In the larger calibers, what neck clearance has worked the best?

B

Boyd Allen

Active member
Recently, on another board, there has been some discussion loaded round of neck clearance. It has been my impression that some of the successful 1,000 yard shooters, who shoot .30 cal., prefer as much as .005 total loaded round to chamber neck clearance, for a cleaner bullet release. Is this the case? What have your experiences been? Thanks
Boyd
 
I use .0015 to .002 total clearance. Not saying that is right, but works for me. I have no trouble with vertical -- except when shooting over the high firing-position berms at ranges set up for 100 to 1,000 yard highpower.
 
Boyd

I would not call myself a 1000 yard 30 cal. shooter, so if that's who you need to answer your question, then I am not the one. On this forum, I almost wonder if speaking of looser neck clearance is akin to sacrilege.

I am also interested in opinions on this issue of neck clearance as lately I have been running looser rather than tighter on neck clearance and feel the results have been better.

A number of years ago I shot 7mm's at 1000 yards and I was very careful to keep a tighter neck clearance (turned the necks on the brass to be .0025" under the chamber when loaded) but every so often I would see a high shot at 12:00 o'clock, and if so, I would hold aside the brass case and check it out (was there an anomaly I could detect, thickening of the neck metal, donut forming, etc.). I typically never found anything. I just set up a 7mm RSAUM a couple weeks ago for long range shooting and when I used some brass with .0025" neck clearance, again I noticed unexplained vertical now and again. I then turned a batch with .004" neck clearance, the vertical seems to have gone away entirely so I am running with that.

In a .308 Win Palma barrel I have, I have been running .005" neck clearance and have found it working out very well for consistency, yet when I got down under .003" clearance with other brass in the same rifle, things seemed to get finicky and I felt I saw more errant shots and vertical.

Certainly none of what I did would qualify as "scientific testing", but I feel I was never prejudiced by running a little extra neck clearance, but the reverse has not always been true.

Robert
 
Recently, I have watched Youtube videos of Jack Neary's presentation that includes the topic of neck clearance. Based on what he, and other very successful shooters have told me about what they are using, I am changing my 6PPC brass neck thickness to give a clearance in the area of .0025 to .003, depending on the bullet diameter.

I know someone who is working on a .338 Lapua, and having read of someone getting better results with a .30 magnum bench rifle with .005 clearance, thought that he might be better off with more clearance, for a better bullet release, rather than concentrating so much on trying to control bullet alignment by running tighter.

Charles, are you annealing? Could it be that this allows better release with less clearance?

Boyd
 
Boyd,

I plan to get around to annealing my necks real soon now. I even bought an extremely precise annealer from 4Mesh (Phil Bowers).

I do everything wrong. I use a long neck. According to Bobby Hart, when developing the .30 Hart, he preferred short necks because they "release the bullet better." Mine's longer than a resize bushing.

I use .001 freebore diameter. Current fashion, I believe, is to keep the freebore diameter just a whisker over bullet diameter -- but my reamers are set up for .309 in my 30s..

I don't use a lot on neck tension. Can't seat the bullet by thimb pressure, but it isn't great.

* * *

I've watched targets over a year-long period. Guys that do this or that to "reduce vertical" always have some occasionally. "Oh," they say "that's conditions." And I agree. I get the same thing with my tight necks.

Maybe it is different at short range. Tony Boyer use to use .0005 total clearance, back in the '90s. Has he changed his mind?

* * *

But I also don't think more clearance hurts. Maybe when I make up a new set of cases, I'll use more.
 
Charles E said:
I use .001 freebore diameter. Current fashion, I believe, is to keep the freebore diameter just a whisker over bullet diameter -- but my reamers are set up for .309 in my 30s.
Click to expand...

I think this is a good idea. I've been doing some extensive testing with a 6.5mm wildcat, and I discovered (by accident) that a freebore approximately .0008" over nominal bullet diameter gives lower standard deviation than .0003".
 
When I was new to long range I was cautioned to use plenty of neck clearance (0.003" total) to avoid vertical, Believing that I could manage closer tolerances and gain some precision I tightened up and was quickly persuaded otherwise. I've been using 1% of bullet diameter (3 thou for 30, 2 1/2 for 6mm, etc) as nominal clearance with good results but wonder if more clearance would be better yet. Maybe 1% should be a minimum.

Greg
 
I tried tight necks but I got away from that in a big hurry. Several times then when I'd make new brass, I'd make sets up tight so I could see again how that works (thinking perhaps theres more to it than I was seeing the first time). I was reassured each time that going to very tight bullet release wasn't in my best interest. I'm sure it's related to other things you do in your reloading process. Some shooters run very close necks and shoot extremely well. No doubt about it. I'm not one of em.

I think for a lot of clearance to work, annealing is a must on every firing. jmo. But then I believe then a lot of other casework issues go away on their own. It's just less hassle to shoot consistent.

As to throats, I think a overly loose sammi throat is too loose, and a really tight one is too tight. For all I know it may vary with caliber and bullet weight. I don't know. I tended to stay fairly close on that, but at the same time I'd jump the bullets 100. So who knows what combination works...
 
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