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Discussion Starter #1
It is said if you can get your brass to fit your chamber with a minimum amount of clearance accuracy is better. This makes sense but it seems I often have the cases vary a considerable amount when I resize them and check the shoulder length with a comparator. Anyone else have this happen and what is the reason and is there anything that can be done to get them all more uniform? I realize it is not possible to have them all exactly the same but it would be nice to be close.
 

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You have to start with consistent cases , purchase new brass from one maker , full length resize , load the brass and fire all in your rifle . Trim the brass to a consistent length and now you have consistent brass that fits your chamber... a bolt action works best ... semi-auto rifles are another story .
After the next firing neck size or "bump size" all the cases so they just chamber in your rifle with slight bolt resistence .
The trick is starting out with brand new consistent manufactured brass ... mixed headstamps and range pick up brass fired in other rifles isn't going to yield consistent results .
Gary
 

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It is said if you can get your brass to fit your chamber with a minimum amount of clearance accuracy is better.... is there anything that can be done to get them all more uniform?
This a true statement, the better you case can fill the chamber, (body and shoulder) your accuracy "should" improve provided your're doing everything else in the way of case prep right. The idea is to have the bullet resting in the chamber in a straight line with the bore axis, so when it's fired it hits the lands in a concentric fashion, not like throwing a marble down a 2" tube.

First question......Are you sure you need to "bump" the shoulder? If you can take a FIRED case and chamber it and close the bolt with NO effort, the answer is no you're not there yet. If you have difficulty closing your bolt on a fired case, in other words a tight or stiff bolt, it's time. If you're not there yet you can adjust your F/L die to only work the neck without working the body allowing the shoulder to move forward to it's most forward position, then it's time to bump.

Here are two of the most common reasons for inconsistent shoulder bump readings........The level of "work hardening" of the brass. Do you anneal? Without annealing every piece of brass it will have a different level "spring back" which will change your datum numbers from piece to piece. Case lube is another reason, how are you lubing your cases? Consistent application of case lube is paramount, variations in how the case lube/how much lube applied will make a difference, I find a "spray" lube will produce a better level of consistency than using a pad or applying with your fingers.

What can you do to help get more consistent readings? Anneal your cases prior to bump sizing, (check out post #99 in the "Help New Reloaders" thread, I laid out how to anneal with tools you probably already have on hand). If you don't anneal you won't get consistent shoulder bumps OR consistent neck tension, both are accuracy killers. Make sure your dies are clean, increase the dwell time for your cases when the ram is up, (try 5 to 8 seconds), lower your ram, rotate the case 1/3 of a turn and repeat. This should help to get your numbers closer together.
 

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The trick is starting out with brand new consistent manufactured brass ... mixed headstamps and range pick up brass fired in other rifles isn't going to yield consistent results .
Gary
I don't totally agree with your statement Gary.............IMO it doesn't matter if its new or old provided it's been fire formed to your chamber at some point and of the same MFG............But.......Bumping sizing various headstamps present another issue due to case capacity, they may or may not be the same. You could have the same shoulder push-back but variances in case capacity could mean two different levels of accuracy down range.
 

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Discussion Starter #5
This is all with Winchester brass and it has been annealed, although I am not positive on how good the job as. I might not have gotten it hot enough since I hear if you get it too hot it is ruined. I am quite sure the first batch I did was not right but the second time I think I got an acceptable job. I trim the brass also but this is another area there seems to be less precision than I had hoped for.

I think some calibers are worse about shoulder length increases also. The 243 only takes a few firings before you feel resistance on the bolt. The 223 has been fired more total times than the 243 and I have yet to full length resize it. This could be due to other things, such as the chamber being loser but I am pretty sure I read the 243 is kind of noted for this. The 22-250 seems to be between the 223 and 243 for the problem, at least that is my experience. It might have something to do with the quality of the brass, I have no idea. I did get Lapua brass for the 223 which is supposed to be excellent.

I lube the cases with Hornady unique case lube. This is another area where I learned something very quickly. When they say lightly lubricated, they mean LIGHTLY. I dented several cases when I first started but have now got that eliminated. They weren't dented to the point they were trash but it is better not to do it.

If I don't have to FL size I use the Lee collet neck sizer. I have heard good things about it. I can't say it has improved the accuracy of the 243 but it is such a disaster it would be hard to tell. With the best possible bullet I have found it is probably about a 1 MOA gun on average. I have shot some better groups but also worse, although not a lot worse with the correct bullet. With heavy bullets it is terrible.
 

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The shell holder & fl die must make contact when sizing. A set of Redding competition shell holders allowes this.

The contact removes any spring in the press & slop in the linkage.
 
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