Been doing this for 50 years, but I still have much to learn.

I want to prep brass for long range accuracy, so I want to form the brass to the chamber. If I seat bullets short of the lands, won't the firing pin push the case forward to the shoulder in the chamber? To blow the shoulder forward, is it necessary to seat bullets to touching or a bit more? I am not trying to "improve" the cases, just get a tight it.

Any advice will be appreciated.
Brice

Yes, that is the way to insure a tight fit; use a medium load; not max since your bullet will be jammed into the riflling. Make the bolt "seat" the bullet.
But I only do that when actually fire forming a case; if your brass fits tightly from the start; no need to fire form it. It depends on how tight you want the cases to fit. I like a slight feel on target loads but on hunting loads I want them loose. You know what I mean.

If both your chamber and your brass are within normal dimensional ranges then no special loading technique is needed. Yes, when the firing pin strikes the primer the case will be pushed forward (if even ever so slightly) until its shoulder rests firmly against the corresponding shoulder of the chamber. In this instance the case stretches rearward until the case head is firmly against the bolt face (this stretching is what causes the pressure ring about a quarter-inch in front of the case head.)
This stretching is minimal if the headspace is reasonably tight, so there is no need to hold the case head with the bullet in the lands.

It is only necessary to hold the case head against the bolt face by jamming the bullet into the lands if your chamber is excessively long (has excess headspace).

Either way is going to force the brass to fit the chamber. If you have a chamber that is on the long side of std and your case is on the short then yes your shoulder will move forward.

Improving is NORMALLY blowing the side so the case out to reduce the taper and often change the shoulder angle.

Using a normal load in a sloppy chamber yes the firing pin will move the case forward. Pressure will then lock the shoulder area down and push the base back to the bolt face. I "FEEL" this thins the brass just in front of the web. Cutting cases apart seemed to confirm but I have NO pictures or measurements.

Using dpcds method the case doesn't move forward but pressure will expand the front of the case to fit the chamber. Moving brass forward if needed. I prefer this method. Other option is to neck up form a false shoulder then use it to headspace.

Where the brass is coming from to fill the chamber is way more critical in a wildcat, IMP etc when you have a lot of chamber to fill.

As I understand you are simply wanting to form your std brass to your chamber then neck size for reloads. In that case form me you are overthinking it. Load and shoot some med+ pressure loads with the cheapest bullet you can find and go shoot them.

Last thought are you sure you and your rifle can tell the difference between new and fireformed as too accuracy?

Thanks for the informed comments. It appears that my assumption about how the case is effected upon firing was not entirely accurate. Perhaps I will do a chamber cast so that I can measure results.

This is all likely overkill for a hunting rifle, but I am helping a friend load for a new barrel and am using the process to help him learn more about the art and science of hand loading. As a result I've had to review my own knowledge and go back to the books. Not a bad thing, esp. when the weather is not so conducive to range work.

Again, I'm gratified with the generosity of fellow AR folks.
Brice

quote:

This is all likely overkill for a hunting rifle,

Way over kill. You are not going to want a tight case for a hunting rifle. Take your factory brass and simply load and shoot it. Then set your FL sizer up to just bump the shoulder. I "feel" that neck sizing has no place on my hunting rifle.

I understand your point, Ramrod and cannot argue with it. I derive some satisfaction from wringing as much accuracy from hunting rifles as possible. To assure reliability in the field I cycle all hunting ammo through the magazine and chamber before heading out. Some loading processes are neither right nor wrong, just personal preference.

Brice, a guy has to do what a guy has to do to make themselves happy.

I've loaded for 45 yrs now. At first I went the neck sizing route testing each round before I went out hunting with it. Have since evolved to the partial FL route. In a good barrel, good chamber I sure can't shoot well enough to see any difference if there is one. Yep I neck sized shooting BR. For my hunting rifle I could care less if the group is .756 or .758. As long as it is submoa everytime it goes out.

Again. Shooting and hunting is a hobbie. You need to do the part of it that makes YOU HAPPY and if someone else doesn't think it is necessary so what.

Also when I had 1 hunting rifle I spent hrs trying to get the group as small as possible. As I got older and more rifles my time has been focused on other things. Good solid subMOA everytime I'm


I would be curious if you have actually comparisons showing that prepping and neck sizing only gains you smaller groups and if so how much. I have since lost most of my data but I know that I could never really say I could. Or does it simply give you that warm and fuzzy feeling that you have done all you could do?

Hi again, Ramrod.
For me, there's the psychological factor which is the confidence that results from better accuracy. In fact, most of the critters we shoot are within a couple of hundred yards and a quarter inch ain't going to make any difference. But, confidence can. I load for the guys in my deer hunting group, and NONE of them shoot or practice much, except for me, of course. I'm the only one who hunts abroad, and when you're going to one of the 'stans on a $30,000 sheep hunt there's no such thing as too much accuracy. As you likely know, 500 yards is not just 5x further than 100 yds, it's a world apart.

All that said, I'm grateful for AR and the opportunity to exchange views with thoughtful and knowledgeable folks like you.
Brice

I've fire formed all my wild cats. Only ONE did I have to jam the bullet into the rifling. Long story!
On a 25-06 IMP I had I fire formed factory 25-06 ammo ! The mechanics of this are simple if you consider that in this case you are dealing with a reasonably slow burning powder. As the pressure increases a good bit of the available energy is being used to move the brass and won't be there to blow up your rifle. roger roger
Never got much of a stretch ring on any of my wild cats. Not that it doesn't happen but it didn't happen to me.

quote:

I am not trying to "improve" the cases, just get a tight it.

I concur with what others have said. You shouldn't need to worry about this unless your chamber is abnormally long or you're fire-forming an improved round to move the shoulder forward.

Firing any regular load (50,000 psi or so) will give you brass that matches your particular chamber. i.e. fired brass is essentially a chamber cast, with maybe 0.001" spring back. Thus you can measure fired brass in various ways and compare with your reloading setup and make adjustments as needed.

This is why some people neck size. So a fired case is a close fit to a particular chamber, and reducing only the neck so it can hold a bullet again gives a near perfect fit as you're describing.

quote:

On a 25-06 IMP I had I fire formed factory 25-06 ammo ! The mechanics of this are simple if you consider that in this case you are dealing with a reasonably slow burning powder. As the pressure increases a good bit of the available energy is being used to move the brass and won't be there to blow up your rifle. Roll Eyes roger beerroger

Exactly! That's why you don't want to slam the bolt too hard when you're shooting loads that are already near maximum pressures as the added kinetic energy transferred to the cartridge will translate to excessive chamber pressures. So always ease the bolt down very slowly when shooting max loads!

quote:

Originally posted by Stonecreek:

quote:

On a 25-06 IMP I had I fire formed factory 25-06 ammo ! The mechanics of this are simple if you consider that in this case you are dealing with a reasonably slow burning powder. As the pressure increases a good bit of the available energy is being used to move the brass and won't be there to blow up your rifle. Roll Eyes roger beerroger

Exactly! That's why you don't want to slam the bolt too hard when you're shooting loads that are already near maximum pressures as the added kinetic energy transferred to the cartridge will translate to excessive chamber pressures. So always ease the bolt down very slowly when shooting max loads!

Stonecreek , this is the only time I can remember that I don't understand you. roger

I'm with Bartshce. How would energetic closing of the bolt affect chamber pressure?