Neck turning tool & Advice please

[Gene]

[QUOTETo throw in an extreme example, my 6.5wssm has -no more than- .0005" clearance anywhere, right from the git go. So my brass with over 20 reloads still measures exactly the same as first fireformed to. I did not even touch the brass with a die until it's 8th reload!
[/QUOTE]

IMO, .0005 per side clearance on a loaded round is much too close. This will create varying pressures and thus poor accuracy. Clearance of .001 each side works fine.

The K&M neck tulrning tools are also very good. I buy one and dedicate it to that rifle, and never change the setting.

 

[Bart B]

There are folks who get excellent accuracy from SAAMI spec chambers for 30 caliber cartridges with .344" chamber neck diameters and .335" average diameter loaded round neck diameter on cases with .001" spread in neck wall thickness. Even with powder charges thrown from a measure with 1/3 grain spread, up to .003" bullet runout with new, unfired cases loaded on two Dillon 1050 progressives, they've produced sub 1/2 MOA 20-shot test groups at 600 yards and no worse than 2/3 MOA in a couple dozen different rifles. With weighed charges in new belted magnum 30 caliber cases, sub 7/10ths MOA 30-shot groups at 1000 yards. The best semiauto 30 caliber military rifles would shoot all day long inside 2/3 MOA at 600 yards with a good lot of mass produced match ammo (none of them shot that well with reloads).

IMHO, tight chamber necks and very uniform case neck walls aren't all that important. If these were critical for accuracy that good, the rifles and ammo having the above track record would not have done that well. I'm not referring to those occasional (rare?) few shot groups that set records and win benchrest matches. Those micro clusters are rarely, if ever, repeated by the same rifle-ammo combination, so they're not what the accuracy is one can count on all the time. The vast majority of groups a rifle shoots are much larger than their smallest ones, but most folks talk only about the smallest ones their hardware produces. I'm not impressed by those tiny, few-shot groups that set the records; they're more luck than reality.

Forster case trimming tools work great. With the piloted cutter chucked in a drill press and the base bolted/clamped below it, one can trim a bunch of cases pretty fast and uniform. Deburring the outside of the case mouth with a traditional tool is easy and reasonably fast. But I don't like the case mouth end of those tools; they leave a too rough and too sharp an angle at the inside of the case mouth that often scrapes off bullet jacket material unbalancing the bullet. You may need to use a magnifying glass to see the copper jacket material scraped off a seated bullet. I prefer and Easy-Out screw extractor of the size that a case mouth just fits about half way up its spiraled flutes. Turning it clockwise peens and smooths the edge of the trimmed case mouth at a better angle then using a bore brush chucked in a drill press cleans and smooths up that edge even better. Bullets seated in such case necks don't get jacket material scraped off.

 

[Mikecr]

Well, outside of that we experiment and try different case prep processes to try and find the factor(s) that makes the most difference. It's not exact, and that leads to comments like the above. The bottom line, think through and consider ALL factors that influence the burn sequence, consider that steel DOES deform and move about, then spring back. Then prioritize and select those factors that you think will make the most difference to your shot-to-shot consistency.

Jay, capacity checks are merely for matching brass,, and calibrating QuickLoad for initial CASE capacity. There is never any effort here(during case culling) to predict dynamic volume of a system.
The only occasion I can think of relative to your considerations, is while filling out a reamer print.

 

[Jay Kyle]

Jay, capacity checks are merely for matching brass,, and calibrating QuickLoad for initial CASE capacity. There is never any effort here(during case culling) to predict dynamic volume of a system.
The only occasion I can think of relative to your considerations, is while filling out a reamer print.

Mike,
I hear you.. my comments were more to the point of how it can sometimes be fruitless to take a hard stand on some aspects of reloading.

Jay

 

[Boss Hoss]

[QUOTETo throw in an extreme example, my 6.5wssm has -no more than- .0005" clearance anywhere, right from the git go. So my brass with over 20 reloads still measures exactly the same as first fireformed to. I did not even touch the brass with a die until it's 8th reload!

IMO, .0005 per side clearance on a loaded round is much too close. This will create varying pressures and thus poor accuracy. Clearance of .001 each side works fine.

The K&M neck tulrning tools are also very good. I buy one and dedicate it to that rifle, and never change the setting.[/QUOTE]


Gene---necks are getting too hard--need to anneal because the spring back will be greatly diminished. Bad juju for accuracy.

I use the Pumpkin Head Turners with carbide mandrels.

 

[TracySes23]

Variations in head stamp character size, quantity and depth will vary too. Neither does the variations in primer flame size and duration which cause more accuracy problems than a 1% spread in case weight or volumn.

All this aside, it's interesting to me that some folks do everything in the benchrest book to the nth degree to shoot their bullets as accurate as they can. Then others do a few simple things and shoot ammo testing groups smaller than and more often than benchrest records. There are reasons this happens.

You're sure right about that Bart. Some of us don't seem to shoot worth a crap no matter what we're pulling the trigger on.

Spencer

 

[Mikecr]

IMO, .0005 per side clearance on a loaded round is much too close. This will create varying pressures and thus poor accuracy. Clearance of .001 each side works fine.

Gene I put this chamber together as an experiment to find out what kind of clearance is REALLY needed, and what kind of sizing is REALLY needed.
You're right that .001" is fine, and I know now that half that is fine.