Re-size question

[NorCal67]

Excellent thread for someone who's only been doing this for 6 or 7 years, and self taught from the internet. Thanks men.

 

[bigedp51]

You can't fire a case several times and just neck size for pump actions, lever actions and semi-autos if you want the cases to extract. And you sure as heck will not fire and neck size a case 2 or 3 times in a AR15 without it jamming.

In a semi-auto the resized case body diameter should be .003 to .005 smaller in diameter than its fired diameter. This ensures the case springs back from the chamber walls when fired and extracts reliably.

Below three types of Forster .308 Winchester dies.

The basic thumb rule for shoulder bump is .001 to .002 for a bolt action and .003 to .006 for a semi-auto.

But below these .308 Win cases were full length resized with the die making hard contact with the shell holder. And fired in a new Savage rifle without adjusting the die for minimum shoulder bump.

Below we do not have the amount of head clearance these cases had, but the top Nosler case did not start to stretch until the 8th firing. And the bottom Norma case did not stretch until the 18th firing.

 

[MNbogboy]

You can't fire a case several times and just neck size for pump actions, lever actions and semi-autos if you want the cases to extract. And you sure as heck will not fire and neck size a case 2 or 3 times in a AR15 without it jamming.

In a semi-auto the resized case body diameter should be .003 to .005 smaller in diameter than its fired diameter. This ensures the case springs back from the chamber walls when fired and extracts reliably.

Below three types of Forster .308 Winchester dies.

The basic thumb rule for shoulder bump is .001 to .002 for a bolt action and .003 to .006 for a semi-auto.

But below these .308 Win cases were full length resized with the die making hard contact with the shell holder. And fired in a new Savage rifle without adjusting the die for minimum shoulder bump.

Below we do not have the amount of head clearance these cases had, but the top Nosler case did not start to stretch until the 8th firing. And the bottom Norma case did not stretch until the 18th firing.

Quite the test? Who conducted this and to what expense? Plainly shows how oversizing causes head separation.

 

[243winxb]

Full length sizing die adjustment, without a gauge , for bolt actions. Bottle neck cartridge like a 243 Win.

Leave the bolt as is, ready to fire.

Back Fl die off shell holder .010" , size, see if 3 pcs of brass will chamber in rifle.
1. If empty brass chambers, load and fire. Repeat sizing till bolt closes with a crush fit. Then bump shoulders back a bit. Check gap between shell holder and die with a feeler gauge. Adjust die down.

2. Brass will not let bolt close- Check gap between shell holder and die with a feeler gauge. Adjust die down a bit.

Old method from the dark ages.

 

[Rich Coyle]

I'm almost 75 and never heard of the feeler gauge idea. I partially size a case so it's too long and try it in the chamber. Of course it won't fit. Then size the case a couple thousandth at a time till it fits.

 

[MNbogboy]

When I think I have it right, a single piece of scotch tape (.002) on the case head should make a very snug fit in the chamber. Measurements of a fired (snug) case and the sized case will have about .001-.002 difference.

 

[300jcc]

Just to be clear, the OP was asking about bumping for his bolt gun. I gave no consideration in my post in re: semi-autos. Different animal altogether.

 

[bigedp51]

This is the "Long Range Hunting Forum" and not "Benchrest Central". And I have hunted and been caught in freezing rain and snow. And in freezing weather when you fire a round you can get condensation in the chamber that freezes immediately. I have had this happen and the next round chambered you hear the ice crunching and the round is hard to chamber, if it does chamber and the bolt closes.

There is nothing wrong with giving the cartridge some wiggle room to insure it chambers under any condition when hunting. If you are making up a new load with new brass and start at the suggested start load and working up your fired cases will be different dimensions. So how many times are you going to fire the cases before you actually hunt with them.

The average hunter who reloads does not need to reload to benchrest standards. And I will always remember what the late Jim Hull said who worked in the Sierra ballistic test lab and was also a competitive shooter. "The cartridge should fit the chamber like a rat turd in a violin case." And I'm saying this because I have had brand new cases that were .009 shorter than my GO gauge.

Click on the image below to enlarge and read what Kevin Thomas of Team Lapua USA has to say and who also worked in the Sierra test lab. And he also states that their loaded test ammunition had to fit in a variety of different firearms.

 

[MNbogboy]

This is the "Long Range Hunting Forum" and not "Benchrest Central". And I have hunted and been caught in freezing rain and snow. And in freezing weather when you fire a round you can get condensation in the chamber that freezes immediately. I have had this happen and the next round chambered you hear the ice crunching and the round is hard to chamber, if it does chamber and the bolt closes.

There is nothing wrong with giving the cartridge some wiggle room to insure it chambers under any condition when hunting. If you are making up a new load with new brass and start at the suggested start load and working up your fired cases will be different dimensions. So how many times are you going to fire the cases before you actually hunt with them.

