Case-Sizing Addition: Apples, Oranges, and Bananas

The following is a specially-adapted excerpt from the forthcoming book, “Top-Grade Ammo,” by author Glen Zediker, owner of Zediker Publishing. Click here to order from Midsouth.

by Glen Zediker

First, I want to thank everyone who’s reading “Reloaders Corner,” and especially those who take the time to post comments and questions. That’s the fun of the web for me: it’s a closer connection to my readers and fellow shooters. Judging from a few responses to the last couple of articles on case sizing, I’d like to offer a little more detail to ensure there’s been no misunderstandings or misinterpretations.

Here’s a nice 1000-yard target from David Tubb, 11-time NRA National High Power Rifle Champion, 6-time NRA High Power Long Range Rifle Champion, two-time Wimbledon Cup winner, and current Long Range World Champion. This target was fired from prone using full-length-sized cases, with carefully constructed rounds. The rifle is a TUBB 2000 bolt-action chambered in the 6XC cartridge. Tubb sizes the case bases an additional 0.0005 smaller than SAAMI specs, and sets the case shoulders back 0.002 inches.
Here’s a nice 1000-yard target from David Tubb, 11-time NRA National High Power Rifle Champion, 6-time NRA High Power Long Range Rifle Champion, two-time Wimbledon Cup winner, and current Long Range World Champion. This target was fired from prone using full-length-sized cases, with carefully constructed rounds. The rifle is a TUBB 2000 bolt-action chambered in the 6XC cartridge. Tubb sizes the case bases an additional 0.0005 smaller than SAAMI specs, and sets the case shoulders back 0.002 inches.

I don’t have a lot of space here to cover all the smaller but often important peripherals associated with any larger topic. In the few hundred words I have available, it has to be a more specific treatment of a more specific thing, and that’s why I’ve been doing some of this material as series installments. There are a number of folks who claim neck-only sizing is necessary for best accuracy, and, in effect, that full-length sizing is a compromise, favoring function over accuracy. I want to use this space here this time to clarify a few potential confusions. And I’m not even really disagreeing with anyone.

To review, neck-only sizing is when only the case neck, all or some portion of it, is sized to adequately retain a bullet for another firing. The case body is not touched by the die interior, and the case shoulder may or may not be set back; that depends on the die design and operator preference. The idea is to better preserve the fired case dimensions; that is, make the case more closely mirror the rifle chamber’s dimensions. One advantage of neck-only sizing comes to those who expect dozens of loadings from a case. This tactic does, indeed, minimize case stretching on subsequent firings.

Mostly, do not get the impression that full-length sizing — essentially following the steps and methods I suggested in the past two articles — is short-circuiting on-target accuracy. It’s not. Not if tooling is what it should be and the operator makes the investments in money and time to gauge influential dimensions.

ejector and spring
One old accuracy trick is to reduce ejector pressure. That’s easily done in most rigs: just shorten the ejector spring, if you know what you’re doing. The author does that, or has it done, on all his rifles. The ideal amount is to have a stress-free contact of the spring against the ejector at installed height, such that the spring isn’t compressed until the ejector moves in as a round is chambered. That’s usually the minimum pressure needed to make it functional and doing its job 100%.

There are some who maintain that they only get good groups from neck-only sizing, and, moreover, that they get gatherings rather than groupings when they full-length resize, or when they use factory ammo. There can be some reasons for that, and they may have something to do with rifle-chamber dimensions.

A lot of factory-produced bolt-actions have fairly generous chambers; they are a little larger diameter and usually favor toward the longer end in headspace (but with all numbers within SAAMI tolerance). A rifle produced for across-the-counter sale needs to accept virtually any commercially available ammunition. If someone measures as many representatives of factory ammo as I have, it’s pretty clear that there are dimensional differences, significant differences. Additionally, it’s common to find some slightly oval chambers in factory guns. That has a lot to do with the freshness of the tooling when that barrel was reamed.

So, let’s construct a circumstance where we have a chamber that’s a tad amount big and a cartridge case that’s been manufactured on the smaller end of SAAMI blueprints. And this rifle has an ejector. As soon as the bolt closes, the ejector is bearing against the case, and it’s bearing well off-center.

For more clarity: rifles have extractors and ejectors. The extractor is the “claw” that rides in the case rim groove. It’s there to pull the case from the chamber. The ejector is a small, cylindrical piece that’s spring-loaded; its job is to lean or tilt the case toward the ejection-side of the action as the case is withdrawn from the chamber. It’s not commonly possible to encounter a bolt-action that doesn’t have an ejector (custom Benchrest actions and some Long Range Rifle specialty actions don’t).

Ejector Detail in Bolt and Ejector Case Leverage
Here’s an ejector and here’s what an ejector does. Pressure levered against the case will warp the case. It’s a small amount — all these things are small amounts. Case-body sizing helps straighten out the “banana,” that is, a curve in the case body, making it a smaller banana.

Back to the reason I said anything about ejectors in the first place. It makes a banana out of a case. This is unavoidable. The pressure steadily being put against the case base by the ejector warps the case under fire. It’s going to happen on each and every case fired. The bigger the dimensional differences, the greater the warp. Of course, as the uses and reuses add up, the nature of expansion changes. A case can warp one way, and then another way, and then another. Brass has a “memory,” by the way, and we’re always fighting that. Cases tend to follow the same expansion pattern regardless of orientation in the chamber.

There are some, and I’m among them, who think case-body sizing is a good thing to help allay the effects of warped cases, when they return to a correctly-dimensioned chamber. If a rifle chamber is on the larger side, then I honestly think that neck-only sizing may be doing a better job working around it, or working with it, and that’s the primary source of accuracy improvement. I also know that little bit there will get pounced upon.

