Sizer not sizing all brass the same??

[Winny94]

I'm running into an issue w/ my full length sizer. About 15% of the brass is not sized the same as the rest, and some is longer by up to .0015, and shorter by nearly the same. Most land within .0005. (This is a base to shoulder junction measure)
My setup is:
Coax press
Hornady one shot
Redding type bushing FL die w/ .289 bushing and expander & decapper removed
Norma brass
Brass comparator is the Sinclair insert type

Improper/inconsistent lube?
Fluctuating pressure on the ram?
What are some areas I could trouble shoot to resolve this issue?

 

[Ranger188]

Is all the brass starting out at the same length before sizing?
If it is, then take out the bushing and the expander(if its still in) try it again on a couple cases
maybe your FL sizer isn't bottoming out in the press.
Not trying to be a smart ass or anything, are you sure you
have a FL bushing sizer and not just a neck sizer?

 

[TheGerman]

It's either lube or the pieces aren't starting at the same length at the shoulder. This is pretty common; more firings and annealing start to get rid of this over time.

Measure the shoulder of 10 of them and see where it is. Then size the ones that are the same and see if they end up all the same length. If they do, the different shoulders in some pieces is your culprit.

Otherwise its lube or something inside your die is weird.

 

[Strykervet]

Is your die even accurate to that scale? .0001 is to the ten thousandth of an inch. We're usually measuring to the thousandth, .001. Something I learned in math, just because you can measure something to that degree doesn't mean the process you are measuring is accurate to that degree. What the tolerance is for that I have no idea, you'd have to call them and talk to an engineer.

A lot can cause a ten thousandth variation. Is the die locked down tight? Is there any play in any of the die parts? What about external parts like the shell holder? Did you clean the die and reassemble it to ensure there's no debris or foreign material? Lube can carry shit in there and leave it. Does the brass have a uniform layer of lube? What about the necks, is there more resistance with some vs. others when the expander comes through? Even the amount of force on the over-cam, is it always uniform? Some of this is hard to determine and you just need as uniform of a process as possible. And knowing the tolerances if you're gonna be measuring down to the .0001 or less, to know IF you can measure down to that, is nice.

I'd start with that. You can call the mfg. and ask them what the tolerance is with that particular die too. And kudos for using a micrometer I guess, I'd never have seen that. If it fits the Wilson gauge and it all looks uniform and random cases check out to the .001 I'm fine I suppose.

If you want something that works better than Hornady One Shot (according to a couple of users who did) I make a concentrated lanolin lube you can cut 100% (double it with another bottle of alcohol) and when heated it sprays and spreads with a real even coat and makes working the press easy. Probably the closest thing to Imperial wax that you can spray and certainly the strongest. An easy stroke means less wear on the dies and less work on the brass and can result in a more uniform process in general. Just spray in a bag and mix 'em around or do it in a plastic tub and work 'em around by hand. It's in the PX on here or you can PM me if interested. It won't necessarily be the answer to your prayers with this particular issue but it does help eliminate one variable and makes sizing super easy. You should be able to size with almost no resistance.

 

[spife7980]

I’ve noticed that too. However what I’ve also noticed is that they still size back the same amount. They mostly all measure 1.556 and bump back to 1.554. One piece could measure 1.555 to start but it will still get bumped back to 1.553, a piece that’s 1.557 will get pushed back to 1.555. I think (guess really) that the comparator and the brass hit in just different enough of a location to measure that change due to slight differences in the shoulder material thickness/hardness giving way or springing back.
Stick a long one and a short one in the chamber after sizing with the firing pin and ejector stripped. Will the bolt still fall easily on both of them? I bet so.

 

[918v]

Convert the press to shell holders and bottom out the die against them. Then your shoulder bump will be consistent.

 

[Sean the Nailer]

Maybe I'm not grasping the whole situation correctly, but the 'sizing' die is what squishes the brass back into its original intended shape. And it does so through compression, mostly. Now, the only venue for anything to 'squish' out to, is length.

So can you guarantee that the metallurgy of all the brass in question is equal? As has been suggested above by another, was all the brass the same EXACT (to the ten-thousandth of an inch) length to begin with?

The correct procedure for trimming brass is after it has been sized. Or, simply belay my last.

 

[TriggerHappy0125]

Nothing we are using in reloading is capable of holding tolerance exceeding +/- 0.001” if that. Exceeding those tolerance in reloading dies would be cost prohibitive. I have only seen those types ID tolerances on very specialized press fit tooling. To get tolerances of +0 -0.0005 or better requires ID grinding and it’s a very expensive and specialized process.

 

[palmettoman]

I sometimes get the same variations you're getting. Drives me crazy.

