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Hello all,
I recently had a barrel chambered in .358 WSSM and fitted and headspaced to a savage action. The next step was to fireform some brass but in doing so I noticed the primers were standing proud in the fireformed cases. This made me concerned about excessive headspace. As I don't have the proper headspace gauges, I placed masking tape on a factory new case and inserted it. It took four thicknesses of tape before I felt resistance on closing the bolt. The total tape thickness was about .010 thick. I could probably force it closed with even an additional layer of tape so approx. .012-.013. I realize this is a pretty open chamber which puzzled me as the gunsmith has an excellent reputation. Then I realized that I had sent along a "dummy round", which was a .358 WSSM round which had been formed in the chamber of my brother's AR-15. It fits quite snug. So I screwed up. I know I could have a smith re-set headspace on the barrel but deer season is fast approaching and I don't have the time to do this. If I fireform cases without the ejector in place they look OK. So my question is this, CAN I JUST GO AHEAD AND FIREFORM CASES LIKE THIS AS LONG AS THE RESULTING CASES HEADSPACE OK? And HOW excessive is the headspace in this chamber? What's normal? One gunsmith told to just go ahead and load some rounds and they would "fill out" with the first firing and that the small amount of excess headspace would not be enough to damge the cases or cause head seperation. Does that sound right? Thanks for your help.
 

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This is not really a reloading area but I'll give this a go. First masking tape testing for headspace is not a good idea.. the results are not really valid as the brass case will move from the camming force of the rifle action.. The cases you fireformed that had a protruding primer may have not completely fireformed. When a case is fireformed the case is driven into the chamber by the firing pins blow until stopped by the cartridges shoulder. As the primer fires and pressure builds the neck and then the shoulder area will obturate and lock up in the chamber. At some point the pressure will stretch the case rearward until the case head is stopped by the bolt face. The stretching takes place in the aaea of the case just ahead of the web of the case( in front of the belt if belted). As long as this isn't repeated or is not excessive the case will be fine.. Assuming a standard reamer/guage set was used to chamber the rifle it should be within the tolerances specified for the round. You didn't give the load and methodology used to fireform but assumeing that's OK you should be fine. Since the primer was protruding the case didn't fully fireform or the primer would have been reseated in it's pocket as the case stretched to the rear. So perhaps a slightly hotter fireforming load would generate the pressure required..? Was a custom reamer ground from the dummy round you sent the smith? If not then it may have been used only as a gjuide to cutting the throat (leade) for the chamber. There are too many questions to give a definitive answer to your question but an overlength chamber can be used successfully by simply setting the sizer dies to NOT set that should back at each resizing.. Thus the cases will last as long as nearly any others. I don't know the process used but simply not pushing the shoulder to the rar as far should tighten the headspace for your fireforming task and a hot enough load should leave the primers flush with the case head. The ejector seems to have been just enough resistance to keep the case forward and keep it from engulfing the primer! You should be OK buy simply increasing slightly the load used.. Sorry for the rambling reply but it's late and I'm a little tired.. Good luck with the hunting.
 

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Good luck with the new rifle..!
 
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