Re: 260 Brass made from unobtanium?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wchartz</div><div class="ubbcode-body">I just finished working up a load for my 260. Started with Lapua brass and several bullets. The best load turned out to be 139 Lapua, 42.6/H4350 Federal 210M. This combo gives me (4) 5 shot aggregate of.26 MOA. I then tried substituting new Winchester 7-08 necked down. Winchester has more internal capacity so I tried half grain more powder to equal velocity in Lapua brass.Groups went from .26 MOA to over 1 MOA. The Winchester brass had the flash holes reamed and the necks chamfered. The primer pockets seemed uniform and primers seated good by feel. I did not think changing brass would make such a difference. </div></div>
I have found that with H4350 it takes between .8 and 1 gr in resized Win. 7-08 brass to equal a given load in Lapua brass. Water weight is Lapua: 54 gr, Win 7-08: 55 gr. Both will shoot between .25 and .3 MOA at their best at 750 yds. My tightest vertical to date was with the Winchester. YMMV.
I also found two things that kept my Win. brass from being "great".
Neck tension. I don't know if Winchester work hardens their brass after annealing or just under-anneals, but their brass always seems to benefit from annealing. My 300WM would not shoot until I annealed their brass. The 7-08 brass just got it out of the box without even checking it.
Neck thickness. Both my 300WM and 7-08 brass had horribly inconsistent neck wall thickness. When using a bushing neck die, this places the bullet off axis with the barrel. Once turned and annealed, both shoot match quality. I anneal all of my brass with each firing.
Last thing... I do sort my 7-08 brass into +-1 gr. lots of 50... the weight deviation is significantly larger than Lapua. I have NOT tested large weight differences for POI change, so I may just be anal retentive (may?
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John