300wm primer rupture

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TrevorJ

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Hey Nutz,

Preface: I am new to reloading, have only been at metallic reloading for a couple of years. Shotgun reloading for a few years before that. I use a single stage press for metallic, still on the same lot of brass, primers, powder, and bullets for this story.

I was at the range today, trying out the new range rabbit know your limits kit at 200 yards. Using a load that I have shot literally 200+ rounds of at other targets. I was timing my shots to do about one shot a minute and shooting strings of 10 rounds, in this case. When I had a round come out of the chamber with a ruptured primer. Scored the bolt face, and put a bit of a damper on my range day!

Wondering if a new bolt or bolt face is required, or input on what may have happened. How not to do it again. Brass loaded 6 times.

My load uses pvri brass, cci 250, Berger 210 vld, over 69.7gr of H4831sc. The Berger manual suggests 66.5 to 70.2gn of powder.

I shoot this load in a savage 111.

Pictures to follow.

Ruptured primer
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Bad picture of the scored bolt face
20181013_163601.jpg

Round after rupture, to look for primer deformation.
20181013_173245.jpg

This thread probably exists on the forum elsewhere, with a similar story, but what's one more thread?
 

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Last edited:
You need to remove the primer and inspect the primer pocket and the primer. And you need to determine if the gas leakage was from the side of the primer pocket past the primer cup or if the rounded edge of the primer ruptured.

If the gas leakage started in the primer pocket you may have had a loose oversized primer pocket. Think of a cars engine with a scored cylinder and gas leakage past the piston and rings.

If the primer cup let go at the rounded edge you had a bad primer that was weakened when forming the edge of the cup edge.

Below the photo is from a AR15 reloading forum, and the person who posted the photo said he wasn't worried about loose primer pockets. And he would just replace the bolt when it got bad enough.
This is a very bad idea and brass cases are a expandable item and should be tossed when the primer pockets get loose.

VMkEdYr.jpg


The person who posted the photo was still using this same pitted bolt and it was not causing the primers to flow into the pitted bolt face.

Bottom line, the pits are ugly but as long as the primer does not flow into a pitted area and weaken the primer edge you should be fine. And the good news is the Savage bolt heads are replaceable and simple to fix, and the entire bolt does not need to be replaced.

The Savage replaceable bolt head is held in position by the bolt head retaining pin.

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A while ago, there was a rash of Winchester LR primers doing the same thing.
At the time I mentioned having that experience with many different brands of
primers over the years. Now we have a CCI that has failed in the corner of the
primer cup. Your bolt face should be fine to use. Dave.
 
Eagleye said:
A while ago, there was a rash of Winchester LR primers doing the same thing.
At the time I mentioned having that experience with many different brands of
primers over the years. Now we have a CCI that has failed in the corner of the
primer cup. Your bolt face should be fine to use. Dave.
Click to expand...

yes happened to me twice from the same lot
and I trashed 500 of them
and neve bought Winchester again
 
I had the exact same occurence with a Federal GM215M primer this spring. My primer failed on the corner and cut the bolt face. I asked a gunsmith if he had replacement bolt heads in stock but he said to just run it, no problem. I emailed Federal about it but no response. I've used about 200 other primers from the same lot with no problems so I'm not going to worry about it.
 
How tight were those primer pockets when you primed this brass?

6 near max loadings on any brand of case often tend to enlarge the primer pockets somewhat.
 
'Boo said:
How tight were those primer pockets when you primed this brass?

6 near max loadings on any brand of case often tend to enlarge the primer pockets somewhat.
Click to expand...

From what I can remember, they were tight enough for me not to notice them being overly easy to seat the primers. As a precaution I will be pitching most of this lot of brass, as I (and most of you) suspect they are near the end of their life, given the loads I have been using.

Thanks for the post!
 
Below you can order pin gauges .0005 smaller in diameter than the primers you are using or order the Gauges below to check primer pocket diameter.

I mainly use them to check military once fired primer pockets after removing the crimp or checking range pickup brass. I load ammo for my two sons and Dad isn't going to be blamed for a etched bolt face.

I also use a Lee depriming tool to check for loose primers, if the primer moves with light finger pressure the case goes in the scrap brass bucket.

m1PlERq.jpg


BALLISTIC TOOLS - SWAGE GAGE™ PRIMER POCKET GAUGE

https://www.brownells.com/reloading/measuring-tools/case-gauges-headspace-tools/swage-gage-primer-pocket-gauge-prod71030.aspx

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