The average hunter who reloads does not need to reload to benchrest standards. And I will always remember what the late Jim Hull said who worked in the Sierra ballistic test lab and was also a competitive shooter. "The cartridge should fit the chamber like a rat turd in a violin case." And I'm saying this because I have had brand new cases that were .009 shorter than my GO gauge.

Click on the image below to enlarge and read what Kevin Thomas of Team Lapua USA has to say and who also worked in the Sierra test lab. And he also states that their loaded test ammunition had to fit in a variety of different firearms.

I also agree on this one. Not only frost & ice but dust & dirt carried by the wind in a lot of our western hunting conditions. I've had snug neck sized loaded ammo in one of my 260s almost fail to extract easily after a few hour sit on a mountainside in the Wyoming dust bowl. Chambering tight ammo in a dirty chamber not only difficult but actually hard on the chamber and brass.
Full length sized with minimal bump is all I care to hunt with now (especially in windy dusty conditions).

 

[Mikecr]

I think there were good points brought up with FL sizing. Just keep in mind that we don't all do it in every case. And we don't all drag our factory or custom hunting guns through mud.

You can setup a gun to operate just fine with NS only, or even fitted for no sizing need whatsoever. But it won't be a sloppy design, sloppy build, with a sloppy chamber, and an old *** cartridge (designed for sloppy). None of this would be in the plan.
With appropriate build and standard load development, you can make a non-FL sizing gun shoot as good or better than it would while FL sized.
The qualifier here is the PLAN.

 

[bigedp51]

I think there were good points brought up with FL sizing. Just keep in mind that we don't all do it in every case. And we don't all drag our factory or custom hunting guns through mud.

You are correct, I didn't carry my Remington 700 with its Leupold scope in bad weather. I carried my 1943 Remington 03-A3 30-06 rain gun with a cut down stock a peep sight and its fat long military chamber. And the cases were full length resized with the die making hard contact with the shell holder.

In my opinion far to much of what benchrest shooters do filters down to hunters with off the shelf factory rifles. Example using bushing dies when the Redding FAQ tells you if the neck thickness varies more than .002 to use the expander. Or telling you if you reduce the neck diameter .004 or more with a bushing die you can induce neck runout. And if you do not have a custom tight neck chamber you will be reducing the neck diameter far more than .004.

 

[25WSM]

Here is something nobody has mentioned to you. First I am a gunsmith with over 30 yrs under my belt. I build more target rifles than hunting rifles. I currently shoot 1000 yd benchrest. So here is something that will keep you out of trouble. I measure my setback to .001 to .002. You can go .005 with no issues. The current world record holder at Williamsport sets his back .008. So once I am at the .001 to .002 I will take my bolt apart firing pin and extractor. Then I will see how they feel when chambered. Ideally the bolt will close with no friction at all. So here is where guys get into trouble. They don't measure the set back first. If you only go by the feel method you can end up setting your cases back way way to much. Here is why. For the case to fit so the bolt closes with no friction the shoulder has to be pushed back AND the shoulder body junction and entire body of the case has to get smaller than the chamber dimensions. So if you have a sizing die that is slightly to big in diameter the body will be to large to chamber without friction. The to big die will still set the shoulder back. So basically if your only using the feel method you would keep setting the shoulder back more and more and more and it's still got friction because the body doesn't fit. To round this up it goes like this. Set your brass back with a guage to .002 . If it has friction at that point your die diameter is to big around. And setting your shoulder back ten to twenty thou won't make that friction go away. You need a die that will reduce the body diameter also. If you want a truly great book get the one from Ratigan. He explains this in more detail than me with pictures too. Well thats it for me. Long live long range. Shep

 

[Mikecr]

It's a god awful body die that would allow or cause any part of a case to get wider. I believe it's possible, but have never run into it.
I bump shoulders ~1-1.5thou. If there is a nuet's breath of friction in this, perhaps a slight angular delta, I don't care.

 

[300jcc]

Once again, I suppose I need to clarify. I'm not a benchrest shooter, never have been. The original OP was asking about shoulder bump. If his question was, "I'm going out hunting with a pack of crackers and my rifle and I need to shoot something to eat - how should I do it?" then that would be different. I realize what forum this is. Making long shots = making long shots. If we don't share ALL of the information we have about a subject, why post? I realize that folks may simply be sharing their concern for CONDITIONS that might affect how one goes about determining their setback, and that's wonderful. However, I'm trying to offer insight into some advanced loading techniques that MIGHT be useful to the OP now or at some other time. I didn't qualify conditions and I certainly didn't mention benchrest or hunting frozen tundra. OP - as you can see, everybody has their own way of doing things. 99% of us end up at the same place when the variables start flying. You will learn how to load what and when as conditions arise. Just read the different techniques and determine for yourself what you want to try, WHY, document your results, keep what works for you and disregard what doesn't. Adjust for conditions. Lather, rinse, repeat.