Flawed Thinking

c-fbmi

c-fbmi

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Here's what happens when you think you know everything about something and you start making assumptions..........

This was only the third loading from new and came as a complete surprise to me. I just merrily full length resized them each time, because after all, it is a dangerous game rifle and one doesn't want snug fitting cartridges in a double where you have to fight to get them in and the rifle closed.

HOWEVER.....what I didn't know nor did I bother to research, 'cause after 40 years I know everything there is to know, or so I thought...........is that the factory .470 NE cartridges are formed with the shoulder pushed back significantly from the chamber dimensions. This is intentional and has been done since the days of cordite. It is to make them drop right in the chambers of the double with no interference at all and offers some reduction in pressure in extremely hot climates. Like firing standard factory loads in an AI chamber.

This is all fine and well when one knows this and can adjust their die accordingly, but when one knows everything already and assumes he should full length size for his double, life gets interesting and he gets a "wake up" call after ruining $200 worth of very high priced brass. The dies are made to return the case to original factory cartridge dimensions, not chamber dimensions, which makes a certain amount of sense I guess, but definitely moves the shoulder back more than 1/8" from chamber dimensions. Headspace is not affected obviously, because of the rimmed cartridge.

 
c-fbmi said:
Here's what happens when you think you know everything about something and you start making assumptions..........

This was only the third loading from new and came as a complete surprise to me. I just merrily full length resized them each time, because after all, it is a dangerous game rifle and one doesn't want snug fitting cartridges in a double where you have to fight to get them in and the rifle closed.

HOWEVER.....what I didn't know nor did I bother to research, 'cause after 40 years I know everything there is to know, or so I thought...........is that the factory .470 NE cartridges are formed with the shoulder pushed back significantly from the chamber dimensions. This is intentional and has been done since the days of cordite. It is to make them drop right in the chambers of the double with no interference at all and offers some reduction in pressure in extremely hot climates. Like firing standard factory loads in an AI chamber.

This is all fine and well when one knows this and can adjust their die accordingly, but when one knows everything already and assumes he should full length size for his double, life gets interesting and he gets a "wake up" call after ruining $200 worth of very high priced brass. The dies are made to return the case to original factory cartridge dimensions, not chamber dimensions, which makes a certain amount of sense I guess, but definitely moves the shoulder back more than 1/8" from chamber dimensions. Headspace is not affected obviously, because of the rimmed cartridge.

Click to expand...



We have more knowledge available at our fingertips than ever before, but the well only works if you drink from it.;)

Expensive lesson and maybe a pain in the butt to even find that brass?
 
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sad ratio of threads where something is learned, and shared through a touch of humility vs 1/2 MOA shooting.

Beautiful big bores are out of my league, but sloppy 'surp chambers get a chamber cast (pounded soft slugs) now...mostly to make better ammo, but partly out of curiosity on how far from spec they are. Motivation behind the chamber cut is the same...better to get 'er loaded in a time of need than worry about reloading for it.
 
Gate.........availability is pretty good through Tradex but the Jamieson stuff is 3 bucks a pop when it's available and the Hornady stuff is 4 bucks a pop with better availability. The Norma when and if you can find it is running around 5 bucks a pop.......

One doesn't need to dip from the vast well of knowledge when they already know everything.........right.:rolleyes::rolleyes::rolleyes::redface::redface::redface:

It would seem that all lessons have a price, whether that be the investment of time to properly research something or the dollars to cover the screw ups.

I have just been reminded again by another member here, who shall remain unnamed for now, that "no good deed goes unpunished"............and I must say that I did know better than to ship before receiving payment, but was just trying to help a young guy out before Christmas when dollars are understandably tight. Now it's March and I'm being ignored...........One does try from time to time to have some faith in humanity, especially a fellow CGNer, but inevitably it will come back to bite one in the ass..........
 
