changes to point of impact with neck tension

[Mulligan]

This round-robin neck tension test was shot yesterday afternoon at 600 yards in Western Colorado, mid 30’s, cloudy, for us- light winds.

I plan to go out and retest to verify
But thought I would share this one because you can clearly see how the point of impact changed with small changes in neck tension.

This was shot round-robin……… a 12 shot string.
Each bullet hole has the shot number written beside it.

For example the the yellow group is the three shots where I used a forester die with a 260 honed neck and inserted a .238” mandrel into the case neck, the shots were the 2nd, 6th, and 10th shots in the series of 12 shot fairly fast.

CW

 

[JFrank]

If it ain’t snowing and 10* this shit don’t count. Lol

Nicely done Clay.. green always shoots best..

 

[Mulligan]

If it ain’t snowing and 10* this shit don’t count. Lol

Nicely done Clay.. green always shoots best..

I will go out and shoot green and red again…..and both sides of red.

It really is amazing how small changes show up.
CW

 

[choprzrul]

Were there velocity differences for the groups?

 

[Mulligan]

Were there velocity differences for the groups?

I suspect it’s “harmonics”

Same bullets, powder, primer….weighted & sorted until the cows come home.
CW

 

[Mulligan]

Maybe I should have titled the thread
“Tony Boyer was right again”

In his book he writes that if you run the case up into the die a second time, remove the button, otherwise, it won’t go with the group.

CW

 

[6.5 forever]

A few weeks ago I lengthend seating by 8 thousand and cut by group sizes by half at 550 yards. The group also moved two inches right. Definitely a learning experience

 

[BoydAllen]

Years ago I did a less rigorous test using 133 and my 6PPC. Having been advised that .003 neck tension would give better results than .002, I had worked up what seemed to be a good load, and since I had the bushings, I decided to shoot the same load with .001 and .002 for comparison. The conditions were near perfect, I had flags out, the distance was 100 yards. Starting with .001 the group looked bad, .002 was better, and .003 put me right back where I started. At the time I did not have the bushing to try .004. This was probably over 25 years ago. Later on, when it came out, I tested LT32 to see what tension it "preferred" and it seemed to like less tension, .002 or a little less. Later I asked Lou Murdica (father of the LTs) how he shot the powder and he told me that he used light tension and soft seated (loaded longer than jam, so that the bullet would be pushed back as the round was seated) and that for 133 he shot more tension and seated into the lands but short of jam. When testing a new powder I typically start my powder charge test with .002 tension, and very light marks on the bullet. After I find a charge weight I like, I play with seating depth, and then neck tension, unless I am shooting a dot, typically not quite the case.

 

[ShtrRdy]

What if you looked at the red, green, and blue essencially being in the same general location, with a shot spit out from red and blue?

 

[jds holler]

Heck, me and any one of my rifles could shoot 12 shots into a group that small at 600 yds, you couldn't knock the smile off my face.jd

 

[Ccrider]

Maybe I should have titled the thread
“Tony Boyer was right again”

In his book he writes that if you run the case up into the die a second time, remove the button, otherwise, it won’t go with the group.

CW

What button?

 

[Mulligan]

Heck, me and any one of my rifles could shoot 12 shots into a group that small at 600 yds, you couldn't knock the smile off my face.jd

I hear you!

This rifle wants to shoot small, and it is fun to sort through all the "stuff" to get it there.

CW

 

[Mulligan]

What button?

Bushing,


Page 124



CW

 

[Tesoro]

Why dont you load up one batch at jam+ with NT on the tight side. Be interesting to see.
I guess this is why tuners are becoming more popular.

 

[quest450]

YES! definitely tuners.....and don't forget wind flags

 

[Dave M.]

This round-robin neck tension test was shot yesterday afternoon at 600 yards in Western Colorado, mid 30’s, cloudy, for us- light winds.
View attachment 1511329
I plan to go out and retest to verify
But thought I would share this one because you can clearly see how the point of impact changed with small changes in neck tension.

This was shot round-robin……… a 12 shot string.
Each bullet hole has the shot number written beside it.

For example the the yellow group is the three shots where I used a forester die with a 260 honed neck and inserted a .238” mandrel into the case neck, the shots were the 2nd, 6th, and 10th shots in the series of 12 shot fairly fast.

CW

Interestingly, the tightest group appears to be the most neck tension without any mandrel work.

 

[Ned Ludd]

What button?

I think he means to remove the expander ball (i.e. "button").

 

[jds holler]

I can be a sick bastard, but think of this. What if neck tension had nothing to do with your results, and shot #s 3,12,10,and 6 just happened to be outliers for some other devilish reason.

 

[Mulligan]

I can be a sick bastard, but think of this. What if neck tension had nothing to do with your results, and shot #s 3,12,10,and 6 just happened to be outliers for some other devilish reason.
View attachment 1511421

It is plausible,
However, for all three of the yellow shots to be independent and all three blue shots to be independent......... would be highly unlikely...........
Considering the only ink to "overlap" was for one shot and they were shot in a sequence of
1 Green
2 Yellow
3 Red
4 Blue
5 Green
6 Yellow
7 Red
8 Blue
9 Green
10 Yellow
11 Red
12 Blue

I think it is normal exit timing differences.
CW

 

[JFrank]

@Mulligan
Clay, when you shot this series were you trying to compensate for wind direction?
What was your original point of aim ?