Dave Scovill and Run Out

[Vacek]

I hope I am wording this right.

In several of Dave Scovill's editorials in Rifle and Handloader he gives more credence to minimum run out versus seating the bullet just off the lands when it comes to precision.

That being said, to minimize runout are the straight line are the Wilson Chamber Type Bullet seaters and/or the Lee Dead Length seaters or similar products the best way to go?

Any thoughts regarding run out vs seating off the lands?

 

[ranger335v]

You know what low runout accomplishes, you may not know what seating depth accomplishes. First, if the bullet is straight, seating to the lands does virtually nothing to bullet alignment and not much if it isn't straight. What seating long, close to the lands, can do is raise start pressure and seating deeper - long bullet jump - actually decreases peak pressure for a given charge. Experimenting to find the best balance of start and peak pressure assists consistant combustion and that can improve accuracy but only IF the bullet's muzzle exit timing is correct; otherwise accurscy will be consistantly poor even if your velocity Extreme Spread is zero!

Bottom line, we simply can't honestly say what seating deep or long will accomplish. Or what changing bullets or powders in the same rig may - or may not - do to change the best jump to the lands. Simplicity simply isn't to be found in this game, there are no rules we can depend on except ONE; we must 'try it' if we want to know what something will do. That includes any potential difference different seaters may produce. I don't think a Wilson type seater does a thing until groups are consistantly in the quarter MOA range and that's a LOT less common than some web BS suggests. Lee's Dead Length seaters, used correctly, are much better than many seem to believe. Few factory rifles gain much from Redding/Forster seaters and they are the best of the threaded dies. IMHO.

 

[Walkalong]

Concentrically is very important for extreme accuracy, but finding the jump, or lack thereof, that your rifle likes can make a big difference as well.

 

[Vacek]

So with my Savage 308, using the Lee Dead Length Seater properly, I should be good to go. This is for a 130 grain Nosler Ballistic Tip behind 44 grains of Varget. This is my basic go to load for deer and antelope.

 

[helotaxi]

I don't particularly like the design of the dead length seater die, the size die is just as, if not more, important than the seating die in getting minimal bullet runout. If the neck is pushed/pulled out of alignment with the body of the case, nothing that you do with the bullet will fix that. As far as seating dies go, I like the "chamber style" seating dies like the Forster or RCBS competition dies. It uses more than one reference point on the case to align the bullet, unlike the Dead length. The other designs also give you a lot more latitude in seating length. I've also had problems with the Lee die having the bullet hang up in it sideways while that is essentially impossible with the other designs.

 

[kelbro]

Low runout is never a bad thing. Low runout + seating just into the lands works well too. Where the differences show up is in a rifle with a nice chamber and perfectly trued bolt face.

Doesn't matter how straight your loaded round is if you have a sloppy (many factories) chamber or the bolt is not holding your cartridge perfectly square to the barrel. Seating just into the lands can help compensate for some of that.

A good gauge of the chamber concentricity is a once or twice fired case. Measure it before sizing to see what you are working against.

 

[918v]

Here's the problem with runout:

Say you have a perfectly concentric round with zero runout. Being the chamber is looser than the round, the round will be laying on the bottom of the chamber. This will point the bullet up in relation to the bore center. If you have a match chamber, then this issue is minimized because the chamber is so tight the angle of the bullet v the bore center is nill. If you have a standard chamber, that angle is more substantial. If you have a machinegun chamber, the angle is even bigger. So the bullet will enter the bore crooked.

So people try to mitigate this and neck size. This centers the case in the chamber and allows you to concentrate on concentricity. But then you may run into neck issues. Every case is unique. You can get the best dies ever and the best brass ever, but that does not guarantee concentricity.

It is not the seater that makes concentric rounds. Any seater can. It is the neck die. I found, through testing of different dies, that the less you size the neck the more concentric the round. So if you have a standard chamber that allows the neck to expand .010", then going for zero runout is like chasing unicorns.

I also found that, at least in factory chambered 22 centerfires, the Lee Collet Neck die gives better results than bushing type dies.

Don't get your hopes up for anything better than +\- .002" if you are resizing for a factory chamber.

Just being real.

Now, you can get a Hornady runout tool, but the only way you'll be able to fix your rounds is if you only size half or less of the neck. The bullet has to be able to pivot inside the neck for the tool to be able to adjust it. That in itself poses a bullet setback problem for semi autos.

Sometimes it is just better to load 100 rounds, pick out the best ones for punching groups, and use the rest for shooting plates.

Concentricity can be frustrating. The reason benchresters don't worry sbout it is their chambers are so tight they don't even size their necks. They rely on brass springback to hold the bullet in place tight up against the rifling. The freebore is prolly .0002" larger than the bullet, so there can't ever be any misalignment. You cannot have these same expectations with your factory rifle. Anyone who tells you otherwise is lying.

 

[Walkalong]

While I was actively shooting Benchrest, some shooters turned the necks for tight necked chambers so they did not have to size necks, but most did not cut it quite that close, and sized the necks. I had less than .001 clearance all the way around, and I (partially) sized necks. We sized minimally for light neck tension.

It is true the case needs to be aligned with the bore when the cartridge is fired. This can be accomplished a couple of different ways. This is another reason "Match" chambers are tighter overall than standard chambers. Then of course there are the "tight necked" chambers which go another step.

Perfect runout by its self is not all that is needed. A nice straight cartridge in a sloppy chamber isn't going to work well.

 

[Slamfire]

In several of Dave Scovill's editorials in Rifle and Handloader he gives more credence to minimum run out versus seating the bullet just off the lands when it comes to precision.

I would give more credence to Dave Scovill's rants if he was a competitive shooter.

You cannot compensate for poor shooting skills with expensive equipment and esoteric reloading habits.

 

[Walkalong]

I would have to agree.

 

[918v]

While I was actively shooting Benchrest, some shooters turned the necks for tight necked chambers so they did not have to size necks, but most did not cut it quite that close, and sized the necks. I had less than .001 clearance all the way around, and I (partially) sized necks. We sized minimally for light neck tension.

They sized the neck by less than .003". I found that was the threshold got runout. The brass would spin within .001" TIR until I exceeded that magical .003" size. I wasted so much money back then. Those bushings were, are, expensive!

The other issue no one mentions is the theory of bullet movement: does the case expand away from the bullet first or does the bullet move out of the neck first. If the former, then runout does not matter. If the latter, then runout is critical. If both occurr simultaneously, which one is faster? Because an expanding case will alter the perfect bullet alignment we just spent all this time on.

 

[Walkalong]

They sized the neck by less than .003"

Way less.

Because an expanding case will alter the perfect bullet alignment we just spent all this time on.

Thus tight necked chambers.

 

[murf]

one can always minimize runout by modifying your reloading habits.

seating off the lands does not guarantee greater precision. and, in fact, may not be possible due to: long throats, magazine well restrictions, cannelure crimps, col restrictions (lever-action rifles), etc.

some bullet manufacturers even recommend seating well off the lands for best bullet accuracy (precision).

so, i agree whole heartedly with mr. scovill.

murf