Cure for poor neck runout on 280 Ackley Brass

[GaCop]

I ordered Nosler brass and Lee dies for the 280 Ackley barrel I got from Sinarms. Neck runout on new unfired brass was running .001. Fire formed brass is running .002 to .003. Full length sized in the Lee die and the neck runout increased to between .004 to .009. In hopes of solving the problem, I ordered the Lee 280 Rem collet die set which arrived yesterday. I ran approximately 8 cases through the collet die that had read .007 after full length sizing. There was no change in the runout after collet sizing? Now I'm at a loss as to what to do next to solve this problem. Accuracy with the full length sized brass had gone south when I shot some 168 SMK and 162 gr A-Max loads last weekend, hence my check of runout and discovery. Do I order a better set of full length dies, ie, Redding or Forester?

[dcloco]

Do you have similar runout with other brass on your press? (other calibers)

Loosen the locknut on the decapping pin/sizing ball and let it float.

Are you turning necks? What is the measured neck thickness of the brass?

What is the outside diameter of the neck on a piece of new brass? Fired brass NOT resized? FL sized brass? Neck sized brass? Loaded round?

[outlawkyote]

OK. Before putting a bullet into the case,(after FL sizeing) check your runnout on the neck. If you have runnout at this stage, its your full length sizing dies. If the runnout apears after a bullet is seated into the case, you need a new bullet seating die or possably do a better job camfering you case mouths. Try doing a better camfer job and measure runnout again. If no change, get a compatition seating die.
Check the brass coming out of the chamber (fireformed) for runnout in the neck. If you have runnout at this stage, get a new barrel.

[sharpshooter]

The problem lies in the brass. One side is stiffer than the other, maybe thicker or just harder ,but it will always move toward that side.

[GaCop]

The Nosler brass is only showing .001 straight from the box. Fired in the rifle, between .001 and a few at .002. Full length sized in the Lee die, and that's when the runout goes south, .005 to .008. Bullet runout is/was equally bad so the Lee die set will be replaced. Lee dies can't be set to only partially size, it F/L or nothing.

I've got Redding comp dies on order and as soon as I can afford it, I'll be ordering the Sinclair 4000 neck turning kit along with appropriate mandrels for the bench calibers I load for.

[outlawkyote]

Looks like you found the problem.

[dcloco]

Have you measured the other items?

The Lee dies may not be the problem.

[Jamie]

The Nosler brass is only showing .001 straight from the box. Fired in the rifle, between .001 and a few at .002. Full length sized in the Lee die, and that's when the runout goes south, .005 to .008. Bullet runout is/was equally bad so the Lee die set will be replaced. Lee dies can't be set to only partially size, it F/L or nothing.

I've got Redding comp dies on order and as soon as I can afford it, I'll be ordering the Sinclair 4000 neck turning kit along with appropriate mandrels for the bench calibers I load for.


OK, slow down a minute. As stated above, brass usually has a weak side and strong side. When you run your brass into a full length that has a pull through expander ball it is going to cause the weak side of the brass to stretch and give you run out problems. Running that same brass into a collet die will NOT fix it. Skip the full length step and go straight to the collet and then see if your run out increases. If it does then you need to look at the dies or the press. Yes, presses can cause errors. I started having runout problems and finally traced t back to my turret press flexing just enough to pull the die out of alignment with the ram causing the die to put uneven pressure on the brass.

[GaCop]

My Rockchucker Junior is more than 30 years old but still seems to loads accurate ammo. I Load my 308, 260 and 223 rounds on it giving me sub 1/2" at 100 yards and the 260 holds just over a half inch at 200 with 120 Ballistic Tips. My 308 loads with 190 gr SMK's group sub 1/2" at 100 yards and consistently drops the steel ram at 770 yards.

I rechecked the runout on the new unfired Nosler brass and it measured a consistent .001" for 10 cases.

[Jamie]

Have you necked sized any with out the full length die first? Have you checked the run out on your other rounds using that press? I shot plenty of 1/2" groups with my old turret press even when the run out was up around .010". While 1/2" is good, run out is what keeps them from being in the .3s. It's the reason for that flier you know you didn't pull. Take a couple pieces of brass and check runout, then run them through the collet die only and check runout again. All of my Lee collet dies produce as accurate rounds as my Forster dies.

I'm not saying the press is the problem, just saying you can't automatically assume it is not. My turret press was bought new back in the 60's.

[outlawkyote]

Get the redding dies, that will fix it, I'd bet a bag of donuts on it.
Im not a big fan of collet dies to beging with. After spending hours turning necks and then use collet dies to crinkle the necks back up seems redundant. Bushing dies will smoothly reduce the neck diameter without chewing up the necks.
Ive made an observation that my necks split sooner if Im using collet dies regularly.

Get the compatition Redding die set and you'll be very happy. If you want extream precision, get the redding compatition die set in 280rem and then use your chamber reamer to ream out the dies for even better concentricity.

[GaCop]

I'll try some of my unfired brass in the collet die to see if runout increases. I have noticed the case neck dragging on the collet dies mandrel rod when I run the case up into the die like it's not centered. I assumed this was because the runout on the F/L sized brass was so bad.

[outlawkyote]

With an AI cartridge, you shjould have no reason to FL size your brass. Reguardless, you'll be much more happy with the redding dies

[GaCop]

After sizing in the collet die, brass that has been loaded four times now is tight when I close the bolt so I figured bumping the shoulder would take care of this.

Tested some loads with the 162 grain A-Max pushed by IMR-4350. I used brass showing the lowest neck runout of .001 to .003. Groups in the .600 range so potential is there for accuracy. This barrel definately shows what loads it has a preference for, if it doesn't like em, groups open up to well over an inch. 100 rounds down the tube now and copper fouling is minimal.

[dcloco]

Stretch your target distance to 200 or 300 yards on your next testing session. Preferably 300 yards.

[Jamie]

I used brass showing the lowest neck runout of .001 to .003.


Were these ran through the collet die only? Those are not bad numbers.

[GaCop]

The local range I use (police range) is a max of 100 yards. I can shoot farther on my friends 1000 yard range but that's a 2 hour drive so is reserved for weekend trips. The brass full length sized in the Lee die was refired in the rifle. Neck concentricity now measures back to .001-.002 so the culprit was definately the Lee die. Sizing with only the collet die gives a runout of .001-.002. My Redding F/L die arrived yesterday. I ran a few cases through it and checked neck runout, averages was between .001 to .002 so I'm good to go. Sized brass chembers a bit hard but thats because of the tight headspace so I guess I can live with it.

[Jamie]

Neck concentricity now measures back to .001-.002 so the culprit was definately the Lee die. Sizing with only the collet die gives a runout of .001-.002. My Redding F/L die arrived yesterday. I ran a few cases through it and checked neck runout, averages was between .001 to .002 so I'm good to go.

I figured it was the full length die. Good to see that the collet dies are still living up to their reputation for accurate loaded rounds.