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Case Cocentricity

 
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  #1  
Old 11-30-2008, 01:54 PM
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Case Cocentricity

Hi gang I am new to the forum and have some technical questions on Rifle brass cocentricity. I just purchased a new Savage 12BVSS in 22-250 and 200 new WW Brass cases. I also have a new Redding Competition Bushing type die set. (Neck die, Body die and Seating die) I did the following to the unfired brass, Pocket uniform, Pocket de-bur inside, chamfer necks inside and out and sorted by weight. I did not turn the necks and would prefer not to. I did run them through the Neck sizing die with the appropriate bushing (.249) Neck OD less .003 as recommended by Redding. This operation just barely affected the necks if at all. I have neck runout of +/- .002 to .005. Here is my question: How can I get the brass closer in cocentricity? I would like to have no more than +/1 .001 or less if possible. I loaded 20 rounds very carefully and the bullet runout is not acceptable. I have ordered a Redding Full length die, will that get the cases lined up better. If I fire the cases will they become more concentric? Any comments would be greatly appreciated!
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  #2  
Old 11-30-2008, 02:03 PM
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Re: Case Cocentricity

hey man, welcome!

I also have a 12 fvl 22-250 and encounterd similar problems with winchester brass haveing lots of runout (all had .002-.004 and some as high as .007). I messed around quite a bit with it and it seems that after being fired the first time runout decreased. I also opted to turn the necks and now I have vertually no runout. I don't use a bushing sizing die however so I have very low neck tension. I plan on continuing with my turning for the 250 but not in the wsm's I load for. After the initial firing and partial fl resizing I have runout of .002 or less on a few cases.

my personal theory is that the size of the shoulder compared to the size of the neck on the 22-250 makes it more suseptible to deformation due to the change in thickness of the neck on one side or another. Like I said, it's just my personal theory, doesn't mean it's true by any means lol!

good luck,
Mark.
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  #3  
Old 11-30-2008, 02:29 PM
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Re: Case Cocentricity

Hi Mark,
Thanks for your reply. I have been reloading for many years but recently decided to move up to the next level in reloading precision, man it's a whole new ball game. It is frustrating to buy such high-end dies etc. and know that I will not achieve the precision I wanted right off the bat. I believe that runout (Case and Bullet) is probably the biggest factor in poor groups. However I do think that these cases should improve with the first firing and then I should be able to produce some very precise cases and then hopefully very accurate rounds. I have had great luck in the past with standard dies in a number of calibers being able to achieve consistant minute of angle groups with hunting rifles so I hope to achieve some .5 or less groups with this Savage. I have a machinist back round and know that I should be able to achieve near perfect loads which should allow a good rifle to perform up to it's potential as long as I do my part. To me that is the challenge and joy in reloading!
Thanks for your input.

Nick
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  #4  
Old 11-30-2008, 02:42 PM
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Re: Case Cocentricity

I know what you mean about frustrating. When I first encountered my runout problems w/ the 250, I made a concentricity guage using an old dial calaper and some scrap wood and epoxy (pretty much jerry rigged but it works). Then I purchased a $99 redding comp seating die and was astonished to see runout yet. Then I turned necks and resized agian ---> still had runout! Next I fired the rounds and then resized them agian, No runout. So, I'm not certain if the turning really did it or if it was a combination of many factors.

I have been finding that with my rifles (all factory rem, Tikka, Savage, winchester) one of the biggest factors that helped me gain accuracy was creating a crush fit when chambering the rounds. I am not able to seat to the lands on any of my rifles so I have to rely on the case itself to perfectly center bullet to bore. I have started PFL resizing and have good results so far. For my WSM's I have comp shell holder set which is nice, but for my 250 I am simply backing the die off a little. I would like to simply neck size but I find that after a couple loads both my 22-250 and my 300 wsm get really sticky bolts and the groups go the heck at that point too. So, I have been simply PFL sizing all the time. Probably a little harder on the cases, but I want accuracy and reliability --kinda obsessed with it lol!
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  #5  
Old 11-30-2008, 03:41 PM
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Location: Mountians of SW NC, near Asheville
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Re: Case Cocentricity

Sadly, it seems from reading on the net, that problem is sorta common with those bushing dies.

I prefer the Lee Collet Neck sizers. They work necks the absolute minimum so case life is good. They need no lube, make straight necks and the neck ID is always right no matter the neck thickness. And no seater can make straight ammo if the necks are bent!

Understand that no sizer die can make non-concentric necks absolutely straight. Depending on your brass, you may need to lightly turn your necks, just a skim cut, to remove the worst of the high spots before you see much improvement.

And yes, shooting WILL make the necks pretty straight IF your chamber is straight. Thankfully, it seems most are but not always.

Try a light turning, Lee neck size, shoot and then Lee neck size again. At that point your case run-out should be quite low.

You didn't say how you are reading the neck run-out now. Remember that true run-out, or tilt, is half of the total indicated run-out.

Last edited by boomtube; 11-30-2008 at 03:56 PM.
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  #6  
Old 11-30-2008, 04:12 PM
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Re: Case Cocentricity

Hi Mark
Thanks again for another good reply. I am glad to hear that your process finally worked. After I try a full length sizing if I don't get straighter cases I will go ahead and turn the neck. At this point the neck walls do check very consistant in wall thickness. Following that I will of course Fire the cases and go from there. In the past I did use PFL sizing and got good results. In this case with my new Redding Comp die set I will try to neck size about 3/4 of the neck and then use the body die when needed to get that very slight crush fit I expect that is where I should attain my best accuracy. My goal though is to build some acceptable loads for a PDog hunt this coming year with new brass and that will require a thousand cases at a minimum. The cost savings would be substantial if I can do it with new cases. In addition to the hunting loads I will try to make some real accurate target loads with fired cases. For those I will try to do the "Full Monte" and use all of the methods I can.
Nick
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  #7  
Old 11-30-2008, 04:29 PM
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Re: Case Cocentricity

Hi Boomtube,
Thanks for the reply. I sure hear alot of good things about the Lee Collet Neck Sizer. I don't have one yet but it is starting to look like I am gonna need one. Let me ask you this: Would the Lee Collet Sizer improve the run out on new cases? Would the Lee do better than using the Redding FL die for this straightening process? I know this is just a "one time" deal for me with so many new cases to process. I am sure after the cases are fire-formed the Redding dies will do a good job in making concentric cases.
I have an RCBS Case measuring gauge with dial indicator to do my measurments.
Thanks for taking the time to answer my questions!
Nick
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