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Bullet Runout

 
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  #1  
Old 12-30-2006, 06:33 PM
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Join Date: Dec 2004
Posts: 139
Bullet Runout

Hi Guys,

I have intently read the last post on bullet runout. Since I have been off work over Christmas vacation, I have had some time to play in the garage a little bit.

First thing I did was to build my own Runout Guage. Built from odds & ends ranging from my fathers dial indicator from the 60's to my son's errector set that I just bought him for Christmas.
Here are Pics of my Runout Guage:
Ok, Don't Laugh, I'm sure there must be a clause against it somewhere on this site!

I started with my older sons old skate board wheel bearings, 5 of them. I happened to have a rod that fit the center of the bearing perfectly. I spaced the 4 bearings with nuts, that also fit the rod just right. This allows the case body to rotate or spin, without moving (better than a v-block in my opinion). The 5th bearing is used as a hard stop for the back of the case.
I then drilled a hole for the Dial Indicator Post (smaller than post dia). Post is press fit into 2 3/4" thick wooden block (left over from front door project)(all rods are press fit into wood). Now I had my guage ready to work. You could spin it by hand but had to be careful to apply steady even pressure on back of case as you rotated it. I improved this by stealing a few components from my youngest sons's errector set. This became the spring loaded pressure arm which presses the case into the roller bearings and angled to apply pressure against the 5th hard stop brg. I can now easily turn the pink wheel to make the bullet rotate in the guage with constant spring pressure.

It works really well, I put the indicator on the bearings to make sure they ran true, and they do!

RESULTS OF CHECKING LOADED CARTRIDGES: "TIR = total indicator reading"

I checked my .270Wby cartridges that I load for my Kirby chambered .270Wby Mag. I found that my bullets were out of round from .0005 (almost perfect) to .006 (worst case).

Some intersting results from testing:
I checked the Neck runout on brand new .270Wby weatherby brass. Most of of the cases were almost perfect with the worst being .0005 TIR. I then put the near perfect cases thru my Forester full length die with expander button removed. What I found surprised me. After coming out of the die, the necks could be misaligned and gave a .001 TIR. But not every time, only some of the time. I tried the 1/4 turn method as you go thru the neck, but still could deform the neck by .001.

I then sorted out the cases that had necks that were no more that .0005 out of round with the case body. I loaded bullets (140 gr. Accubonds) into these cases using a Forester Ultra Micrometer bullet seating die and took measurements. Again I was very surprised. Some of the bullets seated perfectly with no more than .0005 TIR, but others showed as much as .006 TIR.
I contemplated and looked inside the die. Insid the die the it looks like the chamber is designed to fit the case and guide it perfectly. But their is nothing that fits around the bullet to align it to the neck. In other words what ever the wall thickness of your neck (in my case .014 x 2 = .028). So the bullet can flop around .028 within the bullet seater die. Add to it the clearance necessary to allow the spring loaded sleeve to slide and that number increases. Now you may say, doesn't the seater cone center the bullet. Well yes but only to a small degree. The seater cone is designed to be universal to a bunch of different bullet styles and there fore cannot match every bullet perfectly. And even if it did, it is not set in a precision aligned bore. More likely it's designed to float so it can conform to the hole in the neck.
So where do we go from here? [img]/ubbthreads/images/graemlins/crazy.gif[/img]
I tried to seat some bullets with an old RCBS bullet seater and got slightly better concentricity then the Ultra Micrometer Seater Die. Reason = Removal of extra clearance that allows the spring loaded sliding chamber to move.

FROM HERE WE GO TO SEPARATING OUT THE PERFECTLY CONCENTRIC LOADED CARTRIDGES FROM THE OUT OF ROUND CARTRIGES. TAKE THEM TO THE RANGE, TEST FIRE AND RECORD RESULTS:


Rifle's used: .270Wby deep fluted Heavy barrel, by Rock Creek "5R" Smithed by Kirby, in a Bell & Carlson Stock.

Second rifle, .257Wby Action with my old .270Wby 24" stock barrel slapped on in Laser Mark Stock.

Pics of target with orange bulls were shot with Heavy barreled rifle.


1. (no fouling shot) Upper Left, .63" group, TIR=.0005 Load=7828-69.5, 140Accubond

2. Upper Right, .9" group, TIR=.0005
Load=identical to above

3. Lower Left, .56" group, TIR=.004-.005
Load=H1000-72.5, 140 ballistic tip

4. Lower Right, .375" group, TIR=.001
Load=IMR7828-70.2, 135 SMK

CONCLUSION: Meichele is correct, No other sport is frustrating enough!!

It did not seem to make a big difference to accuracy in my case, at least not at 100 yard range.

Now we need to ask why?

Well, what happens when a bullet hits the barrel when it is not perfectly aligned with the bore. Now this is just my theory! The bullet gets shaved or deformed on one side, by the amount that it is out of alignment.

