lapua brass/neck to chamber neck clearance, jack neary....

[jayjaytuner]

I saw a video from 2010, it was Jack Neary talking about load tuning etc....
anyhow, he stated that when in relation to the chamber, at the neck a loaded round with around .002 or .0025 of clearance should be more accurate than .001, or a half thousandths measured at the pressure ring...at the neck chamber clearance.

he was refering to a .260 at the time, said he heard it from bil forester "realating to brass-cut thin to win"
which at the time hes chambers neck was .262....so he turned the necks to achieve .002 or slightly more clearance.
he then rechambered with a .263 neck, and his loaded rounds were measuring .2602....

basically he says that little extra clearance is not a bad thing,

so with that said, im wondering if the same thoguht of mind goes to different calibers?
im getting ready to order a 6 dasher reamer.... with the new blue box lapua brass loaded rounds are mearuring right at .2675 to .268, so im thinking a .2705 neck or .271 would be the way to go??

any thoughts on this...
jay

 

[Chuckhunter]

Jay, I have had the same experience as Jack. I used to shoot a 6PPC back in the day when it was allowed in the Hunter Class and at first I shot a fitted neck which shot well but not for long, I then turned for .001 clearance and they didn't shoot as well, returned them to have .003 and they shot terrific. Found the same to be true with my 30X44 and over the years I have personally come to the conclusion that I would rather have a little extra clearance than not enough. Within reason of course.

 

[Steve Wilson]

This is the link to Jack Neary's presentation at the Super Shoot, I believe from last year. There are 6 parts to it, this one is the first. http://www.youtube.com/watch?v=7SZWvn68bRU

Part 6 is mislabled on You Tube, here is the correct link. http://www.youtube.com/watch?v=ILvH6TYNcx8&feature=channel&list=UL

I found several of his points to be in direct contradiction to what has been preached for years. Downright blasphemy. As you mentioned, he wants more neck clearance. He also said that in a 6 PPC using VV 135 that you need more neck tension.....like .005 I think. One of the biggest surprises was when he said he wants .050 between the end of the case mouth and the end of the chamber. I had to play that part over again.....did he just say .050? Yup.

The You Tube presentation isn't professionally filmed, just some guy recording it. It takes about 1 1/2 hours to watch all six of them but is well worth the time. He is coming to our range to give the presentation during the East-West tournament later this year. I plan on attending it.

 

[david12601]

Curling mixed results

 

[Dusty Stevens]

Its like neck sizing, nobody has shot good with what everybody calls the “standard .001 or .0005” clearance in over 25yrs- back when a .350agg was a good one. This is one reason most shoot a .268 or bigger neck, so you can turn them thin to win but still have enough neck to be able to run extreme neck tension. You ever seen the “wasp waist” on pistol cases?