Followup for Kaboom Today by OP gingerman/DoneNout

[buckbrush]

I think these two threads pretty much cover it;

Bullet Construction vs Lethality

www.longrangehunting.com

Did Wipeout Products Ruin My Barrel?

I let Wipeout Accelerator sit in my barrel for 45 mins yesterday. When I patched it out, rust colored product poured out the end. Now I have what looks like corrosion etching/deposits through the bore. I called Wipeout and was reassured I wasn’t seeing rust, just the chemical reaction between...

www.longrangehunting.com

Here is a link to the original kaboom thread in case anyone is interested - it may be hard for some to locate.

Kaboom 💥 Today 😟

Things shooting good with 1x fired 708AI brass. (Lapua) 12th round shot and gun explodes out the mag well, ruptures mag and extractor. Ruptured case easily fell out the chamber. The separation line looks too clean. Bad brass? 11 fired cases look fine. No serious pressure signs.

www.longrangehunting.com

Carnage and damaged parts seem to follow this guy.

 

[Culpeper]

One more thing. I think the two brass with expanded pockets and this blown cartridge were fired back to back to "Kaboom".
I cannot prove it but it's easy to tie these together.

If I remember right the OP was answering negative to some of the usual over pressure questions. Guess he didn't understand that some people were correct. You went above and beyond, which is commendable.

 

[Culpeper]

.003" is ABSOLUTE minimum, even this dimension can cause issue if you do not measure your brass neck wall accurately.

Cheers.

Post in thread 'Kaboom Today ' https://www.longrangehunting.com/threads/kaboom-💥-today-😟.337437/post-2882835

 

[Culpeper]

MagnumManiac,
Do you still believe excessive pressure caused none of this? As you posted in mid-August? You were absolutely certain. Too funny

MagnumManiac said

"I honestly believe you don't know what you're talking about. An excessive pressure event, not a case failure, ALWAYS results in case FLOW into every possible recess in the bolt face, and obviously when the case ruptured due to a case defect, the gas was correctly directed into the mag well. Like it's supposed to…
My question to you is…how many ruptured firearms have you seen and how many have you determined the cause of such ruptures?
I have seen dozens in myriad of scenarios, such only 1 being caused by a case rupture very similar to this. Excessive pressure, nor excessive headspace caused any of this."

Kaboom 💥 Today 😟

Well, its been ruled as my fault. I am not disbelieving the notion, but I am surprised that a few thou stretching on 1X fired case causes the rupture. I do not believe that for a second…that rupture occurred right where the case is turned for the extractor groove and where the extrusion occurs...

www.longrangehunting.com

 

[Muddyboots]

Bob,
Wow! Thoughtful, detailed analytical review of a very complicated incident. Speak with data is standard manufacturing investigative term. Many can learn from that concept. Many incidents do not have just one cause. Some incidents are result of cascading effects.

Well done! Thank you!

 

[Carey Farmer]

Bob,

Really good investigation and write up - sure appreciate it.

After getting a batch of new brass (from a premium manufacturer) with donuts in every single piece, I started neck turning all of my new brass (with carbide cutter pilots), and making sure I cut into the shoulders a fair bit.

Neck turning is pretty tedious. I'm probably over-doing it, but after reading your write-up I'll probably continue doing so.

 

[flyguy1]

Wow, thanks for that. I am a novice in reloading compared to most here. I don't fireform, but I do neck down 8mm brass to make .257 STW. No problems so far. Am I at danger of these donuts?

 

[ButterBean]

Amazing analysis. Thank you!

X-2 Thank you Bob

 

[Calvin45]

Wow, thanks for that. I am a novice in reloading compared to most here. I don't fireform, but I do neck down 8mm brass to make .257 STW. No problems so far. Am I at danger of these donuts?

I'm interested in the answer to this as well.

I've never had issues necking 264 win mag and 7mm rem down to to .257 weatherby (short neck but no donuts or anything like that that I'm aware of)

In the future I do intend to build my first wildcat, and it'll be a big .25 cal, something bigger than a .257 bee. The two strongest contenders are either a .25-300 weatherby or a .257 STW.

 

[charlie 7]

So, you bought same second hand cases, no info of the number firings nor how stiff were the loadings.

20% of the acquired cases had expanded primer pocket. In my mind the expansion of the primer pocket is an obvious sign of excessive pressure.

-OP finished neck wall thickness after fire forming to AI and turning to obtain .007 diametral neck clearance. OP did this due to inability to slide a new bullet into the fired AI neck. Donuts present after neck sizing 308 to 708. OP used a mandrel to push donuts to the o.d., then turn necks. Op had almost zero diametral neck clearance after fire forming.

This bit is incoherent and difficult to understand.
The donut could be removed by reaming but I think it could not be pushed outside by any mandrel. When neck turning, it is good idea to come a bit up the shoulder to create a small undercut in to which the donut could be pushed out (firing).

In my mind the kaboom happened because the projectile was held tight
in the case's neck, held with no clearance (for the donut) in the neck portion of the chamber.

The cracks in the case would be perfectly visible if you could polish the
milled surface.

 

[victor3ranger]

I am concerned about this necking down as well, I have 8rem, 375 H&H, 300 H&H, 300 weatherby all to be necked down and fireformed with the COW method into 7STW.
Makes me a bit nervous

 

[Calvin45]

I am concerned about this necking down as well, I have 8rem, 375 H&H, 300 H&H, 300 weatherby all to be necked down and fireformed with the COW method into 7STW.
Makes me a bit nervous

Also…I've formed .358 Norma brass from 375 HH and also 458 Lott brass. No issues at all but this thread has me wondering…

 

[victor3ranger]

Also…I've formed .358 Norma brass from 375 HH and also 458 Lott brass. No issues at all but this thread has me wondering…

Me too

 

[Bob Wright]

Me too

My experience with donuts showed up first on targets. Crazy vertical stringing.
Then, on another reload, I could feel at the bottom of the stroke while seating past the neck/shoulder, a resistance that was noticeable only as I was partially seated.
I could see into the neck, a shiny band at the neck/shoulder .
I tried a mandrel/turning operation to no avail.
I ordered the K&M reamer pilot and neck turner and that finally got it under control.
Wildcats are known for these problems at least occasionally.
Just have to be aware and prove to yourself you don't have them.
I lost quite a few brass during these efforts to fix it. Primer pockets were the first to go on my Nosler brass.