Shoulder bumping

davidu

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Just like most things,there are ok/good sizing dies and there are better sizing dies.
I’m not sure what brand the OP uses, but I highly recommend the Forster. I’m sure there are other very good brands, but
I would recommend the Forster fl sizing die. Then have Forster hone the die based on their sizing chart once you’ve sized the brand of brass typically shot. I AMP anneal every time and find there’s very little runout and a consistent 2-3 thousands shoulder bump is easy to achieve.
 

BoomFlop

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@RAGGED EDGE

If you are going to do it the way Broz does in the video, you will need to remove the firing pin assembly as well as plunger. Otherwise, the side pressure the plunger puts on the case will make it very hard to feel for interference and your bolt will not drop on its own.

Hope this helps.
 

Marine sniper

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Couple thoughts:

I have tested SB related to accuracy extensively, and while it sounds good to have as little as possible- it is entirely irrelevant for anything less than bench rest accuracy. I am as anal as anyone when it comes to things like this and my primary hunting rifle (a custom 338 Ackley Lapua with a 40* shoulder is set at .0045 to .005 SB.

The proof of the irrelevance of SB being at all related to accuracy is how often do you have fire forming loads that are really accurate? It is silly to be worried about the difference between .002 or .005 jump when fireforming loads sometime have .200+ jump. Is there any other part of reloading where such huge spreads can still result in very good accuracy? Nope....

Number of firings on brass will change SB slightly (even after FL sized) freshly annealed will be more consistent because of the work hardening someone else mentioned.

More so than SB / annealing effects neck tension which has more influence on accuracy than SB.

To measure the actual SB properly you need to remove the firing pin and ejector. Removing these pieces is also the only way to know your actual bullet jump.
 

Taylorbok

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The point of .002 bump is to not work your brass as much and provide a more consistent chamber pressure from firing to firing resulting in more consistent sd/es. You could set your shoulder bump more or less what ever but consistency is the key.
 

vancewalker007

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A set of shims can help. Put a .001 or .002 on top of the shell holder and screw the die down on top of them till it is tight. Tighten the lock ring, size the case, and then measure and see if you get the desired result. You may want to start with an annealed case to prevent any brass spring back. To prevent case stretching keep the sides of the case well lubed.

I have heard that for hunting rifles .003 setback may be preferable, anybody know if that is the case?
The typical dogma is .002 bump because this will give most cartridges enough clearance to chamber smoothly and still be tight enough for the firing pin to work reliably. Its a very good starting point. There are instances where more bump is needed. In my 6.5 PRC I found a .004-.005 bump pushed the case into the die enough to fix the clicker issue where the 0.2 base datum line was not resizing enough. With this bigger bump the datum line went from .533 to .532 and now all my cases chamber like new cases and the shoot fine.
 

Marine sniper

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The point of .002 bump is to not work your brass as much and provide a more consistent chamber pressure from firing to firing resulting in more consistent sd/es. You could set your shoulder bump more or less what ever but consistency is the key.
I have found no correlation between SB / chamber pressure and ES/SD. That said, I prefer the .002 over .005- but in the end I do not think it matters at all even when the work hardening issue is factored in. Does an extra .003 stretch really matter? I highly, highly doubt it.
 

QuietTexan

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Well what do you lose first, the primer pockets or the case heads? If it's the pocket, then no harm no foul, bump 0.005" and be happy - maybe consider dropping to a slower node if you don't need the extra FPS because why tear up good brass for no benefit. If you're getting a case head sep on the tenth loading, sizing might be a problem. If you're getting case head sep on the third loading, sizing is definitely a problem. If it's the necks splitting, start annealing and find out what the real limiting factor for the case is.
 

nksmfamjp

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I anneal my cases by putting them in a shallow pan of water and using a propane torch heating the top of the case a dull red and tipping them over in the water. It makes resizing them much easier is there a better way?
Any of the automated flame annealers like the Annealeez will be more consistent.

I have heard that for hunting rifles .003 setback may be preferable, anybody know if that is the case?
I like to size until the bolt handle drops plus about 0.001”. I think that was fired minus 0.004” in my 300 Sherman. In my PPC, that is like fired minus 0.002”.
 

FEENIX

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Have a machinist shorten the die.
A competition shell holder set is perhaps the easiest, most convenient, and will give more versatility; you can still use it for other dies/cartridges. For instance, if you get one for a .532", you can use it for .300 WM, .300 WSM, 7MM RM,264 WM, etc. The competition shell holder set might also be more economical versus the minimum set-up fee and charge for a machinist/gunsmith ($50-75/HR depending on area)—just something to ponder.
 
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