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Neck Sizing

 
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  #8  
Old 07-13-2013, 08:42 PM
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Re: Neck Sizing

Quote:
Originally Posted by Mikecr View Post
Forget what BR shooters do.
They don't shoot 270Wins in competition, and YOUR best neck tension would be determined by YOUR load development(not theirs).
I agree. You will not get better bullet seating concentricity by only sizing 1/8 in a standard neck clearance chamber. The BR shooters may do that because the neck is a tight neck chamber and it does not expand much so the amount of resizing is very minimal .
You can do a partial neck sizing operation in any standard factory chamber but you need to size down 3/4 of the length of the neck to make sure you have enough length to align the bullet and neck tension to hold it. A long neck case is good for this operation.
BR shooters gently feed one round at a time by hand it's a different situation to hunting and normal shooting using magazines etc. and big kickers .
Forget using a standard full length sizing die . Buy a Lee collet die and put a washer over the case on top of the shell holder this will shorten the length sized and allow a slight extra shoulder for better alignment.
If the extra shoulder makes chambering a bit tight , size down the neck lenght more until it chambers nice.
However a very slight crush as the bolt closes is ok as it usualy dissapears after first firing and you have a nice minmum headspace case. It varies with different chambers and case designs.
However to preserve this slight shoulder you need to buy a body die to size the remainder of the body .
Using a standard type die to partial neck size is always a risk that on extracting the case the friction may pull the shoulder out and prevent easy chambering .
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  #9  
Old 07-13-2013, 11:01 PM
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Re: Neck Sizing

Shooting a 30-338 over here.
I am using .338 brass and the RCBS FL die set in the 30-338 cal. I too would like to maintain the first fired chamber size on the brass and do only a neck resize.
I am not real good at understanding books and directions, I was readfing ther instructions on how to set the die to accomplish only the resizing of the neck but, I just could`nt get it from My eyes to My brain, as to what it was telling Me what I needed to do.
Western Powders is less than a mile from My house, I think I will go and visit them. Most helpfull people they are.Once I see it, then I am OK to do it.
I mechanicked since I was nine, bneing in solvents and chemicals for over fifty years, I dont think, has helped My ability for the read then do exercises.
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  #10  
Old 07-14-2013, 10:15 AM
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Re: Neck Sizing

Sierra Bullets has got best accuracy by full length sizing all their cases used to shoot their bullets for quality control. Same for load development in factory rifles shooting their bullets. They've been doing it since the 1950's.

Best results are with dies whose neck diameter is a couple thousandths smaller than a loaded round's neck (no expander ball used) and its sized all the way back to the shoulder. The fired case body is sized down a bit and the fired case shoulder's set back a thousandth or two. If this ain't done correctly, then such full length sized cases may well not shoot as well as neck only sized ones; expecially when the fired case shoulder's set back way too far.

Note that bottleneck cases headspacing on their shoulders center perfectly in the chamber when fired regardless of how much clearance there is between the case body and neck to the chamber in those areas. It's the case shoulder that centers the case up front in the chamber shoulder, not the body or neck. Case necks float clear of the chamber neck regardless of clearance and are very well centered there if they're well centered on the case shoulder. Case body's are clear of the chamber wall except for its back end at the pressure ring where the extractor pushes it against the chamber at that point.

Neck only sizing dies do not center case necks on case shoulders as well as full length sizing dies do. This is why most benchresters now full length size their fired cases, but only a minimal amount. Their smallest groups didn't get any smaller but their largest ones sure did.
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  #11  
Old 07-14-2013, 07:38 PM
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Re: Neck Sizing

Quote:
Originally Posted by Bart B View Post
Note that bottleneck cases headspacing on their shoulders center perfectly in the chamber when fired regardless of how much clearance there is between the case body and neck to the chamber in those areas.
If only it was that simple but it's just not. If this was true in every case then a standard factory chamber should be able to win any BR competition and it just can't . If the body is loose then the shoulder can only centre perfectly if the case is an almost crush fit . Some shoulder angles are better than others . Most re-loaders can't size accurately enough to get that perfect no head space fit so the tighter neck makes up for that no matter if the shoulder is that tight fit or not .
I have proved partial neck sizing works over and over again in a factory chamber since 1967 when I invented my first body dies but I have also seen a few guns that it did not work in .
The term full length sizing when used in connection with BR shooters is miss leading because what they do is size so slightly that it does not upset the case fit and reloading speed is also a factor for them.
That can not be compared to using old fashioned Full Length dies with expander balls that totally upset the case fit .
It is not possible to make blanket statments when talking about factory guns because variations in manufacture can make one gun work well with something and another not .
People should try all ideas and see what works for them because one size does not fit all .
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  #12  
Old 07-14-2013, 11:00 PM
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Re: Neck Sizing

