Neck Clearance - 6mm PPC
Tom Rollins
I turn to get .0005 all the way around or .001 in all of a loaded round. I know
that's pretty tight but sure makes the brass last a hell of a long time and both
rifles seem to like it. I don't have to size the necks down a lot to get a good
hold on the bullet that way either. One of my rifles likes not so tight neck
tension (around .001 tension) while the other likes it semi-tight (.002
tension). Neither rifles likes the tension to be much more than a .002 tension
for some reason. I don't know why but Clay Spencer said his rifles are the same
way, some like it semi-tight to tight while some like it a lot less. I have a
friend up here that turns for .00025 per side on clearance on his loaded rounds.
He never has to neck size his brass as it automatically springs back enough to
hold a bullet after each shot. All he does is clean the outside and inside of
his necks, reprimes, adds his powder and tops it off with a bullet seated out
too far thus letting the lands seat the bullet back for him when he closes the
bolt. I would never do it that way but get this, he always seems to group in the
.1xx's. His method also takes half the time to do his reloading as people using
the usual BR method of reloading.
Daniel Lilja
My 6 PPC reamer has a .261" diameter neck and I turn my necks to a thickness of .0085" per side. This leaves me about .001" clearence between a loaded round and the chamber. Some shooters like a closer fit but this diameter has worked well for me.
Walt Berger
My reamer has a .262 neck. I turn brass to 8.8 and use a .259 sizing button.This
works very well for us with moly bullets. Our bullet has a .2434 pressure ring
and measures .2431 just ahead of the pressure ring.
Bart Sauter
With a .262 Chamber and I trim my Brass to 8.8. So with a 243.5 bullet that
gives me a little less then a thousands clearance. I use heavy neck tension 257.
Carbide Bushing.
Ray Wight
With a .262" chamber, my cases are cut to .0086" which gives me .0014" (.0007"
per side) clearance with a .2434 bullet (if everything goes as planned.) Then I
use a .259" button in the neck sizer which gives me fairly good tension (.0016"
squeeze.) Usually, I have the bullet stuck into the lands firmly leaving a
rectangular mark (1/2 high as wide.) That is my formula, which is derived from
Ron Hoehn, World Champion. It will be interesting to see what kind of consensus
there is on this subject, if any.
Ron Galbraith
I use Lapua .220 Russian brass ( doesn't everybody ) to fireform into 6PPC
cases. After necking up the Lapua and after the appropriate sizing, etc. I turn
the brass in three steps so that I get a loaded neck diameter of .2605 inches (
for a .262 chamber neck ). This leaves a total clearance of .0015 between the
neck and the chamber. The thickness of the neck walls at this point is about
.0085 but this varies with variations in the particular bullet ( or lot ) that
I'm using. I have not found any problems with small variations in bullet
diameter as long as the loaded round does not measure over .261. I don't want to
go over .261 as I don't feel there is any real advantage accuracy wise. The
disadvantages though would be too much of a bother. This includes increased time
making sure the necks are not thickening further, watching for burrs, etc. Not
worth it. As far as neck tension goes, I like to use a "medium" tension. I can
get this with a .259 bushing. As long as the bullets seat smoothly and with an
even feel I have had good luck. I don't feel comfortable with a tension that is
too loose as I am not confidant that the seating depth would remain constant
with handling, etc. I am planning on a stint with moly coated bullets so I think
that I will have to increase neck tension somewhat to counteract the affect the
moly will have on gripping the bullets. This will be a trial and error procedure
until I get the "feel" that I am used to. For the most part though, I think neck
tension is a function of the barrel you are using. Some barrels seem to like
more tension than others. I also believe neck tensions take on more significance
if you like to jump the bullets, as opposed to seating them into the lands. You
could spend a lot of time trying to find that sweet spot, but I believe other
variables, such as seating depth, bullet diameters, etc. are more worth
pursuing.
Mike Bryant
My 6 PPC use a .262 neck diameter on the reamer and .246 for my .22 Waldogs. I
use .002" clearance for a loaded round diameters of .260" and .244"
respectively. I use a .258 bushing in my neck die and then go to a .257 bushing
when the .258 won't hold the bullet. With the .22, I use a .242 and a .241
bushing.
Allen Arnette
I like .001 clearance on each side.I change my neck tension a lot from barrel to
barrel.I sometimes change tension to change pressure without changing powder
charge or seating depth.
Jerry Peckumn
I am relatively new to tight neck chambers and use loaded 6 PPC rounds measuring
.261 for a .263 neck.
Mickey Coleman
If there's anything I hate is for my collars to be too tight. I don't guess
you're asking about my shirts, are you?
