Sometimes we just might get caught up in,....You know here is the way this always works. Might be best not to have to many preconceived notions.Best rule is test, find the answer yourself.
ADJUSTING NECK TENSION
- Thread starter Bill Norris
- Start date
I do keep my face on the gun for every group. I remember when the 3rd shot disappeared into my same poa as the first two saying to myself, “don’t eff this up. You can stop now, but you’re not going to. Don’t eff it up!”
Reminds me of the lifesavers commercial, with dad and daughter sitting on the bench watching the sunset.. pretending he's making it set I suppose. It sets and after a few moments she says "Do it again Daddy!"
Hate it when I lose the recipe..
Jackie that light neck tension thing did not work for me in my 30 BR using .002" neck tension so I tried .003"(and .004"). That worked for about 3 or 4 loads on my brass( I fireform twice) and then I noticed the same dropped shots. I turned my brass to .010" leaving a .328" loaded diameter and viola with the old neck tension of .002" everything is consistent for up to 12 rounds. I think the thicker neck of .010" vs. the old of .0095" that I was using is keeping the brass spring back more consistent thus giving me better consistency on my neck tension. Hard to believe a difference of .0005" can actually help but every barrel is different.
That .002" clearance on my .330" chamber has got me thinking(like Tony) an extra .001" in a .331" chamber may be the way to go. The 6BR brass gets pretty thin stretching from .243" to .308" and can really affect brass springback and in my case annealing didn't help. I think that was what Tony was talking about in his book. Starting with a .263" chamber and using that same bushing for .002" tension and then turning the brass to leave a slightly thicker neck to achieve the same tension for a longer period of brass life. Hence the Speedy/Boyer reamer neck of .263". I'm shooting 30 UBR and I think it's a much tougher target for x count.
The way I understand Erik's video is if neck tension is an issue and you're on the weak side already then try more tension and of course if you're on the strong side you should try less tension. In my 50 years of reloading for competition I can't see the neck tension issue really making a big change. Tuning in a good load to make it a great load, yes of course! Combustion effect will be more likely affected by a change of powder type or the charge of powder.
I have Tony's book and have read the load development sections a few times. Tony's method always included testing with the same 3 different bushing, 3 different powder charges and 3 to 4 seating depths. If he couldn't get a rifle shooting to his satisfaction after going thru these combinations, he'd replace the barrel. I don't have that option, I will keep going until I find a combo that works for me. I will say, that I'm going to give his method a try (except for the barrel replacing part). Tony's accomplishments speak for themselves, IMHO.
I went down that road playing with neck tension using the Redding S Type bushing die set. Tried .001 and .002 neck tension also bushing dies can create another problem of excessive run-out . After all the playing around I found my standard RCBS F/L sizing die worked much better giving me .003 neck tension in most cases , I'm using thick brass , FC , ADI & HSM , using Rem. & Win. the brass is on the thin side my tension was.002. I don't neck turn my brass so I always use the expander ball , just lightly lube the inside or the case neck with a Q-Tip . If your neck turning your brass then you could do your sizing without the expander ball .No harm in playing with neck tension , didn't do much for me . Maybe if I always could shoot a one hole 5 shot group I may have saw a difference but I happy with a one ragged hole group using my Full Length Standard Die at .002 case headspace , .003 neck tension and .002 jump . Hope I Helped in some way.
Northridge
Gold $$ Contributor
In my humble opinion, the neck tension developing better SD or possibly a more affiance combustion is very possible as we record the Data, but I don't feel this is the complete story as to why one bushing or another will win out at any distance.
Shawn Williams
Shawn Williams
I think that if you sized a neck .004 under and seated a bullet, measure and pull the bullet, measure the case will not be .004 under. My experience is anything more than spring back is yield in the brass. My point is that if you bushing size a pc of brass .005 smaller than you need and them use a mandrel to finish size you end up with a pc of brass that is the size of your mandrel minus the spring back. I would believe that seating the bullet does the same thing. This would lend me to think that the whole effective range of tension is equal to the amount spring back before yield of the brass. Your annealing frequency and temperature consistency probably are the players here. I came to this conclusion on my loading bench when I was trying to figure bushing size for use of a mandrel and trying to not overwork the brass. Not on the target so flame away.
