Re: How many reloads become unsafe?
19D,
If you're concerned about this (and it's perfectly reasonable to have such questions), there's several ways to check the status of the brass. Some are sacrificial, and will cost you the brass, others will not. Looking at the outside of the brass will usually give you plenty of warning as to a pending head separation, if you know what to look for. In this instance, it's a discolored or roughened section of brass, right around the point that the pic posted here shows the splits. Unless something is way out of kilter on the headspace (either your sizing or the chamber), this discoloration will show up plainly before you lose the case. Toss it at that point. You can also check this with a bent paper clip with a point sharpened on the end. Using a fine file, sharpen a small point on one end of a paper clip that you've straightened out. Put a 90 degree bend about 1/8" ahead of the point. You can now insert the wire into the case, and using the sharpened tip, drag it along inner wall of the case. If the case is thinning (stretching), you'll feel the tip when it traverses the weakend area. Again, if that dip is present, it's time to toss the brass, even if the discoloration hasn't appeared on the outside of the case. This is truly a sistuation where you're better off safe than sorry. Brass doesn't cost that much, and it's always better to err on the side of safety.
The last method entails simply looking at the brass and seeing if the thinning is developing. This can be destructive if you section the case, or not, if you have a borescope. Actually, my own borescopes probably see as much use in this respect as they do checking out the actual rifled barrel. Insert the scope in the case, and simply see if the case is stretching. If it is, you'll see it plain as day. Lacking a bore scope,now you're getting into destructive methods; sectioning the case. Simply use a hack saw to cut the case lengthwise from the head up into the body section, and see what the inside looks like. Again, if there's a thinned section, you'll see it very plainly.
As I mentioned in an earlier post, much of this depends on what you're loading for. You're dealing with a very strong action, that won't allow for a great deal of flex. Keep you're sizing (bumping the shoulder) to a minimum, avoid working the necks more than you need to by using an appropriately sized bushing, and you're halfway home. The real key is to simply avoid the stupid pressures. when I hear guys complaining that primer pockets are loosening after one or two firings, I'll bet money right then and there that their loads are well over what they should be. Lot of factors involved here, but that's a biggie.
With some other action types (I already mentioned the M1 and M14 family) short case life is simply the cost of addmission. In these rifles, three firings, period, end of story, time to quit even if the brass "looks" fine. All depends on what you're doing, and you're already asking all the right questions.