223 sizing variance?

[kyotekiller25]

Trying to get a consistent .002" bump on my lapua 223 cases and getting a .003" variance from low to high. 2 or 3 firings on them, they have not been annealed. Decapped seperately, RCBS case lube rolled on a lube pad, Redding FL bushing sizer with no expander ball and .248" bushing. Giving them 5-6 seconds each for dwell time at the top of the stroke. RCBS rock chucker. Mitutoyo digital calipers with hornady case gauge. Fired cases are coming out at 1.457"-1.4575" so my target goal was 1.455" Out of 50 cases, 37 are between 1.455"-1.456" and 13 are between 1.453"-1.4545" Is this acceptable? I feel like I'm chasing my tail here...Is it my sizing process, equipment, or all the cases haven't fully formed yet, or a combination of all 3? Getting pretty annoyed at this point, and my OCD of having everything exactly the same is not helping any...

 

[L.Sherm]

Are they mixed up by how many times there fired? If they are that could very well be your problem.
I dont anneal my Lapua and ADG brass but and get very consistent bump but I keep them segregated by times fired.

 

[SeabeeKen]

I had a similar issues last year. It took 5 firings to get the brass to fully form to the chamber. Once it did, bump was consistent.
Measure the bump BEFORE sizing and see if you get the same variations

 

[Hoser]

More than acceptable.

Differences in how much lube you use and how long it stays in the die and on and on. Dont sweat it. Go shoot.

 

[NF1E]

Not to do with the bump, but I find a .245 bushing and then a mandrel works very well with Lapua .223 match brass in my .223 match chambers to keep things on an even keel. Does sound like you may need more firings to even things out. I also switched from RCBS lube on a pad to Imperial applied with fingers which worked much better for my application. Whatta Hobby!

 

[SKWERLZ]

Not a terrible range,
Annealing will help as will some dwell in the press.

 

[Steel Mover]

In my procss for my match brass I use a CH trimmer that has a chamber style holder. I take new brass and turn it around, then square the base to brite across the surface, uniform the primer pockets, ream the flash holes, outside neck turn only to uniform the neck thickness, then trim using an RCBS Trim Pro with a 3 way cutter. Use an RCBS bench priming tool, set the bullets .003 off the lands using a bullet eating tool and a threaded, fired case. Then I fire form with a full load, so the cases fully form on the first shot. Then seperate the cases by the actual water capacity f each case. Mark the base with a carbide dental burr. From then on the cases are neck sized only. The rifle is trued, squared and the bolt face is squared. So you are shooting square to square and concentric.
If the same precision is applied to the rifle build, the result is accuracy. Once the brass is prepped, it is done, except for the normal trimming and cleaning.
Prepping your brass is very important if you want consistant performance. For match or best precision shooting, you really should also check your bullets for odd shapes or weights.

 

[Kracken McGraw]

Using Redding competition shell holders to get your bump and having them setup with some camover in your rock chucker press might be your key to consistency.

 

[dellet]

Before getting all worked up in your sizing process, make sure your measuring process is rock solid.

Your .003” variance is better looked at as +/- .0015”. That’s actually pretty good using a caliper and Hornady tool. Never mind you’ve sorted into groups of .005”.

If you want an exercise in OCD torture, count what you have in each group, mix them all up again and remeasure. Keep doing that until you have the exact same number in each group twice. No extra groups allowed.

If we don’t hear from in a couple days, who do we contact for a welfare check?

 

[243winxb]

Fired cases are coming out at 1.457"-1.4575" so my target goal was 1.455" Out of 50 cases, 37 are between 1.455"-1.456" and 13 are between 1.453"-1.4545" Is this acceptable?

A Redding Reloading Competition Shell Holder Set # 10 is needed to remove slop from the press linkage. Die & Shell holder must make contact.
Even this method may have a variance, with a RCBS cam over press.

*Acceptable? I think yes.* My Savage Axis allows the firing pin strike to set the shoulder back .006" Dead primer test.

A Remington 700 extractor may not allow this much change in head to datum?

After firing, all brass should spring back some. Spring back is needed, so fired shells can be extracted/ejected.

 

[Kracken McGraw]

I agree with losing the lube pad and doing them by hand with Imperial or Hornady sizing wax.

 

[K22]

In my experience, many issues can influence sizing consistency. Here are some I've noticed. Before I get into that, what is your shooting discipline? If it's hunting, even precision varmint/predator hunting, I doubt that amount of variation will show up on target.

1. Singe brand / lot of cases and rotating their use so each case receives the same amount of firing and sizing's.

2. Operator technique and skill in obtaining consistent measurements. Check your repeatability.

3. Inconsistency due to bump gauges the employ inserts for multiple caliper groups. I prefer a Whidden bump gauge since it is single piece with no inserts. If you are using a gauge that employs inserts and are changing them out, place match marks on the holder and inserts to assure consistent position each time re-assembled.

4. Lube and sizing operation uniformity. I prefer Imperial sizing wax. It gives me the most consistent sizing "feel". A slight pause at the top stroke the press can help.

