Blown Primer with 6GT =(
- Thread starter YerrowSniper
- Start date
I had a similar issue with a proof prefit and a TL3. Turns out if I don’t get every single bit of sizing lube off the case I will get serious pressure signs with even the lowest charge weights. Wiping down the cases with a paper towel after sizing isn’t enough. I have to tumble them. It’s pretty strange.
No, I tumble just the brass after sizing to get all the excess lube off.
Tumbling live rounds in a vibratory tumbler isn't a big deal. I don't do it any more because it is just a waste of media. I use denatured alcohol instead to rinse lube off cases or loaded rounds.
This is what I mentioned earlier, lube left on the cases is no bueno. The case is supposed to stick to the chamber wall when the "bang" goes off, lube fucks this up and causes pressure spikes.
For me it's: wet tumble > anneal > lube (spray on Lanolin + alcohol, swirl around in a container, you'll never go back to wax after) > size > dry tumble in corn cob media for 30-40mins to remove the lube before on to trim/chamfer/debur>prime>powder>bullet. The corn cob gets all the lube off AND as a happy side effect leaves some dust in the necks for seating bullets (no need to mess around with graphite or whatever and seating goes just as smoothly as if you did). I wouldn't be totally comfortable just casually wiping off the lube with any loads that are kinda pushing it, really any rifle rounds period, I like to be sure it's all gone.
Tumbling live rounds isn't as wonky as it sounds, Dillon actually recommends tumbling the lube off of finished handgun rounds in corn cob. I've done it for thousands and thousands of 9mm rounds. If you leave the lube on, and they sit instead of getting shot, after a while they become sticky. I've never done it to any of my precious rifle rounds though, mostly because I wouldn't want to mess up my expensive ass bullets lol.
For me it's: wet tumble > anneal > lube (spray on Lanolin + alcohol, swirl around in a container, you'll never go back to wax after) > size > dry tumble in corn cob media for 30-40mins to remove the lube before on to trim/chamfer/debur>prime>powder>bullet. The corn cob gets all the lube off AND as a happy side effect leaves some dust in the necks for seating bullets (no need to mess around with graphite or whatever and seating goes just as smoothly as if you did). I wouldn't be totally comfortable just casually wiping off the lube with any loads that are kinda pushing it, really any rifle rounds period, I like to be sure it's all gone.
Tumbling live rounds isn't as wonky as it sounds, Dillon actually recommends tumbling the lube off of finished handgun rounds in corn cob. I've done it for thousands and thousands of 9mm rounds. If you leave the lube on, and they sit instead of getting shot, after a while they become sticky. I've never done it to any of my precious rifle rounds though, mostly because I wouldn't want to mess up my expensive ass bullets lol.
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I did that when I measured the lands in order to have the bolt close freely.
But I’ll clean my cases when I work up my new load
I don't see a mention of the cartridge you're shooting, but the bullet weight is similar to what I shoot in my 6 Dasher and 6 x 47mm Lapua rifles, both of which I had developed severe problems with.
Match winning guns for several years (Stiller action with Broughton barrel, and Remington XR100 action with Krieger barrel), I suddenly started developing pierced primers, blown primers, bent firing pin, blown triggers (Timney, Jewell, Bix'n Andy). Drove me nuts, for two years. Tried many, many "solutions" to alleviate the problem. Nothing worked. Eventually, I had the same problem with my 6 X 47mm Lapua.
Then, a friend, who has competed in blackpowder competitions, realized some of those guns had a replaceable flash hole, which, when it erodes, is simply screwed out and replaced.
He asked me if I had uniformed the cartridge flash hole on my brass: the rest is obvious.
The 6 Dasher is based on the 6BR.
6BR and 6PPC (6x47mm Lapua, others too?) have a smaller primer flash hole (around .058) than the flash hole in other cartridges that take a small rifle primer (around.062).
When I "uniformed" the primer flash holes in my 6Dasher brass with a uniforming tool sized for the cartridges with larger flash hole, the pressure from ignition of the powder in my 6 Dasher load punched back through the enlarged flash hole, hammered and sometimes pierced the weakened firing pin impact point on the primer; the hot gasses, under pressure, continued through my bolt and into the trigger, causing multiple problems.
Had to trash all that brass, but I was thankful for my friend's insight. I no longer uniform my flash holes.
Match winning guns for several years (Stiller action with Broughton barrel, and Remington XR100 action with Krieger barrel), I suddenly started developing pierced primers, blown primers, bent firing pin, blown triggers (Timney, Jewell, Bix'n Andy). Drove me nuts, for two years. Tried many, many "solutions" to alleviate the problem. Nothing worked. Eventually, I had the same problem with my 6 X 47mm Lapua.
Then, a friend, who has competed in blackpowder competitions, realized some of those guns had a replaceable flash hole, which, when it erodes, is simply screwed out and replaced.
He asked me if I had uniformed the cartridge flash hole on my brass: the rest is obvious.
The 6 Dasher is based on the 6BR.
6BR and 6PPC (6x47mm Lapua, others too?) have a smaller primer flash hole (around .058) than the flash hole in other cartridges that take a small rifle primer (around.062).
When I "uniformed" the primer flash holes in my 6Dasher brass with a uniforming tool sized for the cartridges with larger flash hole, the pressure from ignition of the powder in my 6 Dasher load punched back through the enlarged flash hole, hammered and sometimes pierced the weakened firing pin impact point on the primer; the hot gasses, under pressure, continued through my bolt and into the trigger, causing multiple problems.
Had to trash all that brass, but I was thankful for my friend's insight. I no longer uniform my flash holes.
Yes you do. You have to have seen it when you clicked this thread as its in the title...
What do you think?
Attachments
To much pressure, possible cause brass to long, may be seating bullets to long , powder charge excessive. make up test loads with case trimmed to minimum length , minimum powder charge and charge 1/2way between max and minimum seat bullets to recommended COL not to lands . if no issues only change one thing at a time to determine what caused high pressure .
