition
Browning A-Bolt Medallion

Any ideas? Have I overlooked something?
 
Sometimes in very rare occurrences the powder can sit in the perfect position inside the case to explode, rather than burn, creating a spike in pressure.
Maybe something entered the barrel after the shot, like a wasp.
Remote possibility the bullet was oversized by a few thousandths.
Possibly a higher powder charge or maybe the powder was in smaller grain size than normal which increased he burn rate.
Just a few educated guesses. Sometime we never do find out the answer
 
One more thought... I noticed that you were using FC brass - is this Federal or Frontier Cartridge? I'm not a fan of Federal brass for reloading, as I have had experience with inconsistent hardnesses and premature failure, but I've also heard (yeah, I know, the internet) of inconsistencies in internal capacities and weight of the Federal brass. I will only use it for youth/reduced loads

My brother (hunter0925) had a failure with 308 Federal Match ammo that sounds very much like your experience.
 
as hot as it was yesterday if you let the round that blew sit in the chamber a couple minutes with a warm barrel the powder could have cooked off and dramatically changed the burn rate,,thats why you will see warnings not to leave your ammo in the sun or in a vehicle on very hot days,,
I dont know that was what happened but if you are shooting an average load with ball powders and chamber a round in a warm barrel and dont shoot it right then and let the round sit in the chamber and get hot the powder can burn much faster than it should causing dangerous pressure spikes,,

pretty common with varmint rounds loaded hot with ball powders and shooting prarie dogs in a hot bbl,,

it seems if it had been an obstruction there would have been evidence of what happened that you could see with your eyes..
 
I have had factory federal GMM blow primers and scar bolt faces and also had multiple federal 300win give me case head separations on the first reload.
To your dillema, I would lean towards heat having spiked pressure if everything else checks out.
 
I have hot loads for some of my rifles that I will only use during cooler weather. The warm weather loads for those rifles are on the next lower harmonic node where the pressure is lower. The smart thing to do is work up summer and winter loads if you want them in the upper limits pressure wise. Since I got into pressure tracing, my eyes have been really opened. I have Smokeless Muzzleloaders in 30 cal, 40 cal, and 45 cal, with heavy barrels, shooting loads in excess of 60 to 65kpsi but those loads stay at home until cooler weather arrives.
Temperature can cause extreme swings in pressure, depending on the temp sensitivity of the powder. This is why powder manufacturers are making more powders that are less temp sensitive. RL16, IMR4166, etc

Regular yellow brass has a rating of approx. 50 to 60kpsi depending on hardness and alloys added. #630 Bronze, also known as Aluminum Nickel Bronze is a refined copper alloy with much higher yield strength. This is what we make our high end SML ignition modules from because it can stand very high pressures. I imagine that rifle brass is somewhere in between yellow brass and 630 Bronze, depending on grade and manufacturer. At some point, any brass case head will expand under pressure, allowing leakage around the primer.
 
The rounds were not warm, i picked one out of the same box and pressed it against my cheek when we could not work the action---no heat problem.

My Son found a tiny piece of brass in the lugs. We think this is what was stopping the bolt from opening. I am wondering just where did the piece come from and could this have interfered with the partition that was fired. It was about the size of a #7 shot but really mangled. You could not tell it was brass if it did not shine.
Of course, I had to use some force to get the bolt to open-the mangled could have been then.

I am currently preparing two 5-round groups for testing. One will be with RL19 (edit to correct: powder will be RL15) and the other Superformance.

This is an old pic...notice the indicated temp.
 

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The only two blown primers I've had were with a Tikka 7RM using once fired federal brass. They blew out the pocket in between the primer and the brass. Both times took out a small spot on the bolt face. When I got home I checked the other Fed brass and the primer pockets seemed loose. Haven't used Federal brass since.
 
Internal case capacity of the FC brass is not the same as the R-P brass.

The 62 grain charge of Superformance in the FC brass fills the case into the neck. With the R-P brass the charge is below the neck and the difference was noticeable with a casual glance. Worse, it appears to be random, not every case fills to the same level.

Starting to get a little uneasy with this brass purchase.

I think I best be starting a conversation with Federal. The vendor I use would simply re-stock the brass and pass this issue to the next guy in line. This inventory is probably going on the shelf.....are you ready....600 pieces. We shoot a lot at my place.
 
I sorted 15 FC pieces by weight. 10 were between 170 and 171.4. 5 were 173 to 176

3 R-P cases each weighed 160.

I am going to check volume tomorrow.
 
If they are all fire formed to your chamber, water fill weight will give the most precise volume measurement.

It is never advisable to change brass without retuning the load.
 
The cause was most likely a round touching the lands.

I was checking my stash of loaded 22-250 rounds by chambering and ejecting every round.

I found two more over length, one so much so that when the brass was extracted the bullet stuck in the lands and powder went everywhere. This triggered my memory.

I know exactly when and how the error occurred. I had a seating die improperly adjusted and after discovering the error failed to unload all of the overlength rounds.
 
Yep. I am generally pretty meticulous with my loads so any kind of event like this one makes me chase it until I get a resolution.
 
Having worked for the Japanese, Root cause analysis and Reoccurrence prevention were drilled into my brain.

Root cause? Root cause in the end is always management because they had not yet determined root cause and implemented reoccurrence prevention or that the reoccurrence prevention fix was not implemented or followed. Your root cause was not checking the first round out of the die with a comparator to confirm length.

I use a simple check for this. I set up the die and adjust it until the comparator measured part is correct. Then, slip your calipers over the cartridge as to measure COAL. Open them an extra .002" and lock them with the thumbscrew on top. Now, check each and every one coming out of the die to be sure they pass thru the calipers.

Another method I have used for rounds that I load a LOT of the exact same projectile is to machine an aluminum GO/NOGO gage.
 

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