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Similar situation, at first I was full length resizing my 9.3x74R brass. Much improved case life by just neck sizing.

medium_heavy_zpswiblox7k.jpg
 
jeff270 said:
Holy shot!
I'll be checking my 450-400 brass.

thx
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Jeff, I don't know if this practice was used with all the big double NE cartridges or only the .470..........you might be OK

bigedp51.......no headspace issues, the case is not stretching back as the pressure builds it is flowing forward and causing the thinning and separation. This may be unique to the 470 specifically or NE cartridges in general. I believe it has to do with the case thickness or more accurately lack of. The whole case is quite thin and is allowing the entire case body ahead of the web to move forward before the pressure builds to the point that the case walls engage the chamber, thus causing the thinning and separation at this point. I should have picked up on this much earlier as I had to trim the cases every time I fired them, so obviously there was significant stretching going on somewhere.
But these little details would seem to be lost on someone who knows everything, and isn't paying the appropriate attention to the obvious signs. I'm relatively certain that back before I knew everything, that I would probably picked up on this at first firing............


buzzmagoo..........I don't think you grasp what is happening here. The rifle is not popping open upon firing, which I suspect may well be terminal for the shooter. The problem has to do with undersizing the cases when reloading. The separation happens with the rifle fully closed and locked.
As far as cuff links go.........I haven't owned a shirt with French cuffs for likely 50 years or more, can't see an urgent need for cuff links no matter how cool they may be........They'd make a cool button on my jeans though, buts it's always covered by my belt buckle.........I haven't thought of a good use for the heads yet but I should give it some thought because I'm going to have 50 or 60 of them here shortly..........Maybe I should put up a thread asking for ideas on what cool things I could do with 50 or 60 .470 NE caseheads, just as a testament to my unseeing arrogance...........
 
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c-fbmi said:
Here's what happens when you think you know everything about something and you start making assumptions..........



HOWEVER.....what I didn't know nor did I bother to research, 'cause after 40 years I know everything there is to know, or so I thought..........
Click to expand...

I have to be honest, I'd never thought I would ever hear you say that!;) Good on you.:cheers:
 
I don't know everything, yet, and I get that the brass flowed from the web to the point that the cartridge case separated but where did it go?
Is the neck thicker or is there a pile of trimming shavings on the floor, or?
 
Just checked some once reloaded brass against virgin (all Hornady).
After firing the neck shortened up by about 0.08''.
You can bet I'll be backing that sizing die up.

Thanks
 
Ah Steve, I am actually quite critical of myself sometimes when I do bonehead things, when I really should know better, as in this case..............It's not for lack of knowledge, it's more just being complacent, which I deem unforgivable, especially in myself.

Jeff.........so you're saying that your shoulder moved forward 80 thou? Sounds like it isn't exclusive to the 470 NE. Glad posting my failings could save you some brass Jeff.

Camster.......2nd reload, third firing, Because the pressures are relatively low I was able to pop them out with my pocket knife, no problem there.
 
wasrupzuk said:
I don't know everything, yet, and I get that the brass flowed from the web to the point that the cartridge case separated but where did it go?
Is the neck thicker or is there a pile of trimming shavings on the floor, or?
Click to expand...


As I stated earlier, I had to trim after every firing, which should have clued me in if I'd been paying attention. So yep the brass ended up on the table under my trimmer............
 
wasrupzuk said:
I don't know everything, yet, and I get that the brass flowed from the web to the point that the cartridge case separated but where did it go?
Is the neck thicker or is there a pile of trimming shavings on the floor, or?
Click to expand...

"Repeated full length resizing will keep lengthening the case until it must eventually be trimmed, possibly after only three or four rounds. The reasons for this are simple. The case body expands on firing; and its diameter is reduced in full length resizing. The brass displaced must go somewhere - and it does; it is pushed upward to lengthen the case."

http://www.hornady.com/ballistics-resource/internal
 
Well I do understand and have a Decent understanding of your experienced malfunctions. Case separation and the Resulting high-pressure gas releases must have been unnerving . But from what I now gather this happened multiple times . As for jewelry may be have them linked together as a bracelet. Or just nail them to your reloading bench as remberence ! Happily no injury was Ensued ( other than to your ego ) live and learn .:cheers:
 
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