I was sizing some several times fired Starline 6.5 cases the other day and had a couple that would not size down to the others. They had all been shot from the same rifle, annealed, and lubed the same. It was comical. It got to the "I'll show you who's boss" level and I had to adjust the die to get their shoulders to move.. Weird, but I won.

 

[MilSpecOkie]

Get rid of the One Shot and use Unique or Imperial Sizing Wax and try again. You will likely see a big improvement. Been there, done that. Unique is all I use now.

 

[flyright]

I believe it's partly the metallurgy. There always seems to be a weird piece in every 40 or so cases that will over size but more often under size compared to the rest. I've set those pieces aside and used them for shooting just to see how they differed (not much) and some of them ultimately "normalized" but not many. The lanolin/alcohol mix did allow me to achieve my goal of +\- .001 or less difference much better than anything else, though.

 

[jd5521]

Are you setting your does up with a bit of cam over?

 

[McHaggis]

One thing I’ve noticed is that if you up stroke quickly, ie withdrawl the case out of the die too fast, it can stretch the case a little. As others have mentioned the correct lube helps. Do this part of the stroke slowly and smoothly until you feel the case “comes away” from the die.

 

[WinJim1863]

You said you were using a CoAx press, Forster I presume. As you know the Forster has sliding jaws instead of a shell holder. If you are using a spray lube and the alcohol hasn't totally flashed off you will get a little dribble into that jaw assembly. could that by hydraulically locking at times?? probably not but I would try taking the jaw assy apart and cleaning everything just to make sure.

 

[MilSpecOkie]

One Shot just isn’t that slippery. Once you try something like Unique, you will see how much smoother sizing goes.

Like I mentioned before and McHaggis said also. The cases get stretched back out sometimes with the OS lube. It’s the only way some cases are E.G. 1.535” long when measured and some longer at say 1.537” long.

Too much neck sizing and then dragging an expander ball back though could stretch the neck area up some. You can remove the expander to test those waters. Just don’t forget to expand the necks later or good luck seating bullets.

 

[jd5521]

Remove all your expanding balls and get a sets of mandrels. One more step in the process but worth it IMO.

 

[BLKWLFK9]

Mine does the same. Varies about .001-.0015. With that said, I'm still getting SDs of 3-8ish and consistent groups in the .2s. I'm not worried about it.

 

[Lucky Se7en]

I’ve had good luck getting more consistent measurements after FL sizing after I started rolling the cases with lube on a pad. I used to see it as an unnecessary step when I can just smother it with what I thought was a consistent film of lube other ways, but not anymore

 

[MilSpecOkie]

I’ve had good luck getting more consistent measurements after FL sizing after I started rolling the cases with lube on a pad. I used to see it as an unnecessary step when I can just smother it with what I thought was a consistent film of lube other ways, but not anymore

How do you get the shoulder and neck lubed with a pad. Needless to say, but I’ve never used a lube pad.

 

[spife7980]

How do you get the shoulder and neck lubed with a pad. Needless to say, but I’ve never used a lube pad.

Press them into the pad if the pad is squishy enough.
That said, usually the pad users are more old school where they say not to get lube on the shoulder or neck. But I say screw that gall inducing bs and I lube everything.

 

[XLR308]

Get a Redding FL bushing die and don't look back.

 

[jd5521]

Use this for neck and shoulders then lube pad for body and FL size.

 

[bax]

I use Lake City LR .308 cases. Year 06 has smaller flash holes than 11 and shoulder-bumps about one thousandth different - even when they come out of the gun about the same. I anneal before sizing, that really helps. I use plenty of Imperial - no dents but I use plenty. I let the brass sit in the compressed position (ram up) for the time it takes to smear Imperial on the next case, the longer dwell time helps. My shoulder lengths range across about 1.5 thousandths. Using the RCBS precision case gauge, the shortest case may be about zero and the longest about 1.5. The actual numbers depend on the gun the case came from and the gun for which I am making ammo. I use a Redding button die with a .333 button, this produces a case with .302 - .303 neck ID. I run them over a mandrel and that makes the neck ID .304. I would prefer a bit more neck tension but the gun says otherwise. When using the mandrel, I commonly use the Dry Neck Lube graphite kit shown in the picture above. If the necks are soft enough, I don't need it.

 

[Lucky Se7en]

What is the general consensus as far as what is good for a head space tolerance? Idk if I have yet to have a batch yet where I’ve measured every single one to be the same exact measurement to the thousandth of an inch. I’m usually pretty complacent if one of every several is .001” off. It could also be partially dependent on my ability to measure, but even my fire formed brass is never exactly the same