I have three guns and each one has a different neck diameter due to when they
were built but, generally speaking, I try to have at least .001-.002 total
clearance (just to be safe and I don't think an extra thousandths clearance will
make any difference) on the gun I happen to be shooting. Another variable I
encounter is that my Pindell dies make a 'fat' bullet that mikes .2446 on the
pressure ring so I have to allow for that when I'm shooting those bullets. I'll
eventually retire those dies except for emergencies due to that very fact.
I like a firm grip on the bullet with the case neck (shooting the 'fat' bullets
means I have to have a special set of cases just for those bullets in order to
keep the same neck tension). I'll generally use a .257 bushing in my bump die
and by changing the neck thickness I can keep the same tension regardless of the
bullet I'm shooting.
Now that I've written all this down I see what a pain it is shooting the 'fat'
bullets and I'll probably quit for sure now that Roger Avery fixed my other die
(and he did a SUPER job on it).
Roger Haney
I SHOOT,NAW,I GET .002 EXPANSION AND I LIKE NECK TO BE ONLY TIGHT ENOUGH ,SO I
CAN SEAT BULLET WITH MY THUMB WITH LITTLE EFFORT.IN REALITY THAT = ABOUT 2
INCH/LBS.
IT REALY DEPENDS ON THE BRASS YOU ARE USING,IF NORMA ,YOU NEED LESS CLEARANCE IN
NECK AREA,BUT IF USING LAPUA WHICH IS HARDER,YOU NEED LESS CLEARANCE TO GET
PROPER SEAL,THE STUFF DON'T EXPAND GOOD. I USE A .262 NECK,AND I LIKE TO HAVE
LOADED ROUND TO MEASURE .2605 TO 2615 WITH LAPUA BRASS.
Bill Giel
6 PPC .262 neck, loaded round 0.261+, no more than 0.2615, all must be exactly
the same.
J. D. Denoff
We use a .001 or .0015 neck clearance. Neck tension depends on which powder we
use. H322 seems to work best with a medium too light tension. We Just recently
switched to Vit. 133, Took us awhile to find the right combination but a heavy
neck tension seems to be the best for V133.
Wilbur Harris
I like to have .001 clearance for the loaded round (.0005 each side. Any
deviation from this should be in the more clearance direction as the last thing
I want is to have trouble at a match with not enough clearance. The necks should
be consistent from case to case and if I experience differences I immediately
reduce neck tension as much as possible and still maintain a hold on the bullet
such that it cannot be casually moved with the fingers. If my cases feel
consistent, I like firm neck tension. Consistent necks are pure luxury for me as
I seldom achieve this feat.
John Whitley
I shoot for .0015 clearance . Neck tension depends on the gun and or powder.
Normally I shoot .001-.002 neck tension whichever the barrel or brass likes. But
I have found that N133 seems to like more tension (.003 grip).I get vertical
with not enough tension with N133. Also coated bullets seem to work better for
me with allot of tension and well into the lands.
Billy Stevens
I use Lapua brass and cut it to .0088 for a 6PPC with .262 neck which gives me
just under .001 clearance on bullets with a .2435 pressure ring. I don't run
into any problems if I keep the necks clean and occassionally check to ensure
that I maintain at least .0005 as the necks grow from the brass flowing forward
from firing. I only use a set of brass for about three matches and them trade
them in for some new ones. I shoot V133 powder with the PPC and like to use a
.257 button which will give a fairly heavy neck tension with the above setup.
For me, V133 will not shoot as well unless you have heavy neck tension.
Rich Griffin
There are many variables to the neck clearance in the chamber. First, I like
about 1 to 1.5 thousands of neck clearance, which allows me to turn the necks to
8 thousands with a .260 neck. I feel if you go too thin it works the neck too
much. We have been chambering with a 6BR reamer that Bill Downey has which we
have shortened to .100. So for this is working well. As for the neck tension, I
like my neck tension to be tight and I use a .257 bushing.
Glenn Newick
That's a good question. I feel that proper and consistent neck tension is one of
the important factors in shooting great aggregates. An additional question would
be how much bullet engagement do you like in the lands. The two absolute killers
are: Too much neck tension and too much land engagement (jam). The best rifle in
the world will shoot 1/2" without enough clearance to release the bullet. I
shoot a minimum of 1 thou. That's an actual 1 thou, not 1 thou less than the
listed neck dimension on the reamer. Many reamers seem to cut slightly larger
than listed. I think some of that might be related to the individual gunsmith's
technique. Another question for you. When shooting the 1 thou, I don't size
before seating a new bullet, just punch out the primer and reload. With more
than that, I never go past two thou. If using that clearance I size with a neck-sizer.
For preferred neck tension, I find that the minimum neck-tension that will
securely hold the bullet seems to give the best groups.