necktension vs fl/ns

[Drolds72]

I did not want to hijack the necktension thread or the FL vs NS thread, but I had the same tension problems with my 22-250. In my situation, I had failed to realize that the cases had grown beyond spec length and I was throwing some crazy groups 3-4", instead of the sub.5" groups I can usually get.
I have always necksized, but recently picked up a FL die to process some of the range brass I have been finding. My question is, would bumping MY brass back .001 with the FL die slow down or prevent the cases from getting longer? Or should I just stick to necksizing my fireformed brass (and checking length more often) and save the FL die for range brass...
As a side note, when my cases were too long, I could not even start a 53g vmax boatail in the case. After trimming and shooting, bullets dropped clean in or with just a touch of drag, but no "donut" that would prevent bullet from going all the way in.

 

[Dusty Stevens]

Fl size all your brass. Neck sizing is a technology that died back in the 50's and will eventually make you angry and have you chasing your tail

 

[LHSmith]

The problem with Neck Sizing is sooner or later you will have to Full Length size (unless always firing "start" loads). In the mean time every time you reload your case dimensions differ (volume changes) possibly changing POI and accuracy , you cause more wear on the bolt lugs, and eventually after alternating between FLS and NS the case dimension at the web gets to the point it will not be reduced any longer by the occasional FLS without going to a Ring Die .....and that will be another short -term fix. Not understanding about case length interfering with seated bullet COAL, other than you might have to chamfer the case mouth more in initial prep and after trim.
As far as range brass......I avoid it like the plague.....may be fine if you simply want to throw lead downrange, but as far as accuracy potential ---forget it not to mention it will probably play hell on your bolt lugs.

 

[Laurie]

It's not about your cases getting longer, ie the case OAL. That happens whichever sizing method you use, although FL sizing usually accelerates it a bit. It's about shoulder movement. In a bottlenecked case, especially a fairly steeply tapered one like the .22-250, a combination of internal pressure and a plug of still to be burned powder kernels being pushed against the shoulder walls under enormous pressure before the charge is all consumed, pushes the shoulder forwards.

Neck sized brass will often start to give slightly tight chambering on its first reload and get worse on each subsequent cycle, the rate and degree depending on various factors such as maximum pressures, case design, wall thickness, type of powder even and fill ratio, action strength and stretch. It doesn't do so consistently for every case though and you start to produce a major variable. The trick is to 'bump' the shoulder back so there's 0.001-0.002" clearance between the shoulder and chamber when each and every round is chambered and the bolt locked. FL sizing does this, but there are also bump dies. Forster makes a very useful Bushing-Bump NS + shoulder bump sizer, but only for a limited range of cartridges.

Many factory rifles perform better with FL sizing as it straightens / realigns the case body, many factory rifle chambers being otherwise and affecting anything fired in them. If you wrecked your groups by FL sizing, then that was doing something it oughtn't have. The most likely issue was setting the die at the 'default setting' hard on the shellholder plus a bit. This can push the shoulder back far too much creating excess headspace which does little for accuracy and also sees the case stretch on firing - ie the OAL grows. In any form of bump or FL sizing, the die should be set-up in the press using fired cases as an index and only bumping shoulders the minimum. There are ways of measuring all this, but that's another story and a bit too much work for a two-finger typist late on New Year's Eve (or 'Hogmany' as it's called in my native Scotland). There are other possible causes such as an out of true expander stem.

 

[Drolds72]

Ok- I think I got it. I actually have a .350 sized Headspace gauge, and just measured up some brass. recent necksized fired was 1.557, and some of the FL sized brass that I was playing with measured up 1.553 or so. I was doing it by feel with the bolt, so kinda close. If I am reading the info right, I should be targeting 1.556, and my accuracy should return and be more consistent. I did do a couple of pieces with die screwed down to shell holder, and that case measured 1.496! Also getting good at drilling and tapping stuck cases...now own a tin of imperial wax...