Too Much Pressure??
 

I have loaded for a couple different 300 whisper rifles that I have but I just built a new one on a savage action. Today was the first day Ive had it at the range and the first time I pulled the trigger the round went down range and the case is stuck in the chamber. When I got it home I used the cleaning rod to pop the case out (hardly any pressure). The case is black on the bottom and you can't even read the head stamp. The primer is not blown out or pierced. I look at the side of the case and there is a small crack just above the rim that goes about halfway around the case. The brass is once fired LC 223 brass that I formed and had never been fired in a whisper. Is this pressure signs or just weak brass???

What load are you using?

I have had a few pieces of LC and Privi brass that split just above the rim as you describe. They had been loaded once or twice, plus having been fired once as a 5.56 round.

None of these were "high pressure" loadings.

I was shooting 18 gr of H110 with a 150 gr FMJ. I have never had pressure problems with this load before. Its hot but not that hot.

I've shot 17.8 gr. of H110 with a 150 gr. Sierra soft point (.30-30 bullets) with no issues.

Like I said, I've seen it before. I don't know if working the cases to form them makes them that much more brittle.

So far, I've just kept an eye on them.

I'm new to 300/.221 and was looking for working loads.
It looks to me that load published on internet kind of unsafe? or what I'm missing? The QuickLoad software is accurate and used by comapanies like Berger to calculate loads.
http://www.freeimagehosting.net/uploads/d825073cc6.jpg

First I'd like to make it clear - I'm new to Whisper, but have experience loading in supersonic for BR target and subsonic for fun in .308
So I use QuickLoad 3.2 to develop loads and my experience is that this software is very good.
I'm finishing my first custom rifle and wanted to make some supersonic loads to form brass.
To my surprise all published supersonic loads producing significant overpressure that is very unsafe according to QuickLoad.
So my question is what am I missing?
here is QC screen
http://www.freeimagehosting.net/uploads/5e5d0d942c.jpg

With VV-N110, which looks to be very similar to H110, I can't get any pressure signs with a 125 gr. bullet, period. The most powder I've felt comfortable stuffing in there is 18 grains, and even then, it gets compressed a bit by the bullet. This is in a Savage action with a Shilen barrel. I may try some 150 grain bullets one of these days, but I still think it would be hard to rupture a case like that, unless there was something already wrong with the case. Personally, I'd reduce the charge a bit and work up from there just to be safe.
-Dan

I'm no expert on the subject either, but 55kPSI is within the .223rem SAAMI specs, (well at the max, but within the 5.56 specs) so if youre using cut down .223 brass, I'd see no reason the brass couldnt handle the pressure. The chamber/head area on the rifle is the same as .223, and unless you have a thin spot in the barrel from the bore being .308 instead of .224. So other then a thin spot in the barrel profiles I dont see why 55k PSI would be unreasonable.

I wonder who speced the max pressure for .300-221 in quickload.