Accuracy of new versus once fired brass

[msnations]

turned necks? tight chambers? we're talking about an AR right? what kind of group sizes are you getting at present?

-Mark

 

[Viperdoc]

Back to the beginning, I have a 7.7 twist Krieger barreled AR with a Geissele match trigger and Nightforce 6-32 NSX. I can shoot Sierra 77 MK pretty consistently at around 6.

I would like to work some varmint loads using bullets in the range of 50-64gr, but was wondering whether the 7.7 twist was too fast for these bullets.

Have new and 1x Lapua brass, CCI primers, and H335, TAC, H4895, as well as Varget and AA250. Brss prep included full length resizing, neck turning, chamfering and trimming. Tried Hornady Vmaxes, but they shot over an inch, no matter the powder or load. Have some Bergers and Sierras in this range to try as well, but was looking for some recommendations from others who have gotten these lighter bullets to shoot well in a 7.7 twist.

This means five shot groups at .5 or better out of a magazine in an AR.

 

[bozo699]

Viperdoc,
Sorry we got off topic. I have a friend with a 7.7 I know when not competing he shoots 68 grain barts and bergers but I am not sure if he shoots lighter than that. I will ask and get back to you.
Wayne.

 

[msnations]

With my 7.7s I've gone down into the 60 grainers with no problem. Never tried anything in the 50 though. Best results with sierra 69s but that's probably not ideal for your purposes. I've shot tens of thousands of rounds out of my ARs XTC and IMO it'll be tough to get .5MOA consistently out of a magazine. For whatever reason I can't get magazine fed rounds to group as well as single fed.

-Mark

 

[artbosco]

Now I know why you here people using fire forming barrels. 150 rounds out of 50 brass just to get it ready for a match is a lot of wasted barrel life ??? not arguing or denying I know its just the way it is. Wayne.

A fire forming barrel is a necessity if you want to preserve as much accuracy as you can in your match barrel. The process is long and boring but if you want match ready brass it's worth the effort.