Uniformity in shoulder setback

[stubbicatt]

All. I understand intuitively that there are many variables in a lot of bottleneck brass which could account for the tolerances I have experienced in shoulder setback. If one piece of brass is a little harder than another, or perhaps the operator has a little more lube on one case than on another, this could account for different shoulder setbacks. The measuring tools too could have some tolerances built into them I suppose.

My question is, assuming one does not fiddle with the FL bushing sizing die (without expander ball) after initial setup, and his initial setup bumps the shoulder back on his bottleneck cases to some degree, what sort of variance in setback are you guys getting as measured with a comparator tool on your calipers?

It would be nice to have a number, say +/- .002 or something as an acceptable standard so that I don't drive myself nuts chasing an illusive and illusory "perfect" number.

Is there a technique for applying lube that assures it doesn't adhere to the shoulders of the brass, or the shoulder of the die itself to introduce variance?

Too do you have to reset your die each time you size your brass to accommodate its hardness in order to achieve the same .001" or .002" shoulder setback from "as fired?"

Probably I should just let this go, but thanks in advance for sharing your experiences.

 

[jelrod1]

In my experience you just have to eliminate all the variables you can. Most can, but I have not been able to get the best results using imperial sizing wax. For me the best has been a lube pad with RCBS lube. Put 10 pcs on it and roll back and forth. Gets a good even coat.

Annealing every time does help. I've experimented some with every time and every other time. When done every time it works best for me.

One other thing is that I pause at the end of the stroke a second or two. Seems to help mine repeat. I get weird readings if I go too fast.

 

[rg1]

Totally unscientific but I also feel the key to keeping zero-.001" shoulder setback is consistent lube. I use Dillion or Cabelas spray lube on a RCBS lube pad. A couple squirts on the pad and roll all cases to apply lube. The important thing using a lube pad is to keep the pad uniformly lubed. When the lube starts to get dry and sticky apply a couple more squirts to the pad. Also, like mentioned, a consistent pressure at the end of every stroke helps. I can load multiple year brass and keep less than .002" difference but on different brand cases fired in multiple rifles a die adjustment may be needed.

 

[stubbicatt]

So, "dwell time" is another variable? Keep the ram at the top of its stroke for a count of 2 or something like this helps?

 

[jelrod1]

Just throwing out ideas to try. Dwell time is often used in metal forming machines at the end of stroke to give the metal time to completely conform to shape. How much it helps brass in a reloading die I don't know, but there are situations where it does. Just from my experience if I size 10 cases really fast then size 10 pausing a second or two, the ones that were paused will measure correctly and some of the others will measure like they weren't pushed back enough.

Other variables are things like how well the die matches your chamber. There's just no one size fits all thing with reloading the way I see it. If your dies are sizing more or less on the body diameter than mine are we may get different results. Won't hurt to try several methods and see what works best for you.

 

[Shynloco]

All. I understand intuitively that there are many variables in a lot of bottleneck brass which could account for the tolerances I have experienced in shoulder setback. If one piece of brass is a little harder than another, or perhaps the operator has a little more lube on one case than on another, this could account for different shoulder setbacks. The measuring tools too could have some tolerances built into them I suppose.

My question is, assuming one does not fiddle with the FL bushing sizing die (without expander ball) after initial setup, and his initial setup bumps the shoulder back on his bottleneck cases to some degree, what sort of variance in setback are you guys getting as measured with a comparator tool on your calipers?

It would be nice to have a number, say +/- .002 or something as an acceptable standard so that I don't drive myself nuts chasing an illusive and illusory "perfect" number.

Is there a technique for applying lube that assures it doesn't adhere to the shoulders of the brass, or the shoulder of the die itself to introduce variance?

Too do you have to reset your die each time you size your brass to accommodate its hardness in order to achieve the same .001" or .002" shoulder setback from "as fired?"

Probably I should just let this go, but thanks in advance for sharing your experiences.

I have shared your pain in the past with similar issues. Got tired of various methods of determining the setback and went to using an RCBS Precision Mic for each casings of the calibers I shoot and reload for. And "YES" I do reset my FL die whenever the measurement on the Precision Mic calls for it. Probably a bit ANAL, but it works for me. BTW, I have also found that depending on the hardness of a casing and even the amount of lube you use, that can also account for a difference in the "bump" of the shoulder and even the number of strokes of the press handle you use to get the brass to comply with the bump you are seeking. Works for me. Also, my guess is annealing will also help alleviate that inconsistent hardness issue.

Alex

 

[Shynloco]

So, "dwell time" is another variable? Keep the ram at the top of its stroke for a count of 2 or something like this helps?

That too!

 

[stubbicatt]

So what range of measurements do you consider "good?" I mean, I shoot for setback of .001 to .002", but what I get? Yeesh. Sometimes none, sometimes .004"

 

[rox]

The measuring tools too could have some tolerances built into them I suppose.

My shoulder setback became much more consistent when I switched from measuring with a comparator to a case mic. I was never able to measure very repeatably with calipers and a shoulder comparator. It's easy to find how much variation there is in your measurements – just measure a few pieces of brass 10 times each and look at the variation. If you want to quantify it then work out the ES and SD. Make sure your measuring doesn't affect the brass though – it doesn't take that much force to slightly deform it. With a case mic I find the *measurement* to be one of the most repeatable of all case measurements. Typically well within 0.0005”.

So what range of measurements do you consider "good?"

In terms of the resulting shoulder position itself, if all the cases start from a similar point I expect no worse than +/- 0.001".

 

[jelrod1]

I use the Innovative Tech Gage and since this picture have switched to a different indicator I brought home from the shop. Like others mentioned a caliper is not the proper tool to be measuring to the .001. That is work for an indicator or Micrometer type gage. You can for sure tell differences with a caliper but the amount will be somewhat unknown.

 

[22BRGUY]

Great post stubbie; I made my own pad by simply tacking a thick shop rag to a short piece of 2x4. I like Lee case lube and simply squeeze a dab on my finger and smear it into the pad. Then I roll the case onto the pad making sure there is only a film on the walls of the case. I do not apply any lube to the shoulder area and do agree that the "dwell time" helps consistency. I do not have the body/FL die screwed tight down in the press but have small marks on the die set ring and then on the top of the press that I make with a felt tip marker. I hold onto the die with my fingers during the sizing process so it stays lined up with my marks. That way if a piece of brass comes out a little short of .002, I can adjust a little to add a thou. If it comes out with bump more that .002, I simply mark it and use it as a sighter this cycle. I use a Stony Point Head N Shoulders set to measure set back. Hope this helps...Best Wishes

 

[artbosco]

Purchase one of these gauges. Let a spring and gravity provide consistent pressure vice your own applied pressure which will vary. + or - .0005" is acceptable. Shoot for .001" push back.