Video On Bump sizing cases.

J E Custom

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This Video does a good job of explaining proper case sizing The way I prefer to size and the reason I think it is more consistent. I realize that many will not agree with it but it has worked for me and proven to be more consistent/accurate for my bolt action rifles.

As many know I do as little sizing as possible to get the best chamber fit and the best bullet alignment without jamming the bullet in the lands and reducing velocity. If other methods work for you stay with them and be happy with the results. If not happy with accuracy you may find this method very helpful.



Just the way I prefer to size cases for loading accurate ammo.

J E CUSTOM
 
Very interesting. When fitting the case to the chamber with the bolt, does the firing pin need to pulled out so you are not feeling the spring tension of the firing pin?

I was taught to pull the firing pin out of the bolt so I can feel no resistance when closing the bolt.

Jason
 
And the majority of competitive shooters bump their shoulders back .001 or .002 so the rifle doesn't move on the bags when working the bolt. Meaning their cartridges have head clearance and you do not worry about galling the bolt lugs from excessive force closing the bolt.

HK76WCp.jpg


Neck sizing also causes excessive force when closing the bolt. Watch the video below by Eric Cortina of Team Lapua USA.



Below your cartridge should fit the chamber like a rat turd in a violin case. The posting below is by Kevin Thomas of Team Lapua USA

Y3IiYL5.jpg
 
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I'm am far from a professional shooter/Reloader, but a few things I found confusing:

He mentions the amount of lube on the case can effect the amount of bump you'll get, yet he lubed the case, sized it and then placed it in his rifle for the "finish sizing" without removing the lube. So didn't he effectively double his negative variable?

He also continues to use the same case and as he mentioned he is work hardening that case and thus will have more spring back with each sizing causing added variables?

He also is using a 3 position safety, shouldn't he be feeling the round with the safety in the middle position thus eliminating the cocking mechanism like you would by removing a Remington firing pin assembly?

Lastly, do we as hunters not want a little play for rain, dirt, dust, spring back, etc etc to make sure that every round chambers in the moment of truth?

I very well could be wrong as I'm a new Reloader, however, I have done a faamount of "testing" as well as research.

Steve
 
Lastly, do we as hunters not want a little play for rain, dirt, dust, spring back, etc etc to make sure that every round chambers in the moment of truth?

Steve

Yes you want a little play and wiggle room on any hunting round, and as the late Jim Hull of the Sierra bullets test lab and competitive shooter said. "The cartridge should fit the chamber like a rat turd in a violin case."

Below German Salizar and from his "The Rifleman's Journal" website that was shut down after Mr. Salazar stopped competitive shooting due health reasons. Please note that Mr. Salizar bumped his shoulders back to allow .001 to .002 head clearance. Meaning his cases were not pushed up against the bolt face and had some wiggle room.

"a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.

In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling."

The Rifleman's Journal
Germán A. Salazar
 
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When sizing a case to fit the chamber I remove the cocking piece and the ejector to prevent any false reading, I also place the case under the extractor before it is placed in the action/chamber.

This is the same method I use when head spacing the chamber.

The reason he placed the case in the chamber with sizing wax on it is something I don't like to do because I don't want any lubricant in the chamber ever. And by using the same case every time without the expander ball is to lessen the amount of work hardening the rest Of his brass. After he finally reaches the best fit he will have to anneal that test case or discard it because of working the brass to many times. but it allows him to reach the amount of sizing desired for all of the remaining cases.

And for your last question, the chamber should not be dirty in the first place but if it does get dusty, the cam action of the action can compress the case .006 to .008 thousandths and chamber the round. Where some actions cant/wont function dependably with out clearance. If you are shooting dangerous game, this is something that is normally allowed for with full sizing and neck clearances up to .004 thousandths per side. But we are talking about accuracy loading so the rules are different depending on the use and the type of firearm used. the better the fit generally the better the accuracy but the more difficult chambering in many types of actions. so the shooter has to decide what he wants and excepts.

Fortunately, bolt actions are more forgiving in many ways that other actions aren't. But generally they are the most accurate system.

I find ways to keep my rifles clean even the worst conditions so I know I can rely on there functioning when I need them, so with that in mind, the loading procedure is different for different rifles I hunt with.

J E CUSTOM
 
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Just something to think about. Why go to all the trouble to blueprint an action. load concentric ammo and feed it sloppy fitting cartridges. Also when fire forming an AI cartridge it is common place to have a .004 to .006 negative head space that Places the bolt in compression? it is to hold the cartridge so there is no forward or backward movement during fire forming and producing accuracy that many times exceeds the accuracy of a cartridge that Is full sized for a standard chamber and has "Slop In the chamber fit".

Many Improved cartridges will shoot 1/2 MOA groups while fire forming even though the case is re forming to the chamber shape It cannot move forward stays on the centerline of the barrel bore and has no head space what so ever.

That is why I feel that doing minimum sizing for accuracy in bolt actions to assist the bullet in perfect alignment of/with the bore can only help. Full length sizing and bumping the shoulder
may make it easier to chamber and definitely easier to load but it is counter productive to all the care and precision work that goes into blueprinting/truing and action and turning necks and loading quality concentric ammo.

I full length sized for many years while competing and was happy with 1/2 MOA, but when my priority became extreme accuracy for extreme distances, I had to improve everything associated with the firearm, quality, loading and shooting proficiency. Now My starting accuracy standard is
less that 1/2 MOA with the goal of sub 1/4 MOA or better and if I manage to get everything right sub 1/10th MOA. I feel this level of accuracy is necessary if you intend to shoot extreme distance. If you hunt 3 or 400 yards this level of accuracy is definitely not required so do what is best for your needs.

J E CUSTOM
 
I ditched my FL sizing because I had to check each case to fit and function as I use my guns for hunting and can't have anything but a smooth proper bolt function. I also noted that about 50 out of 100 cases, once fire formed and neck sized twice, would need to be FL sized or would not feel the same when chambering. I talked to Norma a few years back about load information on the 338 NM I was in the process of building and they gave me the advice of a 0.002 bump with FL sizing only. I've also galled bolt lugs due to tight head spacing by accident. Once I figured out it was a head spacing issue, I started to monitor more aspects of case sizing.
 
1 MOA accuracy Is easy to obtain, 1/2 MOA is much more difficult, 1/4 MOA becomes many times more difficult and sub 1/4 MOA requires that you pull out all the stops and leave no stone unturned.

So reaching this level of accuracy requires that all processes be the best that can Including the shooters skills. It is what I call a package deal.

In many cases this level of accuracy is not necessary to many and not needed for others types of hunting and shooting so it becomes a personal goal. :)

J E CUSTOM
 
This Video does a good job of explaining proper case sizing The way I prefer to size and the reason I think it is more consistent. I realize that many will not agree with it but it has worked for me and proven to be more consistent/accurate for my bolt action rifles.

As many know I do as little sizing as possible to get the best chamber fit and the best bullet alignment without jamming the bullet in the lands and reducing velocity. If other methods work for you stay with them and be happy with the results. If not happy with accuracy you may find this method very helpful.



Just the way I prefer to size cases for loading accurate ammo.

J E CUSTOM

thank you
 
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