Neck Clearance - 6mm PPC
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.
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.
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.
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.
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.
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.
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.
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.
I am relatively new to tight neck chambers and use loaded 6 PPC rounds measuring .261 for a .263 neck.
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).
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.
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.
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.
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.
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.
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.
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.