Neck Tension on Accuracy

[archmaker]

I just bought me a copy of Shooting Steel (loaned my copy to friend a decade+ ago, and never got it back) and there was an interesting article that explained what I believed.

He was talking about weighing the force required to seat bullets when seating them in his 44mag cases.

He found that those that took minimal effort shot to a different POI versus those that took substantial force.

Also he found this was more apparent with lighter bullets vs heavier bullets.

Now I know that my heavier bullets produced on the average smaller groups easier (less load development) then the lighter bullets. His reasoning was that those with less neck tension were having their bullet go further down the barrel/chamber before it all burned vs those with more tension where more of the powder was burning in case.

Just thought I would share. :)

[44man]

I just bought me a copy of Shooting Steel (loaned my copy to friend a decade+ ago, and never got it back) and there was an interesting article that explained what I believed.

He was talking about weighing the force required to seat bullets when seating them in his 44mag cases.

He found that those that took minimal effort shot to a different POI versus those that took substantial force.

Also he found this was more apparent with lighter bullets vs heavier bullets.

Now I know that my heavier bullets produced on the average smaller groups easier (less load development) then the lighter bullets. His reasoning was that those with less neck tension were having their bullet go further down the barrel/chamber before it all burned vs those with more tension where more of the powder was burning in case.

Just thought I would share. :)
I find it funny you found that! It is MY article (Jim Miner).
I wrote that before I had BR dies made that were a pain to use and then found Hornady dies saved me work.
I made a measuring device to seat bullets that allowed me to shoot 79 out of 80 at Ohio state with my SBH. Unheard of from a Ruger back then. I was rattled and missed the last ram. After cleaning 20 turkeys and 19 rams I was shaking too much and tired.
I was using the Hornady silhouette bullet, 23 gr of 296 and the Fed 150 primer.
I shot many 40's after that with cast because it works better for cast then it does with jacketed due to the boolit lube changing friction in the brass. This requires more even tension and you need to have the right hardness to resist sizing the boolit when seating.
It is not that they need to be real tight, just very even from case to case. Can't have a few loose and a few tight.
New, unfired brass is very bad so shoot the brass a bunch before looking for groups and sort out brass that causes fliers.
As I have said 1000 times---THINK BRASS for accuracy.
Ever notice that BR shooters use the same brass for record, loading them over and over at the bench?
Small world that my work shows up here after all these years! :lovebooli

[randyrat]

Bingo, another piece of the puzzle when your working for accuracy. It's one big variable that i can't always control due to the many different makes of brass i have. It seems they all different wall thicknesses.
I find it in all calibers that i shoot also.

Wall thickness will defentently throw your consistancy off, simply put, due to different grip on the bullet.

[felix]

In general, using a notch or two faster powder (for the same "load") tends to overcome the variance in static inertia that is limited to boolit tension and crimp together. ... felix

[excavman]

We're always looking for ways to improve loading technique. I wonder if weighing brass of the same lot for consistency would help in the neck tension area as well as case volume. There is also the never ending crimp/no crimp debate, does anyone have info on that one? I am always willing to learn.

Larry

[44man]

In general, using a notch or two faster powder (for the same "load") tends to overcome the variance in static inertia that is limited to boolit tension and crimp together. ... felix
This is true but hard to do in the .44 and maintain long range accuracy.
It is a strange puppy and some powders just don't work. Then the boolit needs to be harder as powder speed goes up. Anything you do brings in more problems to solve.
Even changing the primer will blow accuracy out the window and a mag primer defeats case tension in this case that is just a little too small for the pressure of the primer alone.
The closest you can get is 2400 with a standard primer but I never got the extreme accuracy from it.
The easiest way is too use good brass like Starline and dies that do the job. That cuts down the work.
Federal brass used to be good. I use Remington now and it needs shot for a while to even out. Midway brass used to be pretty good.
WW does not do it for me. Hornady is pretty soft but is fairly even and gets better as shot.
Funny that I shot the smallest groups at 200 meters with the 4227's in load work, yet had the worst ever problems with it on the range. It will never go in the .44 again.

[felix]

All too true, Jim. You can safely say fast powders do not work for heavy-duty loads. ... felix

[Larry Gibson]

archmaker

"He found that those that took minimal effort shot to a different POI versus those that took substantial force.

Also he found this was more apparent with lighter bullets vs heavier bullets.

