Case Runout

[Brent]

I got my Redding S sizer die for the 300 Ultra and was doing a little checking of cases on the runout guage with various cases in different states.

I was concerned with starting with zero runout of the cases before loading so I checked the cases that were just fireformed first. I found runout of between .002" and .005" on all ten cases I checked, hmmm...

Now I wanted to know if my chambers neck area was off center. I went back and used a magic marker and placed a line on the shoulder when the dial indicator was showing the extreme point of displacement of the neck. I then stood all cses up in a row with all the lines facing me. I looked at the cases carefully to see for evidence that the case necks were offset to the same side in relation to where they had beeen in the chamber. What I found was an angled scratch just below the shoulder that was on all cases in the same exact place in relation to the marks I put on all the cases. My chamber was indeed without a doubt off center.

Now that I know this is a fact, I tried to correct the runout with the bushing die. The runout remained in the same spot and by the same amount.

Now I checked the cases I had fired but then full length sized with my other die. All had less than .002" runout with most less than .001" and some zero.

The FL die was obviously straightening these cases out and the Bushing neck die was not. By this time I'm very disapointed but not really surprised by the different sizers affects on the already less than perfect cases, it made sense that the neck die would have less of a straightening effect in other words.

I do not want to FL size cases period, it is so much faster not to lube then neck size it isn't even funny. I did fifty cases in about 3 minutes on my Dillon so...

FL sizing will produce more concentric cartridges than the neck die will with fired cases out of this chamber but I'll find out how much difference on paper it makes shortly, IF I can EVER get to the range.

[ 12-15-2002: Message edited by: Brent ]

 

[AJ300MAG]

Brent, I had a problem with both my .300 & .338 Ultra's and the Rem brass. I was getting 8 out of 20 rounds with bullet runout over .005". When I checked the necks after firing, the neck runout was zero for the .338, and .0015" for the .300, which told me that my chambers were concentric to the bore. When I checked the inside of the neck, I was getting .0025" or more runout. To make the O.D & I.D. of the necks concentric I neck turned the brass only enough to get 85% clean up, took less that .001" a side off to true them up. Most pieces had 100% clean up. I set up my full length sizing die to just bump the shoulder back .001" so the bolt will close without any resistance. Another thing I did find was that the expander ball was inducing some runout in the neck also, even though the die was perfect. I tried all the usual remedies to fix but didn't find a cure. I made up a seperate expander mandrel like the one Sinclair has to expand the necks for neck turning. I set it to give me .002" neck tension. Using this method I'm getting 2-3 "rejects" per 20 rounds now. I realize you don't want to use this process when mass producing ammo on a Dillon, but its helped my load accuracy for hunting ammo.

 

[Brent]

Al,
I don't use the Dillon in the progressive sense that it is intended way anyway, I size all of them in the first position then do all my prep work and seat in the second station.

I have a carbide expander ball for the Redding dies and I use it to straighten out the screwed up necks on new brass and it works great, no lube needed and no necks to delube later. My 308 die doesn't leave too much tension without using the expander ball so it isn't used on it.

The check I did on the 300 Ultra FL sized brass used the expander ball because it squeezes the cases down too far unlike the 308win die I have. I haven't checked the Ultras runout without the expander used.

I was going to turn the necks, at least clean up 80% or better then I wouldn't need the expander anymore with the FL die, tension would then be about right with the thinner necks.

My pilot for the Forester turner is a tad too small and the case can literally be held up off the pilot and when the collet is tightened on the casehead and the case will stay off center of the pilot and cut the neck thinner on the side the neck it pushed tward when tightened, get the pilot too big and there a pain to work with too.

When I found the chambers neck to be off center I now wonder if the neck is centered with the bore or the case body is.

I had planned on leaving some of the neck unsized to help center the neck a little better with the loose factory specs and all, but now I wonder if I'm better off seating the bullets hard into the lands to center things up and leaving the necks sized all the way and loose to let the bullet center up, hell I don't know. I thought I might index the cases to the same position they were fireformed at and see how this worked too. I see a few tests down the road. Interesting little details can consume lots of time at the bench. I hope they shoot well with the neck sized cases reguardless of the runout, am I asking too much?

 

[Guest]

[ 07-12-2003: Message edited by: S1 ]

 

[AJ300MAG]

Brent, when I turn my necks I use the Sinclair tool . You have to use a special arbor to open up the necks so they are a tight slip fit on the turning arbor. Yea, it's a lot of work but you only have to do it once. I also tried to turn the necks to the point that when you ran them thru the sizing die, the die would compress them down to where the expander ball wouldn't open them back up. I didn't see any difference in accuracy between the two methods I tried. The only thing that bugged me was that gas was getting around the neck, the shoulder still sealed the chamber. Everything I've read seems to be that you want less than .002" total bullet runout for best accuracy out past 200 yards. I'm kinda picky with my loads. I can't blame the rifle when I miss, It's usualy the jerk behind the trigger. I guess it what your expectations for accuracy are to how much work you put into your loads. Mabey you could find a machinist who could make you a pilot for your trimmer. I haven't see a Foster, I make my own for my RCBS case trimmer.

