nk turning 243 ai?

[243DH]

I have a 243ai rifle being built as i type, i plan to run lapua brass with h4831sc and 105 hybrids. This one will be a 28" rem varmint contour, first AI is a 24" lv. The lapua brass i just got, after expanding nks for a few dents, show rather inconsistent nk wall thickness. Several cases have anywhere from .0125-.016 thick nks, on the same case. Measured with a ball mic. Is it better to turn nks after fireforming or before? Thanks guys.

 

[mikecr]

Always better to turn right out of the box, while you hold good turning mandrel fit.
Your not changing neck length with this improvement so there is nothing to consider about that.
But I hope you had considered thickness before choosing your chamber reamer.

 

[243DH]

Well not sure on reamer spec as far as nk dia is concerned. My win brass is much more uniform, .014-.0145. I will use it when lapua brass is out. On the lapua i will just try to get to .013 as the thickest. It will be a repeater for tac matches so i don't want super thin nks that get damaged. Short of over working brass is there a real downside to having a slightly loose case nk to chamber fit? I have several rifles with standard or match no turn nks that i shoot nk turned bushing sized brass . They shoot dang good and get 12-20+ firings am i missing something ?

 

[mikecr]

I don't know anything about the reloading clearances you want.
But I don't turn necks without a plan that includes target clearances.

I'm just sayin you might think about it.

 

[243DH]

Not sure about too much clearence, my main concern was about a case that had .004" variation in the nk thickness. That equals inconsistent nk tension and runout. Those are bigger issues then "target clearance". This rifle will get run in some nasty conditions, way worse then anything at a br match. I don't care for, or want a chamber that has .001" clearance in the nk. That would become zero in the fine dust elements and conditions that the rifle will be used in. Like i said in op junk lapua brass is my reason for turning, not some off the wall reamer print.

 

[stacy]

NEED TO BE SURE OF THE NECK DIA.BEFORE U START YOUR TURNING LIKE ALL READY BEEN SAID BOTH OF MY 243ACKLEY'S HAVE .270 NECKS SO MY BRASS TURNED TO .012.5 X2=25+.243dia bullet=.268 so I HAVE .002 CLEARANCE.

 

[mikecr]

When I said 'target clearance' I meant and should have said 'desired clearance'.
If you want to go high in clearances, that's fine too, but nothing is free. The greater your sizing the more energy you're adding to necks, and the greater your tension will vary between load cycles. So if you decide to keep your muddy brass around a while, prepare to anneal frequently, and with a really good annealer to do it.

Oh,, whether your reamer print is on or off the wall, you might want to look at it. Could answer really basic questions for you.

 

[243DH]

Its a standard ptg with freebore set for 105, meaning not tight nk. Not really muddy brass but there is a reason stiller makes a tac action and br action. I was more concerned with variation nk tension caused by brass that had irregular nk thickness and runout. In my head those are worse then a few thou springback work hardening brass. Runout would be noticed out of the gate, whereas work hardening would take multiple cycles(10+firings) to show up. Thanks for the info on nk length.