reloading for accuracy questions

[tbrice23]

YOU WILL LOOSEN YOUR PRIMER POCKETS BEFORE YOU WEAR YOUR BRASS OUT BY PROPERLY FULL LENGTH SIZING!
Even if it did why in the hell would anyone care about saving brass life at the expence of wearing and galling your bolt lugs!

 

[pdq5oh]

In my search for long range accuracy l've tried many different things. I neck sized for a time and got tired of the hard bolt close and heavy bolt lift after a couple firings. I now full length size every firing. I took a case that fit my chamber tightly and slowly bumped the shoulder back until the bolt closed easily. At that point l locked the die down. All brass is annealed after every firing. The expander ball in my die was carefully polished until l got .002 neck tension. Powder charges are weighed to a tolerance of .04 grain. Bullets are seated within a .0015" tolerance measured base to ogive. Brass is trimmed and mouths deburred and chamfered every firing. Standard deviation runs 4-6 fps with my reloads. I've achieved 1/4-1/2 MOA accuracy and shoot out to 1 mile. I don't weight sort brass as l found no appreciable increase in accuracy for what l do. My thing is long range steel plates. I think very good results can be had by paying attention to details and keeping good notes on what works and on what doesn't.

 

[cajun]

I am new at precision reloading and have been reading a bit before I start to purchase a lot of tools. I was an engineer in the paper industry and understand the importance of concentricity's of bearing fits and can apply this to a bullet spinning down a rifled tube we call a barrel. In order to be consistently accurate all of the concentricity's would have to be perfect from the centerline of the cartridge when chambered to the bottom of the barrel grooves. Pretty hard to measure.

I have read a lot of articles and have a question:
The distance to the ogive of the bullet and bottom of the case (end of the neck) is one measurement.
The distance from the datum line of the case to the bolt face is headspace.
The COAL is the distance from the base of the bullet to the tip of the projectile.

Seems to me that the case should fit exactly into the camber with the neck of the case touching its seat (not sure what this is called yet) and the datum line snug in the chamber. Basically zero clearance for the cartridge to move at all. The ogive of the projectile should be snug and touching the leading edge of the lands of the barrel grooves.

Once this is done I understand that the case should be bumped back .002 or .003 so the fluctuations in ambient temperature will allow the chambering of the cartridge and the projectile should be seated about .005 to .015 (which ever is more accurate for my rifle with load development).

Is this correct?

Also how do I know the neck will extrude to its limit with a fired round -- I assume the pressure formed case will be an accurate image of my chamber but will the neck hit its limit. Maybe the answer is apparent -- would the cartridge separate if the neck does not seat?

Steve Sheasly

Unless it's a rimmed or belted cartridge the round will headspace off the shoulder. The shoulder is what limits forward movement of the cartridge. There is clearance at the neck. How much depends on your chamber.

If your after long range accuracy then pay attention to what the long range F class guys do. Without exception they all full length size. They use either a honed die or a bushing to control neck tension. They use quality brass and many neck turn.They anneal their brass. They weigh charges as accurately as possible. They shoot for a low es. Single digits or low teens. Velocity spread at long range is a killer. Quality brass, consistent sizing and consistent neck tension,powder charges and bullet seating depth. Accurate shooter forum is a good place to lurk and learn. Some of the best long range competitors
are frequent posters.

 

[WalksLikeADeer]

Ok, here goes my ignorance -- ignorance is not stupidity. Stupid cant be fixed with knowledge or experiance, but ignorance can.

Broz used Redding precision shell holders to bump the shoulder back .004 to get zero then .006 bump for the perfect fit for his rifle. He explains that it is fired brass and that you do not want to feel any friction on the closing of the bolt. I agree with him that this would give you a pretty good zero.

But if the bolt will close on a fired brass case, it is fire formed to the chamber so why not just reload and shoot the once fired brass as it is? I do not think you can get a more perfect fit than this-------I am guessing that it is because from experience the brass will stick into the chamber right? If this is the case then why not bump it back one thousandth at a time and fire the rounds until they do not stick? Wouldn't this be the best fit possible? I know I would have to knock the brass out a few times but it should not do any damage to the gun.
But if the idea is to get the cartridge and chamber to fit perfectly as possible this should do it.