Now I know that my heavier bullets produced on the average smaller groups easier (less load development) then the lighter bullets. His reasoning was that those with less neck tension were having their bullet go further down the barrel/chamber before it all burned vs those with more tension where more of the powder was burning in case."

FYI

The proper use of a chronograph during load development would have pointed out this problem very quickly. Knowing how a high ES and an SD with an improper relationship to the ES shows inconsistent ignition. This is the actual problem with such loads. The author, 44man, came to the basic conclusion via different analysis but using a chronograph would have gotten him there quicker. I began using a chronograph (Oehler M10) in the mid '70s and it's use very quickly pointed out such revolver loads in my .44 and other revolver cartridges.

However, a carefull balance of neck tension must be maintained when using soft cast PB'd bullets. The neck tension, if too much, can easily swage down the seated portion of the bullet and cause other accuracy problems. Simply means that there are rules to this game but in most cases there are always caveats to them.

Proper neck tention is indeed an imprtant consideration in load development not only with cast bullets but also with jacketed bullets. It is apparent more so in revolvers with magnum cartrdge loads than with closed breach firearms or some cartrodges.

Larry Gibson

[44man]

We're always looking for ways to improve loading technique. I wonder if weighing brass of the same lot for consistency would help in the neck tension area as well as case volume. There is also the never ending crimp/no crimp debate, does anyone have info on that one? I am always willing to learn.

Larry
No, weighing does nothing for the revolver.
Case tension that is even is best and just enough crimp to hold boolits under recoil. Too much crimp can ruin a boolit, either when crimped or when the boolit has to force it open.
I worked a long time with crimp from a full profile to none at all in revolvers. With the right alloy there is no difference in accuracy but you must shoot non crimped boolits single shot. There is little change in POI by changing crimps.
Chrono results with crimps show little variation and it can bounce back and forth so if you ask me if a tight crimp aids burn rate I can't say for sure. Never proved it.
As I get to heavier boolits I use harder boolits and tighter tension but do not increase crimp.
In rifles I always found accuracy and never crimped except for lever guns. Case tension is not as important but does help and is still the best way to go. Case volume is more important then in a revolver. You can anneal rifle brass to even it out.
The revolver is the hardest to work out. But the darn thing will shoot.
My love affair with the revolver will never end! :bigsmyl2:

[44man]

archmaker

"He found that those that took minimal effort shot to a different POI versus those that took substantial force.

Also he found this was more apparent with lighter bullets vs heavier bullets.

Now I know that my heavier bullets produced on the average smaller groups easier (less load development) then the lighter bullets. His reasoning was that those with less neck tension were having their bullet go further down the barrel/chamber before it all burned vs those with more tension where more of the powder was burning in case."

FYI

The proper use of a chronograph during load development would have pointed out this problem very quickly. Knowing how a high ES and an SD with an improper relationship to the ES shows inconsistent ignition. This is the actual problem with such loads. The author, 44man, came to the basic conclusion via different analysis but using a chronograph would have gotten him there quicker. I began using a chronograph (Oehler M10) in the mid '70s and it's use very quickly pointed out such revolver loads in my .44 and other revolver cartridges.

However, a carefull balance of neck tension must be maintained when using soft cast PB'd bullets. The neck tension, if too much, can easily swage down the seated portion of the bullet and cause other accuracy problems. Simply means that there are rules to this game but in most cases there are always caveats to them.

Proper neck tention is indeed an imprtant consideration in load development not only with cast bullets but also with jacketed bullets. It is apparent more so in revolvers with magnum cartrdge loads than with closed breach firearms or some cartrodges.

Larry Gibson
Well said Larry but the chrono never was an aid and drove me nuts.
My best loads never showed small ES or SD. Trying to make these figures smaller always made worse groups. I learned to leave the thing in the house.
You would not believe how bad some of the shots read that print into an inch at 100 yards is.
I once worked to the smallest ES ever with a gun and got the largest groups I ever shot. I think I was at 3 fps difference. My best load in the .44 has an ES of 29 fps but increasing the charge takes it to 26 fps and widens groups.
I will not depend on that machine.

[excavman]

I was doing some load developement last weekend and using my chrono extensively. I found out real quick that there was no relationship between group size and velocity variations when shooting a 125 gr cast gc boolit in a 270 win. The type of powder was the thing that made the most difference, 2400 grouping the best of all.

