Just finished reading JB's article in the August Handloader on reloading dies. I have a 308 that is typically 1 1/2-2MOA and never seems to do any better. Haven't messed with it in a while but decided to start looking at my loads since the rifle has been tweaked every way I can think of.
Put a few loaded rounds on the RCBS Casemaster and they were running out .006-.008 Hmmm... Checked a few fired cases and they ran out .001-.002. Took the stem out of my RCBS neck sizer and sized a few cases and they ran out .006-.008 Huh??? Switched shell holders and tried a different press all with the same results. Can't believe a neck sizer can induce that much run out.
Ran a few through a Lyman collet die and they were .001-.002.
Guess this one is going back to RCBS and probably ask them to replace it with a full length die since the Lyman is now my go to neck die.

Curious to see how this ends up. If the loaded rounds come out straight and if so, how the rifle shoots with the "new" straight ammo.

Keep us posted.

Same thing happened to me. Just change the name to Redding. Lee collet die changed things for the better in a hurry.

I went through this issue with my .308 Palma rifle recently setting up a FL bushing die. You don't state what brass is involved, but most .308s have very generous chamber neck diameters on the order of 0.344 inches. Your die is likely made to work with thin necked Winchester brass and is sizing down to 0.331 O.D. or less with the stem removed. That drastic downsizing in one step can easily create the runout you are seeing. As an experiment, try backing off the collet die a little, so that the RCBS neck die is only doing the final .003 amount of sizing. You may find the runout has disappeared. Even with my Lapua brass that I size to 0.336, I find that I have to size down in two steps to keep the runout low.

As an experiment I did shoot a 100 yard bench group with ammo having .004 to .006 runout that measured .63 inches at 100 for 5 shots with match iron sights. I prefer straight ammo though...

1. Conventional neck sizers are bad for runout more often than not.

2. I'm pretty sure you meant Lee collet die.

Preach on Brother!

I load for a bunch of different 308's and that's why my Redding bushing die for 308 is mostly in retirement.

What mathman said.

Conventional neck-sizing dies often result in misaligned case necks due to one of the reasons mentioned in the article: They don't provide any support of the case body during sizing. The result is often misaligned necks, whether using the expander ball or not.

If you're going to use a conventional sizing die to neck-size, it's usually far better to use a full-length die backed out a little. They usually provide at least a little support for the case body, preventing the case from tilting as much when the neck's pulled back over the expander ball.

Get a TruAngle tool for straightening rounds. Works great. I use a Sinclair concentricity tool, correct with the TruTool. Takes some practice, but works well.

Agree that the Lee Collet neck sizer is about the cheapest way to load concentric ammo. Of course, you'll need a body die to set back the shoulder when the bolt gets hard to close. You can use a next size up FL die, i.e. .308 FL as a 7-08 body die, etc.

Or, you can grind out the neck on a FL die such that the case neck doesn't contact the die. If you get a Deluxe Lee die set, it'll have the collet neck sizer and a FL sizer. I'm not a fan of their FL dies, making one into a body die is its highest and best use, IMO. Cheaper than buying a Redding body die and it works about as well.

DF

Shipped it off to RCBS yesterday. Asked that it be replaced with a FL die.
When I got the Casemaster after reading Gun Gack, I checked reloads of several calibers (some necksized although I usually PFL size) and wondered what the big deal was. Everything was .002-.003 max run out, most were less. Couldn't believe how far out the 308's were. Every single case was .007, nothing less, nothing more.
Lee (not Lyman, good catch MM) collet die seems to be the answer.

I'm glad that my properly adjusted RCBS fl die set produces run-out of .003" and less TIR. No need to fu ck around with all the bs you guys do...

Well thanks for telling everyone how you properly set your dies to get less runout..

Me I start with a universal decapping die, then I take my sizing die run the stem all the way up until stops, then turn it one full turn down. Then resize my cases. This has eliminated run out for me. Mule deer talks about this occasionally and it’s covered in one of his books.

Yeah but with the neck sizer I had it produced .007 run out with the stem removed. That's why I went to the collet die.

With that, that what bsa was trying to say/relay. A properly set up fl sizing die will eliminate run out for the most part. No need for a neck sizer or collet die.

Properly setting things up is important, but it doesn't have magical powers. I can easily demonstrate with a FL die that sizes great and straight with one make of brass, but not so well with another. This is because of different thicknesses, both sets of brass having very uniform necks.

I wonder if it was a 1970s era die? See the best die thread for JBs explanation.

I forget which gun writer suggested it long ago. If you loosen the decapping stem about a half a turn you will load way more concentric ammo. A friend had a 7x57 ackley that the decapping stem was so crooked a resized case wouldn’t chamber.

Fred

I should check my 7x57 die. This gets me thinking for sure.

With very good quality, concentric brass, maybe...

To me the neck collet system is less neck thickness sensitive. You get optimal ammo without neck turning, etc.

BR shooters weigh cases, sort accordingly, check neck thickness, turn necks, etc...

I'm a hunter, not a BR shooter. I want the best ammo I can load without all that prep work. For me the neck collet/body die system seems to perform best in that setting.

DF

Hence my request to replace it with a FL die. Like I said in a previous post, When I bought the Casemaster I couldn't figure out what the big deal was because I PFL size every other caliber except the 308 and all other calibers were straight.. One of MD's articles got me thinking about the 308 (a Kimber) because it has never done as well as it should even after all of the SAS tweaks and more. When I checked my 308 ammo I couldn't believe the run out even with the decap stem removed.
BTW you don't have to leave the decap stem lose to make straight ammo. If you run a case all the way in until the decap pin is in the flash hole then tighten up the lock screw it will be straight.

Got the replacement full length die from RCBS today. Ran a few cases through it and they have total indicator reading of .002 or less.
I'll get out and shoot a few tomorrow. It should be down to 103.














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Shot the new straighter loads this morning. The more concentric loads made a slight difference but not very noticeable. Haven't shot enough to quantify the difference. Too hot.

Having a bad die is pretty rare but I have had a few. Two of the bad sets were made by companies that are not in business any more. Another one of them was an RCBS 222 Remington set made in the 60's that I bought at a gunshow for $10. I have no idea if they had been modified but they loaded crooked ammo. The new replacements worker fine!