How much to neck turn Lapua brass?

[scott2314]

I got some new 220 Russian brass and fireformed it to 6ppc. I turned the necks down to 268 just so a seated round chambers. It does not allow the neck to expand at all, and all the neck die does is punch the primer out. The neck is still tight enough to hold a bullet. Should I turn the necks down more? Shoot them and see how the groups look? This is a factory Ruger that I inherited.

 

[CJ6]

Find out what the chamber neck (Cerro-safe cast it) is and get .002-.004 neck/chamber clearance on a loaded round.

 

[dkhunt14]

You need to know what neck is in the gun. Then allow for at least .002 or .003 clearance. I can't believe a factory gun has a tight neck. Although Ruger made a few PPC guns and the inventors got the first one. I seen it sold at a sale a few years ago. Maybe Ruger would know if the barrel was never changed. Matt

 

[scott2314]

You need to know what neck is in the gun. Then allow for at least .002 or .003 clearance. I can't believe a factory gun has a tight neck. Although Ruger made a few PPC guns and the inventors got the first one. I seen it sold at a sale a few years ago. Maybe Ruger would know if the barrel was never changed. Matt

Thanks for the info, I'll turn another 2 or 3 off. I shot a 22 bullet as the 1st step turning the brass to 6ppc. I then seated a 6mm bullet in the case and could not chamber it. I measured the case thickness at 015 where the brass I had was 011. I figured it would fit without turning. I know real benchrest shooters load at a match, so thought maybe one intent of the tight necks was so they don't resize.

 

[CJ6]

Most "factory" size dies WON'T size a neck on TURNED brass. Look into getting bushing style dies with bushings -.002. -.003 smaller in diameter than a loaded round

 

[/VH]

You need to know what neck is in the gun. Then allow for at least .002 or .003 clearance. I can't believe a factory gun has a tight neck. Although Ruger made a few PPC guns and the inventors got the first one. I seen it sold at a sale a few years ago. Maybe Ruger would know if the barrel was never changed. Matt

Matt,

At one time, didn't Sako and maybe Norma make some already formed PPC brass and possibly some loaded ammo? Maybe Ruger's intent with their neck diameter was for brass other than unturned and fire formed Lapua .220 Russian to be used.

 

[JRS]

SAKO produced the official SAAMI 6PPC round, and called it the 6PPC USA. The Ruger's were chambered for the factory SAKO offering. You can purchase 6PPC brass from Norma. Are you sizing the case after you fire form it to 6mm, or simply seating a bullet in the formed case?

 

[spclark]

Most "factory" size dies WON'T size a neck on TURNED brass.

Kinda true, but if you know what your chamber neck diameter is and your desired neck clearance, you might find a factory die works just fine after you turn necks to a thickness that suits the other parameters.

Otherwise most factory dies oversize necks as they expect you to bring them back to diameter with the included sizing button... which significantly shortens brass life AND can lead to off-center necks as well.

 

[LHSmith]

I got some new 220 Russian brass and fireformed it to 6ppc. I turned the necks down to 268 just so a seated round chambers. It does not allow the neck to expand at all, and all the neck die does is punch the primer out. The neck is still tight enough to hold a bullet. Should I turn the necks down more? Shoot them and see how the groups look? This is a factory Ruger that I inherited.

You must use a matching expander mandrel (to the neck turn mandrel) AFTER F.F. in order to properly turn necks. IMHO you may have a headspace (case shoulder to casehead) problem in which you need to bump the shoulder a bit.
The reason Benchresters neck turn brass is to control 1/the exact amount of radial neck clearance to the chamber neck and 2/ better control of neck tension.
FWIW the Nosler Reloading Manual #7 lists the loaded round neck dia. of 0.265". I measured some .220 Sako brass -it has a neck wall thickness of 0.0123" while .220 Lapua runs 0.015".

 

[Catfish]

I like .002 expansion. The less expansion the longer the case life and with .002 it will still fit with a little crud on the case.

 

[Hummer]

Necks with min dimensions will fire and spring back and become smaller. Just because a case doesn't need sizing to hold a bullet doesn't necessarily spell doom.

Did you experience any resistance closing the bolt on the first firing? Or hard openings after firing.

Dave Manson, (Manson Precision Reamers) told me he has benchrest shooter/customers that shoot necks that are as tight as .0005" larger than loaded rounds.


My custom reamers I have made on what I call the 222 principle which means nothing moves over .002 anywhere (neck expansion, shoulder movement forward or base expansion on firing.
On M118 Match ammo I had a reamer made with a .339 neck. M118 will just go in.

Humpy Gage:
I have a section of barrel about 1" long and ran the reamer into it until about 1/8"-1/4" below the shoulder was inside the section. I then reverse the section in the lathe and start cutting it off till I it is just forward of where the chamber stops. In that way I know exactly where the neck is in relation to the end of the neck on a fired case. With a 10X loop you can get a detailed view and no guess where the neck is.

Also before I run new ammo into that rifle I try every round I am about to fire in the Humpy Gage to make absolutely sure there is no interference fit.


About every 100 rounds of M118 I would have one that showed just a tad of interference which proved to be a very slight lip at the case mouth I could feel with thumbnail so I gave it a twist in emery cloth and took it right off.

Thus every round goes in, stops at shoulder and there is no perceptible movement.

You can take a Sharpie marker and blacken the necks of your reloaded rounds. In a safe place chamber the round, close bolt and open it. If you are too tight you should see where the chamber scraped off the marker ink.