Larry

[HeavyMetal]

I'll agree that ES and SD are often "touted" as the tools for working up a load by some of the gun mag writers, although I have not seen it pushed recently, but in the real world ES and SD are numbers for "Show and Tell" and nothing more!

My use of a chorny is to determine velocity, versus case expansion, and average velocity so I can quote an average, repeatable, velocity for a specific load.

Back in the day IPSC had a Major / Minor power factor level, and still do, and being able to look the RO in the eye when he questioned my power level was worth the effort.

Group size is everything, ES and SD mean nothing if the load won't shoot!

[HeavyMetal]

I also read 44man's article many years ago and it has been the driving force in much of my load devlopment in my 44 model 29 well as other pistol and rifle rounds.

Never shot a Metalic Sillywet match, I will someday, but I can scare the snot out of a milk jug full of water at 200 yards on a good day.

44man's info is good solid stuff for wheel gunners!

[Larry Gibson]

Not wanting to start any argument here or any controversy. I merely am pointing out that the use of a chronograph and its data can be very helpful.

Not understanding the data or what it is telling you can cause confusion and frustration. That is easily seen with the comparison of accuracy to velocity variations mentioned. The data from the chronograph relates directly to internal ballistics (uniformity of the load). The "accuracy" or shot holes (groups) in the target relates directly to external ballistics. Internal and external ballistics are two different animals. In comparing the two we should only consider that at a minimal test distance of 25, 50 or even 100 yards given equal acuracy on target, the load with the more uniform internal ballistics will be the better load. Accuracy between the muzzle and the target is affected by numerous things; correct bullet, sufficient stabilization, correct "launch" (geez, I really hate using tht term!), RPM, imbalances in the bullet, weather conditions, shooter's ability to shoot, etc., ad nauseum. Internal ballistics is not affected by any of those. Internal ballistics will demonstrate only how well the round has bee loaded and how consistently the components interact during ignition, combustion and acceleration.

I also am a strong proponent of not chasing the ES/SD god. Understand that several 10 shot strings of a given load will invariably give different ES, SD and average velocities. That is known and given but the variances must be within acceptable variation. A continual search for the lowest ES or SD or a combination thereof is frustrating and pointless as 44man points out. I will say it again; what you should look for is an acceptable ES given the cartridge, components and firearm and an SD that is within 20 -45% of the ES. Again, a sufficient sample must be shot to determine this. A five shot test string will only give an idea, a 10+ shot test string is minimally acceptable giving about a 90% probability that the rest of the ammo of that load will fall within the measured results.

A one time 5 shot test load that gives a 1 moa group at 100 yards (using the .270 for example) and has an ES of 150+ fps is not going to be an accurate load. The next testing of that load or shooting at longer distances may very well be 3 moa. That load would not be worth pursuing without some serious change to components or loading method (using a filler for example). Conversely, a load that gives an ES of 50 fps or less and shoots 5 shots into 3 moa is also not worth pursuing unless a serious change is made that brings the target results in line with the chronograph data. What we want is a load that gives both and acceptable ES/SD and good on target accuracy. Using a chronograph's data and the target data (group size and dispersion) will get us accurate loads a lot quicker than just using one or the other.

Back before I got my 1st chronograph I worked up loads like every on else; I shot handgun groups at 25 yards and rifle groups at 100 yards. The 5 shot load that gave the best group was "the load". However, many times it just did not work out that way. I shot a lot of long range target matches and also a lot of long range rock chucks. Many times “the load” gave poor accuracy beyond 100 yards and in particular 300+ yards. I was also doing some longer range shooting with my 357 and 44s and found the same thing. I went back to the loading bench/range and developed other loads that were accurate at a100 yards for the handguns and 300 yards for the rifle. That took a lot of time and component expenditure. Then I got an Oehler M10 in the mid ‘70s and quickly discovered that the good long range loads had much smaller ESs than the previously thought good loads developed at 25 and 100 yards. Subsequently, I have found that any load that gives an acceptably low ES and also gives good accuracy at 25 and 100 yards will also shoot very well at longer range. If one does not coincide with the other then accuracy over any practical range will suffer.

This is not to say we can not work up accurate loads without the use of a chronograph. You can still certainly do that. However, it is much easier if both chronograph data and target data are used. That’s all I’m saying.

Larry Gibson