 

[WalksLikeADeer]

Steve, to answer your question, the reason we use .002" shoulder bump rather than .0005" is to allow for the variances in sized brass. Some will be a little more, some a little less. This will allow for consistent reliable chambering. Size 10 pieces and measure them with a comparator and you will see what I mean. Trying to set every shoulder back to exactly .0005" would make your engineering mind explode!

If you trim or check length every time, the neck flowing so long that it crimps the bullet in the chamber is not even a thing.

I neck turn new brass after the first firing, anneal every firing, full length size and bump the shoulder with a Redding body die, and neck size with the Lee collet die.

The Lee collet die concentrically sizes the inside of the neck by compressing it against a mandrel giving consistent neck tension. The Redding competition type S bushing die is also a good option and will save a step.

Good luck.You'll figure out what works for you and your application.

 

[WalksLikeADeer]

Ok, here goes my ignorance -- ignorance is not stupidity. Stupid cant be fixed with knowledge or experiance, but ignorance can.

Broz used Redding precision shell holders to bump the shoulder back .004 to get zero then .006 bump for the perfect fit for his rifle. He explains that it is fired brass and that you do not want to feel any friction on the closing of the bolt. I agree with him that this would give you a pretty good zero.

But if the bolt will close on a fired brass case, it is fire formed to the chamber so why not just reload and shoot the once fired brass as it is? I do not think you can get a more perfect fit than this-------I am guessing that it is because from experience the brass will stick into the chamber right? If this is the case then why not bump it back one thousandth at a time and fire the rounds until they do not stick? Wouldn't this be the best fit possible? I know I would have to knock the brass out a few times but it should not do any damage to the gun.
But if the idea is to get the cartridge and chamber to fit perfectly as possible this should do it.

 

[WalksLikeADeer]

Good video!

 

[Snyper708]

Powder charges are weighed to a tolerance of .04 grain.

Have you also tried sorting your bullets by weight?

 

[Barrelnut]

And the bullets bearing surface length?

 

[desertcj]

YOU WILL LOOSEN YOUR PRIMER POCKETS BEFORE YOU WEAR YOUR BRASS OUT BY PROPERLY FULL LENGTH SIZING!
Even if it did why in the hell would anyone care about saving brass life at the expence of wearing and galling your bolt lugs!

I don't know what you guys are doing or not doing that makes you think neck sizing is galling your bolt lugs? It simply hasn't happened in my rifles....

 

[Rich Coyle]

Same here.

 

[pdq5oh]

Have you also tried sorting your bullets by weight?

I used to do that and sort bullets by measurment of base to ogive. I quit doing it because l didn't see any real advantage given my needs. I use the Hornady 147 ELDs in my 260 and find them to be very consistent bullet to bullet. I do measure a few when l open a new box with a different lot number.

Barrelnut. I really have no way to measure bearing surface accurately. I can't imagine there would be enough variation bullet to bullet to be an issue.

I actually have loads that shoot smaller groups at 100 and 200 yds than the ELDs. But at 1000 yds and out the ELDs work better. I think due to the higher BC and heavier weight they retain more velocity and fight the wind better.

 

[Barrelnut]

Barrelnut. I really have no way to measure bearing surface accurately. I can't imagine there would be enough variation bullet to bullet to be an issue.

Yea it's a little nit picky. You need two sets of comparators, like the comparator you use to measure base to ogive. Put one on each blade of the caliper. Put the bullet between them and now it's measuring the bearing surface itself. It is probably the most variable measurement you will find on a bullet. But sounds like it's not necessary on the ELDs anyway. Those are good results.

 

[parker33]

I neck size on my 338 LM and have for over 3000 rounds through a TRG. I push the shoulder .002 whenever I start to feel any type of bolt pressure. It is not uncommon to shoot 1.5" three shot groups at 900 yards. I have a friend who shoots competition and he full length sizes every time. I am going to try some of each and see if there is an advantage.