17hm2 detonation part 2

[dewman]

So this morning I went to pry the blockage out. Surprise! All that came out, and popped out easily, was the bullet still sitting in the throat. Tip intact(messed up by the rod I used to tap it out) boattail fine. The other 5 boxes have different lot numbers so what to do with them? It sure looks like weak brass gave out? Ordered new magwell & mag. Don't know about the fast on the box but I sure as hell can vouch for the furious!! IMG_2258.JPG IMG_2262.JPG IMG_2264.JPG

[dewman]

I'll give the gun a thorough cleaning and one over but the chamber and bore look fine. No scratches or deformation.

[PigHunter]

I would guess weak brass too. But is it possible the firing pin struck a little too hard? It's hard to tell from the photo if that's where the case head blew out.

[fitch270]

So the rest of the rifle is ok then?

Call or email CCI about it if for nothing else to let them know that lot may have issues. Document everything and get their take on what to do with the other boxes. You’ll be helping them and possibly others.

Have you considered shooting it single shot without the mag well?

[dewman]

IMG_2266.JPG PH: Oriented to the way it was chambered (firing pin at 12:00) you can clearly see the unsupported part of the rim disappeared. The rims open crack runs 4:00 to 8:00.
Fitch: rest of rifle appears o.k. I will put it up till the parts come in and I decide what to do about the ammo. No desire for it to run as a single shot, though they do make replacement mags for that very purpose. Already pulled the scope. I think it's earned a trip to the safe for awhile.

[fitch270]

Sorry, I was thinking maybe you might test fire it once or twice before putting new parts in, not really using it as usual. My minimalist typing being misleading once again.

I wouldn't pull a bullet from that lot down but I'm curious how much powder space is left in the casing when they're loaded. I've pulled .22 duds and there's not much powder in them, seems reasonable an over load or double charge was possible. The middle pic up top it looks like the split in the case side runs from the top edge of the neck back down. Appears the case completely let go, but I'm no expert.

[dewman]

I wii try it out for sure down the road but I just want it to look normal even if it turns into, heaven forbid, a parts gun. If it wasn't for the bolt body I'm convinced the whole rim would have blown off. Didn't miss doing that by much. I keep handling the case over and over just trying to get an aha! moment. 🙂⚡️😳☹️😞😣

[FirstBubba]

I've been studying the photo also.
The way the case cookie cutters around the cuts in the base of the bolt face, I'd check some spent cases to check for the thickness at the base of the case.
The base of the case was thin OR an overload imprinted it on the bolt face. Like a flattened primer on a hot load.
For what ever reason, powder charge, weak case or blocked bore, the load was almost too hot for the bolt to handle.

Also noticed there was blow by where the firing pin struck the case rim. I'm thinking hot load.

[dewman]

FB: Didn't notice the firingpin hole till you mention it. Now I know where the crap that caught my face came from. Dang that's a tiny hole for how much I caught in the face.

[FirstBubba]

Did you notice any substantial difference in the sound of the shot?
...louder?
...muffled?
How about the folks shooting with you?
Did they detect a difference in the sound?

[dewman]

Did you notice any substantial difference in the sound of the shot?
...louder?
...muffled?
How about the folks shooting with you?
Did they detect a difference in the sound?

No one was beside me when I shot. As for me I was wearing a sock hat and had my hood up. Startled by getting blasted in the face is all I remember.

[dewman]

Cci has been emailed

[jhjimbo]

IMG_2266.JPG PH: Oriented to the way it was chambered (firing pin at 12:00) you can clearly see the unsupported part of the rim disappeared. The rims open crack runs 4:00 to 8:00.
Fitch: rest of rifle appears o.k. I will put it up till the parts come in and I decide what to do about the ammo. No desire for it to run as a single shot, though they do make replacement mags for that very purpose. Already pulled the scope. I think it's earned a trip to the safe for awhile.

The M2 round operates about 40,000psi. Can you imagine a high intensity cartridge like a .300WbyMag that operates over 65,000psi.