 

[Brent]

Forrester will make them whatever dia you need them but I just haven't got the one I need yet. I pollished the one I have down too much, so it's my fault it doesn't fit a tight now. I hadn't realized the collet would torque the case as much as it does. I could just pollish down an expander ball some to acomplish the same objective too.

I have my eye on a K&M turner for the future, I've heard nothing but the best about them so far.

I could have the chamber recut on the gun but it isn't worth the cash with the factory barrel in my opinion.

 

[kidcoltoutlaw]

i ran into a bullet runout faq the other day now i can't find it .anybody know where one is,thanks,keith

 

[MAX]

Brent, sorry to see you've gotten lost in the insanity of run out

. Keep pluggin' away... I do a lot of things these days with die set up that are different than before I purchased the Casemaster. One is that I generally have better success with loose than tight, letting dies find a natural center. If I use an expander ball at all it is on the down stroke, as a separate step. Another is I ditched a lot of RCBS dies, but not all. A cockeyed chamber is...there is no word for that, sorry.

Try this for giggles: Next time out take your indexed loads and fire three groups of 3-5 rounds, w/ the index mark at 9 o'clock, 12 o'clock, then 3 o'clock. If you see no difference I'd guess your chamber cut is having little influence. When I do this with R.O. above .003", I generally see 3 distinct groups on the paper, even at 100 yds. Luck to you.

 

[Vern Harrison]

Hi guys,

This involves a little work at first but great results in the end.

I have my 1000 yd LG match rifle chambered in 300 wm. My run out on the bullets were about .007/.010 way to much.

After weighing my cases, cleaning up primer pockets and flash holes. I F/L size in my RCBS die. Then with my Forester lathe I inside neck ream. Then run it through my K & M expander plug, then turn my necks to 12 1/2 thous. I then run the cases back through my Redding F/L bushing die with a 331 bushing.

Now my run out is less then .001. A lot of work but at 1000 yds, it all makes a difference. I know theirs guys out there that don't weigh cases or trim primer pocket, flash holes or turn necks. Then at the matches shoot single diget targets, but how much smaller would they be if they had removed all the variables from the cases.

One of the most important variables we have not been able to control, I feel is how tight we seat each bullet. I see now K & M has a new arbor press with a dial indicator on it to do just that! With the use of a Wilson straight line bullet seater we can now gauge how much tension it take to seat each and every round loaded.

I have been bitching about this last variable for ten years now, I guess it's time to shut up and same some money for this new tool!

Good luck, Vern

 

[Brent]

I've got my RO problems handled thus far, took some work but now I'm down to .000" - .002" at most on the Ultra. The nice chamber in the new 30-338 LI is staying under .001" no problem, but those are neck turned and reamed with the K&M and the inside cutter mandrel so I'd expect better numers anyway.

The Ultra's were neck turned on the Forrester and it just doesn't do as good of job as far as consistancy in thickness goes. I had to loosen the collet and let it float a bit to keep from torquing the neck on the mandrel to one side so I didn't end up with one side cut thinner than the rest. Seemed to work much better but I wanted to keep the variation less than .0005-.001" so I got the K&M. Now we're really talking consistancy... under .0002" no matter where you check it. It also cuts a LOT nicer too. Doughnut removed and neck turned all in one operation as well.

Max,

I'll have to try indexing RO at a few places and see if it steers the groups around.

Whistle pig,

I'll be testing a product in a few days for measuring seating force in PSI, it will be released not too long afterward, soon as they know it's working as expected. It has a digital readout and uses a sensor under the shellholder, can't say muck more than that yet, not sure they want the specifics out on it quite yet. Should be a great tool, I know I could use it about now! I will say that it won't wear out, reads more accurately and has higher resolution than the competetors does, but will cost a bit more... I think. I talked with Ken at K&M about an electronic pressure sensor type measurment system a couple months ago and he said the cost of making them would be steeper so he didn't want to go that route when he did his. Ken knows his electronics too.

The guys developing this and some other very awesome things are intent on leading the precision shooting and reloading crew to new levels, all at a price the average shooter can also afford, which is the criteria. Stay tuned...

A new style chronograph is in development as well, not relying on "light". Consistancy and accuracy with this design, as well as the price tag will get everyones attention. It might be a little while if it all works out as expected, but I think it's coming too.

 

[Vern Harrison]

Hi Brent,

That new tool sounds good. If you really think about it seating tension is the last variable we can't control. As far as reloading.

I was at Clay Spencers the other day and he has been working on an electronic gauge also but, he pointed out that both the electronic and the dial indicator type tools need some sort of mechanical stop.

I have been buying tools from Ken at K & M for many, many years, I think I have everyone of his except the new Force Measurement tool. Saving my pennies now

We always talk about "feel" in regards to reloading but as Ken points out, it's impossible get it through just feeling hand pressure. Primer seating is another case.

Keep us updated if you would on the new tool, Brent.

Good luck, Vern