Good day
I hope someone here reloads the 375JDJ and can help me.
I just bought this barrel used a little over a year ago and am having difficulty
making my brass last. I'm only getting about three loadings from my brass and
then I start getting head separations. My loads are accurate, the shells insert
easily and they extract easily also. The only problem is they start breaking off
about a quarter of an inch from the rim after about three loadings.
I should get more loadings than that shouldn't I??????????
Thanks
Mike

PS I'll be posting this on the reloading site also

(here too) Sounds like you dies are adjusted wrong and your setting the shoulder back when you resize, causing a headspace problem, and over worked cases.

Form new brass... back off the die, adjust it down ever so slightly, trying the case in the gun as you go, until you can get the gun to close and lock up.

Then refine your technique by using a feeler guage set to determine what the actual barrel to frame measurement is, the adjust the die so that there will be about .001" clearance between the case head and the breech face when the barrel is closed, but no more than this.

If you cannot measure exactly how far cases protrude from the end of the barrel, then try to close the barrel on a sized case with the thinnest feeler guage you have in the set, which should be about .0015." If you don't have one that thin, get a set that does go that thin. They are probably less than $10, but that $10 and some measuring is a whole lot cheaper than $30-35/C brass that goes south in just a few loadings.

Take a look also at the degree of bulging at the point where they separate. I shoot for a diameter at this point not exceeding .468-.469." The final choice of diameter depends largely on what the size dies will size to. If they do not size, for example, smaller than .469" at this point, I may have to open a chamber to .470" to create the needed size difference. But then, once fired, the owner will only be working the brass about .001."

Compare the diameter of your sized cases and fired cases to see just how much the brass is being worked. If it is more than about .003" then consider a different set of dies more closely matched to your chamber.

Mike

I have 4 SSK barrels in calibers based on the 444 marlin. The one thing I noticed with my 375 JDJ was the rim counter bore was extremely deep (quite a bit deeper than the rim thickness). Since this case, in my opinion should headspace from the rim, I called Mr. Jones. He was his typical kind self and explained that he did in fact cut the rim C/B deeper than required if headspacing off of the rim only. I asked no more questions and measured my other three barrels. All the rim C/B's were exactly the same depth (within 3 decimal places). The reason for the long story, I had some of the same problems with my 375 JDJ and thought I had discovered a problem with SSK barrels. As usual, I was incorrect and the problem was all my doing. I suppose he does this to eliminate folks like me from double headspacing. After I adjusted the sizing die correctly (took some advice from Bellm website), my brass now lasts almost indefinitely and accuracy from a couple of barrels are nothing short of outstanding. I would offer some loads but I live in the desert of the southwest and what works here may not be optimum for your location. Hope this helps ya.

1buba, wanna archive the post above?

Mike