5. Accumulation of lube in the F/L die, especially in the neck area. I dry brush mine out after each sizing session with a nylon bottle brush.

 

[NF1E]

Just finished up prepping a couple 200 rnd batches of .223 and then .308. I start by annealing then de-priming/sizing with FL bushing dies, then into the wet tumbler with ss pins, lemi shine and dawn for an hour, then into the dryer for a couple of hours. These should be ready for trimming, then setting neck tension and loading shortly after noon. Whatta Hobby!

 

[jelenko]

Just to add to what dellet said.

When you measure the bump, try rotating the case 90* and take another measurement, then rotate another 90* and another measurement.
Using a Forester sizing die in a COAX press I've found .0005 to .001 differences.

You can also try not rotating the case and just take a couple measurements. It's easy to have the measurements different by at least .0005.

When I was chasing consistency in resizing, I found there was a sweet spot in the amount of lube. The best consistency I ever got on a lot of cases was +/- .001.

 

[kyotekiller25]

Thanks for all the quick reply guys.

Just to answer some follow up questions. The brass has all been fired the same amount of times, it's either been 2x or 3x. Sometimes I just forget if I mark them when they're all fired, or when I size them. I need to start writing the date so I don't either forget a firing, or double up. The last year has just been very very stressful with work and life in general. The variance is still there before sizing. I do rotate the case 3 or 4 times when measuring. I have measured each case at least 5x before and after sizing, and I've become very consistent in my measurements. Out of those 50, maybe 3 or 4 had a .005" difference from what I came up with the prior 5 times. I did notice when the cases are in the die sizing at the top of the stroke, there is a very very slight gap, so I don't believe I'm getting any cam over, I will provide a picture here of that. On a side note, the rifle shoots amazing. 10 shot groups at 100 do .6"-.7" and it will hold 3/8-1/2 MOA out to 800 and around 1 MOA at 1K. It's just the OCD in me hates when things aren't exact. Then again, I probably need to have more realistic expectations with my equipment and myself.

 

[358WCF]

The variance is still there before sizing.

Do any of them chamber hard yet? If not they aren't fully expanded & you're pissing into the wind.

 

[kyotekiller25]

Do any of them chamber hard yet? If not they aren't fully expanded & you're pissing into the wind.

No sir, none of them chamber hard at all.

 

[Kracken McGraw]

Thanks for all the quick reply guys.

Just to answer some follow up questions. The brass has all been fired the same amount of times, it's either been 2x or 3x. Sometimes I just forget if I mark them when they're all fired, or when I size them. I need to start writing the date so I don't either forget a firing, or double up. The last year has just been very very stressful with work and life in general. The variance is still there before sizing. I do rotate the case 3 or 4 times when measuring. I have measured each case at least 5x before and after sizing, and I've become very consistent in my measurements. Out of those 50, maybe 3 or 4 had a .005" difference from what I came up with the prior 5 times. I did notice when the cases are in the die sizing at the top of the stroke, there is a very very slight gap, so I don't believe I'm getting any cam over, I will provide a picture here of that. On a side note, the rifle shoots amazing. 10 shot groups at 100 do .6"-.7" and it will hold 3/8-1/2 MOA out to 800 and around 1 MOA at 1K. It's just the OCD in me hates when things aren't exact. Then again, I probably need to have more realistic expectations with my equipment and myself.

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Not that it’s necessary but I think that Redding Competition shell holder set would be beneficial. You just set that +.10 shell holder in the set with cam over in your press then just simply change out to the lower number holder’s in the set till you get your desired.002 bump

 

[358WCF]

No sir, none of them chamber hard at all.

Do as you're comfortable with, but I usually back the FL die off about 1/2 turn (or more) from touching the shoulder until there are a few cases which chamber with a little feel. Using that snug brass to set the FL die just until the bolt closes easy, then half a BCH (a highly technical unit of measure) more . Write that dimension down in your records. Lock the ring & you're done for maybe the life of that lot of brass. After a bunch of firings, it may require another BCH of sizing if you load them warm. I dont anneal except when necks start cracking, so that may affect sizing if you do.

When measuring remember that when the lower case is sized, the base to datum length may grow because the squeezed inward brass has to go somewhere which will affect the measurement of base to datum between fired & partially sized cases.

 

[kyotekiller25]

Do as you're comfortable with, but I usually back the FL die off about 1/2 turn (or more) from touching the shoulder until there are a few cases which chamber with a little feel. Using that snug brass to set the FL die just until the bolt closes easy, then half a BCH (a highly technical unit of measure) more . Write that dimension down in your records. Lock the ring & you're done for maybe the life of that lot of brass. After a bunch of firings, it may require another BCH of sizing if you load them warm. I dont anneal except when necks start cracking, so that may affect sizing if you do.

When measuring remember that when the lower case is sized, the base to datum length may grow because the squeezed inward brass has to go somewhere which will affect the measurement of base to datum between fired & partially sized cases.

Thank you. What exactly does BCH stand for?