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bolt face gas cutting ?

Steve Ladino

I have seen this gas cutting twice and chalked it up to a bad primer long ago. Recently I saw it the second time in a Rem. Bolt action with H1000 , 220 bullet, WW Mag Pr. WW New Brass. This was a below Max. load but not lite.

In this case the primer has a black smudge all around its circumference
after firing and a take off smudge line from the primer that cuts the bolt face. The primer surface showed some cratering but not flattened along with normal extraction effort. It was in the beginning of the firing session, after a few shots.

I'm curious to hear from anyone on the theories that could cause this or preferably an absolute diagnosis. Thanks
 
Simple - gas is escaping around the primer after ignition. Could be the case's primer pocket, could be the primer itself; thin walls, softer material, slightly smaller OD than others in that batch... or a combination of all three.

If the black smudge isn't uniformly round, or is just in one spot, then something's not fitting something else in that spot where the smudge extends farther than elsewhere.

Remember the Challenger disaster?

Primer cups can have defects like anything else man-made. When the pin hits the cup the resulting pressure shows up as gas leaking past where that defect's opened up.
 
spclark said:
Yeeeouch!

That erosion was from just ONE primer leak event?
Click to expand...

NO. The primers did not fall out, I took the pics when I got home and inspected the fired cases in their boxes and the bolt face.

I was prairie dog shooting, blazing away at them without looking at the cases as I ejected them, and noticed the gas cutting later when I was cleaning the rifle. Multiple primers failed at the radius. The primer manufacturer covered the cost of the bolt repair and supplied me with new primers, which is all I asked for. I was very satisfied with their response.

This was a time when it paid off having the case, powder, bullet and primer LOT numbers recorded on each box of ammo I loaded. It also allowed the manufacturer to look into their data.
 
powderbrake said:
NO. The primers did not fall out, I took the pics when I got home and inspected the fired cases in their boxes and the bolt face.
Click to expand...

My apology; you'd not said 'primers' in your original post. I took that to mean it was just the one incident that had such a dramatic effect on your bolt, why I asked for more info.

Glad the manufacturer stood behind their product and made good on the damage to your equipment.
 
spclark said:
Simple - gas is escaping around the primer after ignition. Could be the case's primer pocket, could be the primer itself; thin walls, softer material, slightly smaller OD than others in that batch... or a combination of all three.

If the black smudge isn't uniformly round, or is just in one spot, then something's not fitting something else in that spot where the smudge extends farther than elsewhere.

Remember the Challenger disaster?

Primer cups can have defects like anything else man-made. When the pin hits the cup the resulting pressure shows up as gas leaking past where that defect's opened up.
Click to expand...

All this is possible, but I think the most common cause is over-used cases with enlarged primer pockets.
R.G.C
c-g-designs.blog4ever.com
 
For a little while Winchester had an issue with the cups on their large rifle primers. I have had one fail the same way. I relegated them to light, cast bullet loads and they seem ok for that. WH
 
Steve Ladino said:
I have seen this gas cutting twice and chalked it up to a bad primer long ago. Recently I saw it the second time in a Rem. Bolt action with H1000 , 220 bullet, WW Mag Pr. WW New Brass. This was a below Max. load but not lite.

In this case the primer has a black smudge all around its circumference
after firing and a take off smudge line from the primer that cuts the bolt face. The primer surface showed some cratering but not flattened along with normal extraction effort. It was in the beginning of the firing session, after a few shots.

I'm curious to hear from anyone on the theories that could cause this or preferably an absolute diagnosis. Thanks
Click to expand...
How many times was the case reloaded , did you use any tool in the brass to uniform pockets ?
Did the primers seat normal or could you push them in with finger pressure ?
I had one customer trying to superglue them in , for one more reload . I suggested he take up golf !
 
Robert said:
. . . I think the most common cause is over-used cases with enlarged primer pockets.
Click to expand...
This matches my experience. Loose pockets cause leaking around the wall.

Over-chamfered pockets with high pressure can cause pinholes at the radius. In my experience a primer in a correctly chamfered, snug pocket will not leak until the pressure is so high it blows back out the pinhole.
 
Winchester primers are notorious for this. I only use Winchester primers in previously crimped LC or other military brass.

If you use Winchester primers in Federal cases then there WILL be gas cutting!
 
Ggmac said:
How many times was the case reloaded , did you use any tool in the brass to uniform pockets ?
Did the primers seat normal or could you push them in with finger pressure ?
I had one customer trying to superglue them in , for one more reload . I suggested he take up golf !
Click to expand...
New Winchester brass and new Winchester primer along with moderate H 1000 amount , I agree that loose pockets will cut but not always. Getting long life with Fed. 08 Military 300 Win Mag. brass and with Rem. 30-06 brass and most all brass that I don't bump more than a couple if any.
 
Steve Ladino said:
New Winchester brass and new Winchester primer along with moderate H 1000 amount , I agree that loose pockets will cut but not always. Getting long life with Fed. 08 Military 300 Win Mag. brass and with Rem. 30-06 brass and most all brass that I don't bump more than a couple if any.
Click to expand...
Thank you for replying !
 
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