Home Forums Hunting & Shooting Ask The Gunwriters Headspace issue?

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I am loading for a friends rifle, 6-284. I am using necked down 6.5-284 brass from Norma that I purchased new. First testing was with 75 gr. V-max and H4350. Worked up using Hodgdon's data from 49gr., stopping at 51.5gr. at 3600fps. Didn't notice anything out of the ordinary untill measuring brass afterward. Using the Hornady tool, the shoulders on fired brass measure .020" longer than new brass. Have only been reloading a couple of years but this gives me pause. The rest of the guns I have loaded for have shown .005" growth or less from new brass. Case head separations don't sound fun. I have used the bent paper clip trick to feel around and dont notice anything but don't really know what an incipient separation would feel like. Visual inspection of the inside of the case doesn't raise any suspicions either. 

What do you guys think? Would I be safe to proceed as long as I dont set the shoulders back more than a couple thou, or is one time stretching of the brass by this much enough to compromise it to the point I should abandon the project? Any advice is much appreciated, I can provide more detail if it would be helpful. Thanks

I would size to 6mm with a false shoulder and not set back the case shoulder. A one time forming should not be an issue but still I would be cautious and section a case just to see. If you have incipient head separation the paper clip will usually make this obvious.The 6.5x284 Norma/Winchester differences could be a factor. Neck size for the second firing and then set the dies to the new neck/shoulder length. The idea is to work the brass the least possible amount and you won't 'splode anything.

Myself, I would necksize only on the once fired brass and if it chambers easily I'd take that as a hint the chamber is that much longer than your original necked down brass. Redding has suggested neck sizing only and firing the same case three times to give a case for setting their Instant Indicator tooling - strongly suggested but Wilson and Forster and others do as good a job if not IMHO so conveniently - and such.

I have found that stretch marks show up on the outside and can be readily felt with a hook and seen with a bore scope. Sectioning a case with stretch marks and finding the weak spot is a guide to feeling for the internal groove. I wouldn't throw the first fired cases away but I would start over with fresh cases. First establishing a feel for actual chamber length by neck sizing and firing a case 3 times I would then form cases to fit the actual chamber and not a paper diagram.

If a custom chamber I'd ask what reamer and try go, no go and field from the same brand if possible and if the chamber is long I'd treat it as a wildcat. Either forming cases with a filler or a secondary neck or whatever suited me. I might not go to this much trouble for a friend's rifle. Then again if I had a suspect chamber I might avoid using even a good friend's reloads.