You are correct. There will be a point where decreasing case neck diameter will yield no more neck grip because the bullet itself will act as a mandrel to expand the neck to its diameter with uncertain final grip strength and the case neck is not really in tension. A cold bearing or bushing inserted with an interference fit will expand an be held in tension by the material around it. The case neck has no material surrounding it to resist the expansion and will simply stretch. Neck tension is somewhat of a misnomer since the case neck is not held in tension and utilizes only the springiness of the brass to grip the bullet.
Over the winter I played with neck tension. My rifles liked .0015-.002. It gave me better es sd numbers. While pulling some bullets I noticed huge differences in the force needed to pull bullets. I decided to try using Lee case lube inside my case necks to try and get more consistent bullet release. It showed in my numbers as they stayed in single digits. I also tried Redding dry lube but the lee seemed better. Has anyone tried this approach?
I see neck tension as a broad term that is dependent on more factors than interference fit. The objective is to control the internal ballistics in the case during firing to replicate the pressure curve consistently from shot to shot. The friction between the bullet and the neck is a factor which is dependent on the reloading process. Was the brass cleaned to base metal? If so, was a lubricant, such as Neolube, used to replace the carbon layer on the neck interior? The case neck preparation and sizing process has a lot of variations which we use. Were the necks turned? Was an expander ball used or just outside sizing? What about annealing? The key here is consistency within a given lot of reloaded cases. Consistency in the reloading process coupled with rigorous trial and error for each individual rifle system is the key. .and. the process that works in one rifle system may not work in another. I don't think there is a one size fits all answer, just best practices. Winning shooters have attention to detail and a relentless need to engage rigor.
Yes I have. I ultrasonic clean my brass and if I don't apply some type of lubricant the bullet seating operation will be very "grabby" for lack of a better term. Eight to 12 hours vibrating in corn cob media with Flitz Trumbler/Media Additive will deposit a fine coating of polish to the inside of the neck and make bullet seating nice and smooth. An added cosmetic benefit will be very shiny brass with even the annealing discoloration removed.
I'm curious about your bullet pulling comment as others have made similar comments. Logically, if it takes more force to pull a bullet than it took to seat it - something must have occurred within the loaded round to cause this. No doubt it would take far more pressure to push a hard to pull bullet out of the case than one seated with light neck grip. Some have referred to this phenomenon as "cold welding". Did you examine the bullets you pulled? Was there a discoloration on the bearing surface of the bullet? Most would never be aware of this huge increase in bullet release force because few have the need to pull bullets before they are fired. Seating the bullets to their desired seating depth just prior to shooting them will mitigate this issue.
Pull force is higher with disparity tied to amount of neck upsizing from bullet seating.
You know when bushing downsizing necks greater than ~5thou, the necks usually downsize a bit more than stamped on the bushing. This is due to the angle of sizing, causing a rolling overshoot.
Now think opposite for mandrel/bullet upsizing. High upsizing causes similar angular overshoot. This is a barreling(middle bulging) affect that reduces seating friction.
When pulling bullets the bulging is pulled taught, friction peaks, causing a chinese finger trap affect.
With no friction fiddling inside necks, just normal carbon layer, pull force never comes into play with bullet release. It's purely charge pressure expansion that normally releases bullets.
A very tiny percent of charge pressure that is way less than pull force.
You know when bushing downsizing necks greater than ~5thou, the necks usually downsize a bit more than stamped on the bushing. This is due to the angle of sizing, causing a rolling overshoot.
Now think opposite for mandrel/bullet upsizing. High upsizing causes similar angular overshoot. This is a barreling(middle bulging) affect that reduces seating friction.
When pulling bullets the bulging is pulled taught, friction peaks, causing a chinese finger trap affect.
With no friction fiddling inside necks, just normal carbon layer, pull force never comes into play with bullet release. It's purely charge pressure expansion that normally releases bullets.
A very tiny percent of charge pressure that is way less than pull force.
I was surprised when I read Tonys book on testing new barrels. I have found shooting primarily 2 cartridges for close 25 yrs my loads from barrel to barrel seldom vary much. I think a very important component is using the same reamer for every barrel. With the 6 BRX I feel confident I have a load that only requires minor tweeking in seating depth 99% of the time in either a Bartline or Krieger barrel. I had 2 exception out of 20 some barrels, one Douglass and one Shillen. They both wanted about a grain less powder.
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