Cartridge exploded in chamber
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I can do it this evening, need to know COAL.
Webley No.5
CGN Regular
- Location
- Rural Alberta/Calgary
Couple of things to add
1. Seating depth, you mention you are 0.030in off the lands, are you sure? Are you confident in your methods of measuring that? Also you mention it’s possible you loaded a 75gr instead, is it possible for that bullet to be on the lands at your seating depth? One study I saw posted that there was an 18% increase in pressure when seating on the lands and I believe that was in a 223 or 5.56.
2. If you go to vihtavuori.com their max load of n133 for a 69gr Sierra HPBT is 22.8gr, their max load for a 75gr Berger VLD is 21.9gr.
But more interestingly, the n133 is the lowest velocity for the 75gr and not listed in a lot of of other 75gr projectiles, to me that suggests it’s burning on the fast side and spiking early for the larger projectiles, I can also see a bullet touching the lands exacerbating the issue.
Now I usually a prescribe to the simplest theory is usually the right one, which means one of those errors is likely but a combination is not. However, just for a moment let’s say you overloaded the case, easy enough mistake to make but I’ll agree not likely to cause this level of drama but what if you overloaded the case enough to cause say 0.030in (or slightly more) of compression on seating and as a result the bullet pushed out 0.030in over night (did you re measure the COAL before shooting by chance?). This could mean that one simple mistake resulted in two issues. Obviously this is just speculation/thought exercise. Do you have any of the reloads left that you can check their COAL and powder load for interests sake?
Edit:
Above post wasn’t there when I was writing this, but if it was in fact 92K psi that is definitely enough to do much more then this on its own.
1. Seating depth, you mention you are 0.030in off the lands, are you sure? Are you confident in your methods of measuring that? Also you mention it’s possible you loaded a 75gr instead, is it possible for that bullet to be on the lands at your seating depth? One study I saw posted that there was an 18% increase in pressure when seating on the lands and I believe that was in a 223 or 5.56.
2. If you go to vihtavuori.com their max load of n133 for a 69gr Sierra HPBT is 22.8gr, their max load for a 75gr Berger VLD is 21.9gr.
But more interestingly, the n133 is the lowest velocity for the 75gr and not listed in a lot of of other 75gr projectiles, to me that suggests it’s burning on the fast side and spiking early for the larger projectiles, I can also see a bullet touching the lands exacerbating the issue.
Now I usually a prescribe to the simplest theory is usually the right one, which means one of those errors is likely but a combination is not. However, just for a moment let’s say you overloaded the case, easy enough mistake to make but I’ll agree not likely to cause this level of drama but what if you overloaded the case enough to cause say 0.030in (or slightly more) of compression on seating and as a result the bullet pushed out 0.030in over night (did you re measure the COAL before shooting by chance?). This could mean that one simple mistake resulted in two issues. Obviously this is just speculation/thought exercise. Do you have any of the reloads left that you can check their COAL and powder load for interests sake?
Edit:
Above post wasn’t there when I was writing this, but if it was in fact 92K psi that is definitely enough to do much more then this on its own.
Last edited:
Ya you can put 26 in and it is just around the shoulder.i vibrated after with a toothbrush.i am almost positive it was not the 75 but was the 69.but it could happen.as for touching the lands I believe it is 2.98(my paper is downstairs and my knees had a day in them already lol)and I loaded it to 2.78.am I 100% sure no but it loaded smoothly and no effort needed to close bolt.when it is tight or near tight on the lands I can feel it.
I'm using Gordon's Reloading tool. It's definitely showing much different results than Quickload. As I mentioned I have zero experience with VV powders but GRT has been pretty accurate in my short time with it.
Yes I really did a poor job of understanding what you had posted. I think we found the issue.
TheNatural21
CGN Regular
- Location
- Fort Nelson, BC
I'm also using Gordon's Reloading Tool. At 2.26" OAL even 22grains of N133 comes out as over pressure so that could be nasty with any more in there. I'm also seeing that would be a compressed load and a -very- compressed load with more powder.
f you're loading to 2.78 OAL and not jamming them into the lands (which I think I saw when skimming) then 22 grains of N133 with a 69 TMK should be quite a safe load, only 43k psi (disclaimer that it varies a lot with specific brass and chamber dimensions that I don't have, this is just using defaults). An extra 2 grains for a total of 24 is still only 55k psi.
Can you load them that long in a Tikka? it seems very long but I don't know much about 223's. As you can see, seating depth can make a very big difference.
f you're loading to 2.78 OAL and not jamming them into the lands (which I think I saw when skimming) then 22 grains of N133 with a 69 TMK should be quite a safe load, only 43k psi (disclaimer that it varies a lot with specific brass and chamber dimensions that I don't have, this is just using defaults). An extra 2 grains for a total of 24 is still only 55k psi.
Can you load them that long in a Tikka? it seems very long but I don't know much about 223's. As you can see, seating depth can make a very big difference.
Interesting thread. The jumps in pressure between 22 gr and 24 gr and 26 gr is dramatic in the small 223 case. When you look at it percentage-wise from 22 to 26 gr is not quite 20%, but the pressure increase is almost 50%, so it's far from linear.
It'd be interesting to know what the results of a 20% overload would be in a larger case, like a 308.
My experience with Vihtavuori is admittedly limited to N150, but I consider it to be a relatively high energy powder. IE the same amount of energy for a lower volume and charge weight compared to powders like H414 and H4350.
It'd be interesting to know what the results of a 20% overload would be in a larger case, like a 308.
My experience with Vihtavuori is admittedly limited to N150, but I consider it to be a relatively high energy powder. IE the same amount of energy for a lower volume and charge weight compared to powders like H414 and H4350.
There is nothing wrong with an electronic scale if you verify your calibration and keep it away from drafts.
I have the large RCBS check weight set and use it every time I am loading.
I'm not sure were I said I know how much was put in,if you read what I said about fan blowing on scale when zeroing, I said my goal was 22.1 but have no idea how much went in,but 26 gr was very doable. But I have no way of knowing.it could of been any amount.and I vibrate all my loads.that is the varget way.as for the second cartridge it was less then 22.1.again fan playing tricks.