What does this do?: Nothing intitially. The bullet gets squeezed/swaged into the bore (gasses should be sealed behind bullet). Once the bullet leaves the bore, it may now be lighter on one side by the amount shaved off. As the bullet spins it stabilizes as it flies. If however, it is lighter on one side than the other (out of ballance) it may begin to gyrate and it may depart from its original trajectory. This may not be evident at 100 yards, but it may be much more prominent at say 600 yards. Again I am speculating.

Now here is the target from my other .270Wby with 24" barrel:

Here you see that the barrel likes 2 loads a lot better than the other 2 shown.

1. Upper Left, 2.63 group, shot-1=.0005 TIR, shot-2=.002 TIR, shot-3=.006 TIR.
Load=7828-68.5, 150 SST

2. Upper Right, .81 group, shot-1=.002 TIR, shot-2=.002 TIR, shot-3=.005 TIR
Load=7828-68.5, 150 Speer boat tail

3. Lower Left, 1.06 4 shot group, shot-1=.002 TIR, shot-2=.003 TIR, shot-3=.005 TIR, shot-4=.007 TIR
Load=7828-73.5, 140 TSX

4. Lower Right, 2.56 group. This bullets were the exact same bullets with .001 TIR that shot excellent in the other rifle.
Load=7828-70.2gr., 135SMK

Conclusion: Barrel harmonics/powder charge, bullet type & weight may have more to do with accuracey than bullet concentricity. And I'm tired of typing [img]/ubbthreads/images/graemlins/tongue.gif[/img]

Good day,
Vic
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  #2  
Old 12-30-2006, 08:37 PM
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Join Date: Sep 2001
Location: medford wi usa
Posts: 273
Re: Bullet Runout

People are going to chime in and say you haven't done enough shooting to prove it statistically. What you found is what I have been saying a long time. When a gun likes a powder charge and bullet it will shoot it JUST GREAT whether there is zero runnout or not. Has anyone ever proved or photographed a bullet entering rifling at "ignition time". I haven't heard of it. Who knows how much (or little) deformation happens as the bullet enters. Also.....isn't that why we buy good barrels.....doesn't the trip down that high quality match grade barrel count for anything.
Benchrest might be another matter where 10th's of an inch win a match. But you average shooter with even a great hunting rifle is probably better off experimenting and finding the magic load.
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  #3  
Old 12-30-2006, 08:38 PM
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Join Date: Sep 2001
Location: medford wi usa
Posts: 273
Re: Bullet Runout

BTW----love that runnout gauge!!!!!!!!!
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  #4  
Old 01-02-2007, 10:00 PM
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Join Date: Dec 2004
Posts: 139
Re: Bullet Runout

Ok, I did some more discovery,

I measured my 270Wby Cases after firing in rifle:
Neck Dia = .303
Body Dia (where radius meets straight portion)= .495

Dimensions after sizing in Forester die (no button):
Neck Dia = .2965
Body dia = .492

Dimensions after sizing in RCBS die (with button):
Neck Dia = .299
Body Dia = .4925

RCBS Die leaves the brass slightly larger than the Forester Die. This would indicate a tighter fit/better alignment in chamber.

I also did a concentricity measurment on the cases after firing. The necks seemed to be in perfect alingnment with the body according to the concetricity gauge.

I then did a full length re-sizing in both dies and measured for concetricity. Both dies produced brass with the necks anywhere from perfect to .005 TIR.

I recall reading a previous post where somebody said to rotate the case in the die as you incrementally press the brass up into the die. This did improve concentricity on the neck readings. Average TIR with the Rotation method produced necks that were within .002 TIR and many better than that.

Note: I found that once the brass was fully formed in the RCBS die and it was .005 off center, you could not put it back in the same die and perform the rotation operation and improve the runout.
However, since the Forester die is a bit tighter (.0025), If the case is out of round after sizing in the RCBS die, I can size it again in the Forester die, utilizing the rotation operation as I press it in, and I can correct the runout substantially.

Conclusion: Rotating the brass as you incrementally press it up into the die will produce better aligned necks on your brass.

Next step was to try the rotation operation while incrementally seating the bullet.
This did not produce any benefits for me. It seemed that if a bullet started at an angle, It continued that way no matter how carefully you rotated it as you fed it upward. [img]/ubbthreads/images/graemlins/frown.gif[/img]

Getting the bullet to start straight seems to be relegated to blind doo daa luck. [img]/ubbthreads/images/graemlins/tongue.gif[/img]

I read XPHUNTER's thread about the Bersin tool and decided to make a similar tool to see if it really could have an effect. Here is a pic of my version of the tool.




Here I took a body die, drilled a hole in the side to fit a BB (from son's BB . The full clearance hole for the BB does not go all the way thru. It allows the BB to protrude, but not fall out. Then I drilled another hole behind it and tapped it for a bolt.
The bolt is screwed in and it pushes the BB against the bullet, similar to the operation of the Bersin tool http://www.kinneman.com/index.asp?Pa...stom&ID=1.