Bumper Bullet
You have turned on a whole new light in My reloading practices.
So now, I guess the main concerns would be to.
1. remove the expander ball
2. measure the shoulder, before and after resizing to, see how much My settings is altering the shoulder.
Would this be correct, if I was wanting to get maximum accuracy out of My reloads ???
Or, maby the RCBS dies I have would not even be suitable for this type of F.L. resizing.
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  #13  
Old 07-15-2013, 05:17 AM
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Re: Neck Sizing

By neck sizing down to about .010" of the neck-shoulder junction, you leave a small but larger than diameter ring on the case which will bump against the chamber leade when seated. This will help center the bullet, i.e., better accuracy. ,
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  #14  
Old 07-15-2013, 05:39 AM
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Re: Neck Sizing

I think this thread is going to be very confusing for anyone new to reloading. I am going to add some explanations that hopefully will help.

First of all I suggest to anyone who is new to this activity to acquire a Nosler or Hornady reloading guide and read the chapter on hand loading.

Most beginners do quite well with standard factory two die sets that have a full length (FL) sizer and a seater die.

The concept of sizing the brass is twofold. The necks expand to release the bullet so they have to be reduced in diameter(sized) to hold the next bullet. The body will lengthen and expand in diameter to conform to the chamber. There is some spring back after initial expansion so the brass can be removed from the rifle's chamber but some reduction in case dimensions (sizing) may be necessary for the case to easily fit back into the chamber. This is especially important with an autoloading rifle. If the case is too large the auto won't function properly.

Typical FL dies are designed to accommodate cases made by different manufacturers. Cases vary in neck wall thickness. The upper part of a FL die is made small enough to size down even the thinnest production case. This requires a sizer ball to open up any case neck so that the inside diameter will allow the seating of a bullet. The typical inside dimension of a FL sized case neck is .003" smaller than bullet diameter. This is a compromise in neck tension which usually works well with rifles that will hold some loaded rounds in a magazine. If the tension is too loose recoil could cause the bullet to move in the case.

Removing a sizer ball from a FL sizer die and sizing any part of the neck would make it too tight with even with the thinnest production brass. If a loader were to try to seat a bullet the stresses on the case would cause it to deform creating excessive runout or in simpler terms cause the bullet to be crooked in the case. The bullet would then enter the rifling uncentered and deformation would occur. This would cause inaccuracy.


Setting up a FL sizer can be confusing. RCBS's literature says to screw in the die till it touches the shell holder. While this would work the brass is usually sized too much. This will "overwork" the brass and with the next shot the brass will lengthen to fit the chamber. Repeated sizing in this manner will cause the cases to lengthen so they have to be trimmed often. Eventually the brass will thin out just in front of the web area causing case head separation. The best approach is to PARTIAL FULL LENGTH size. This is accomplished by turning the die several turns away from the shell holder and sizing the brass. The brass will most likely not fit easily in the rifle chamber. Lower the die part of a turn and repeat. Continue to lower FL die till it sizes the brass enough for either a fit with slight bolt closing resistance or one that allows you to close the bolt without resistance but no more. There is a fine line between the two settings. Once you find that spot you can repeat it by using feeler gauges to measure the gap between the shell holder and end of die body. I like to keep those feeler gauges in the die box for the next time I setup. Some loaders prefer to set the lock ring but sometimes they can move on the die. Your choice.

There is a term that was thrown around in the first few posts called partial neck sizing. I think that was accidentally altered from the usual practice called partial FL sizing. I have been handloading for almost 30 yrs and never heard of partial neck sizing.

Bushing dies do not size all of the neck. A small portion of the neck just above the shoulder remains untouched. This might be considered a partial neck sizing but that is the nature of the die in the way it works. I have not read of anyone adjusting a bushing neck sizing die to only size part of the neck but I suppose someone has tried it.

If a beginner wants to use a bushing die then there are two types. One is called a bushing die the other a FL/bushing die. The FL/bushing die makes the process easier but it might not serve the user as well as separating the neck sizing from body sizing. As was mentioned above there are body dies that will only size the body. This style of die reduces body taper and can move the shoulder back for easy chambering just like the FL die.

I wrote the above to help anyone new to handloading. There is much reading to be done and questions to ask. Many of us here are very willing to help others learn this fun and rewarding activity. Hope this helps.

Ross
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