I am sad to report that my tool was a total flop [img]/ubbthreads/images/graemlins/confused.gif[/img]

It seems that it takes too much force to bring the bullet back into perfect alignment, and how do you know how far to go? You have to go past the point of elasticity to get the brass neck to hold it's shape and not spring back. How far is that, how do you guage it accuratley every time. I don't know. Even with a guage on the unit, I'm not sure that you can bring an out of round bullet back into alingment in a practical sense.
My tool only put a dimple in the brass if I tightened the bolt to push it over. If I rotated the bullet, it left a groove on the high side. When measured on the concentricity gauge, there was no improvement. [img]/ubbthreads/images/graemlins/tongue.gif[/img]

Seems like the only way to get a bullet seated concentricaly is to seat it straight from the get go.

Oh, one thing I did discover is that the long chamfered boat tail bullets like the SMK, ended up with much better alignment then the Nosler Accubond boat tails with the real small chamfer. This seems obvious by simple observation, but I had to prove it out just to be sure.

As Kraky mentioned this imperical data that I have collected is based on a very small sampling of bullets, so it does not carry a lot of weight. But it at least gives me an idea of what works and what does not work and tells me where I need improvement in my reloading methods.

The next step will be to turn the necks and see how much that helps. If the outside diameter of the neck is perfect and the bullet is .005 off, than it is either the bullet is canted inside the neck or the wall thickness is off and that is throwing it out of alignment (this seems to never end, doesn't it).

That being said, does anybody out there have any secret bullet seating dies that produce loaded bullets with superior alignment characteristics?

Best Regards,
Vic
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  #5  
Old 01-02-2007, 11:14 PM
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Join Date: Sep 2001
Location: medford wi usa
Posts: 273
Re: Bullet Runout

Here' what I post regarding getting normal dies to make the very best runnout. I have several sets of hornday and forester dies that routinely make loaded ammo at .002 and under and often .001. I do try to make straight ammo but firmly believe after doing some testing on my own......THAT NONE OF MY FACTORY RIFLES KNOW THE DIFFERENCE BETWEEN .001 RUNNOUT AND .005 RUNNOUT. I have a friend that I load for that does some long range "predator" culling around his fish ponds and he says the same thing. (I used to sort his ammo based on runnout).
Anyhow below is what I always paste about setting the sizing ball/spindle.....

---ALL dies with expander balls need tuning. Think about it...a piece of typing paper is .003" thick--what are the odds that the expander is not PERFECTLY centered in a die and could pull a case slightly off center??? Pretty good I'd say. Pull the expander stem out of the die (and now is a good time to clean the inside of the die). Run about 5 brass into the die and see if they come out concentric. If they do (and usually they will) you now have to try and get that stem centered on re-assembly. A great way that helps is to put a piece of very concentric brass up into the die to hold the stem in place as you tighten it down. Sometimes this takes 2 people unless you have 3 or 4 hands. AFter reassembly try sizing some brass and check runnout. If not good then do very small turns of the expander stem--probably 1/32 of a turn at a time. Resize some brass and repeat the small turns. At some point I can almost guarantee that you will get GREAT RUNNOUT CONSISTANTLY. (Somehow, someway the expander spindle will hit almost perfect centering in the die body) I have many dies that consistantly make less than .002" runnout after sizing with most of the brass at .001" and less. I own, hornady, redding, forester, rcbs, and lee dies. ALL OF THEM HAVE BEEN TUNED and most make fantastic ammo and all make good ammo!! I have never ever got a set of dies from any factory that made as good of ammo as those that I have done this simple work with.
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  #6  
Old 01-03-2007, 03:20 PM
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Join Date: Dec 2004
Posts: 139
Re: Bullet Runout

Kraky,

I hear you on the Brass resizing issue. Altough I did find that even without the sizing button in the die, If I pressed the brass up with one single stroke and pulled it out, the runout was hit and miss (between .000 - .005 TIR). However if I rotated the brass incrementally as I pressed the brass up into the die, I got much better neck concentricity.

Also, I agree with tuning of the expander button if it is close up near the neck. Some dies have the button way at the bottom of the die, so its concentricity within the die does not matter nearly as much since the neck is not in the neck constricting portion of the die. At the bottom there is nothing but air around the neck and the post button stem will flex or the case will cant a small amount to clear the eccentric position of the button. In other words I don't think the long stemmed button has enough ridity to bent the neck.

Anyhow, Have you found a die or tuning method for Bullet Seating?

That's where I have my biggest problems.

Nice talking with you Kraky,
Take care,
Vic
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  #7  
Old 01-03-2007, 04:13 PM
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Join Date: Sep 2001
Location: medford wi usa
Posts: 273
Re: Bullet Runout

All I can say re seating is just get it started...give a turn....seat aways....turn....etc etc. Also be sure to chamfer "straight" to the case mouth. And....I also use a vld chamferer as I found the normal rcbs leaves a tiny ridge that the bullet sort of "pops" over when seating. You can't get 'em all perfect but if you get about 85% that's great. Like I said...in my guns for max 400 yds shooting runnout isn't going to make as big a difference as how the gun likes the loads. ON THE OTHER hand I realize some guys here hunt at 1000+ yds.

I'd like to hear from them what they think about the runnout issue in their custom LR rifles.
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