The “70” on the dial indicator isn’t a measurement of anything; it just happened to be the position of the indicator. What matters is the area the indicator sweeps, measuring points about the circumference of the case. More needle movement means more warping. This pair of photos shows the amount of warp on a new case measured using a V-block-style concentricity fixture with a dial indicator. Even new, they’re not perfect.
The “70” on the dial indicator isn’t a measurement of anything; it just happened to be the position of the indicator. What matters is the area the indicator sweeps, measuring points about the circumference of the case. More needle movement means more warping. This pair of photos shows the amount of warp on a new case measured using a V-block-style concentricity fixture with a dial indicator. Even new, they’re not perfect.

I’m shooting custom-chambered custom-made barrels in my rifles. I do not request “tight” chambers (in any dimension), but they sure aren’t oversized. I like to have headspace set to closely accommodate the case brand I plan to use; doing that minimizes case stretch from the get-go.

Using a concentricity fixture that’s designed to allow isolation of points of measurement along the cartridge, it’s easy to see the warp. Spin a new case, spin a fired case. Some experiment with marking the “high” (or low) point and reinserting the round in the same orientation each time. That’s tedious but possible using a single-shot approach to firing. The point is, that after full-length sizing, I see less runout. I have also seen additional body sizing improve the accuracy of rounds destined for use in rifles with smallish chambers, and that’s one of the first steps many competitive Benchrest shooters take when they’re losing the gilt-edge on groups. For that, they use a die that doesn’t touch anything but the case body.

This pair of photos shows the amount of warp on a fired case measured using a V-block-style concentricity fixture with a dial indicator. As before, the “70” on the dial indicator is just the position of the indicator. What matters is the area the indicator sweeps, which shows they are a little less perfect than the new ones above.
This pair of photos shows the amount of warp on a fired case measured using a V-block-style concentricity fixture with a dial indicator. As before, the “70” on the dial indicator is just the position of the indicator. What matters is the area the indicator sweeps, which shows they are a little less perfect than the new ones above.

If a case becomes a banana, it should be a smaller banana rather than a bigger banana. More technically, it’s a question of if the chambered round can sit in the center of the rifle chamber.

When David Tubb designed the sizing die for his 6XC cartridge, he added an additional 0.0005 inches downsizing right at the case head area. He maintains that is a key to good accuracy at long distance. He’s also setting the case shoulders back 0.002 and running a little more “neck tension” than you might imagine (difference between sized case neck inside diameter and bullet diameter). Tubb maintains that the consistency of case expansion has been an overlooked element in accuracy. Believe me, he’s tried everything, including neck-only sizing, to improve scores at 1000 yards.

And this pair of photos shows the amount of case-diameter variation after they’ve been full-length sized — the variation amount is nearly back to where it started in the new cases.
And this pair of photos shows the amount of case-diameter variation after they’ve been full-length sized — the variation amount is nearly back to where it started in the new cases.

If you’re running a factory bolt-action rifle, by all means try neck-only sizing. If you want to compare results to full-length sizing, just make sure you’re doing that second operation correctly.

52 thoughts on “Case-Sizing Addition: Apples, Oranges, and Bananas”

    1. This was about the most long winded waste of time of yet this morning. Instead of taking up so much space and wasting time. Why can’t these articles just get to the point. I’m not even sure now what I just read. and I’m not going back and doing it again. I could sit here and thank my mom . my teachers and even my parole officer for being the great writer that I am today. But hey. Whatever dude.

      1. There’s always a little Go FXXK yourself in every “whatever dude” Why don’t you add something to the stream or just shutup great writer

  1. I’ve been reloading for 15 years now and it’s amazing how much info is out there that I still didn’t/don’t know. Long range varmint hunting and 300m F-Class compitition is what I have been doing. Admitedly, I’ve never invested in a truly custom rig with a quality barrel and action. My rifles are all off-the-shelf by Rem., Savage, Browning, T/C, etc. Some are bull-barreled for F-Class and extended varmint shooting like prairie dogs and they are fairly accurate. By that I mean 3/4 – 1 moa. I have two rifles (an AR-15 and a Remington SF-FV .204 Ruger) that are much better. The .204 shoots .3-.5moa with just about anything I shoot through it – either factory or my reloads EXCEPT MidSouth’s “Varmigeddon” bullets.
    With my F-Class reloads I’ve tried bullet depths from seated in the lands to .060″ from touching, matching case wts., matching bullets wts., and neck sizing. My results are not as straight forward as I’d hoped. I may try your approach in the future to see is my cases are banana’ing on me.
    Thanks for the tip.

  2. This is really good info and detailed enough to understand. I think this explains why some of my brass wobbles when I’m trimming.

    1. That is, no doubt, a factor. You might consider trying an LE Wilson trimmer. That’s the best of the “crank” trimmers, in my mind. It holds the case by its body, not by its ends.

  3. Glen.

    I enjoyed this excerpt. You have a gift for making the seemingly complex simple.



    1. Thanks for the kind words. Sometimes it takes a few words to get through a topic. Some folks just want a list, but my goal is to really help folks understand a lot of the things going on in cartridge loading.

    1. you will have to screw your die in the press lower to the shell holder give it say 1/25 turn until you get the shoulder bump back to your preference hope this helps.

    2. You’ll need a comparator. This is a tool that can measure the headspace dimension of a case fired in your rifle. That measurement is then used to set a resizing die to only set the shoulder of a sized case back .002-.003. It can be time consuming and the results can vary between different brands and the condition of brass. Lots of video on Youtube about this subject.

    3. You got good advice from the posts below. I went over that process a couple articles back. Get a cartridge case headspace gage and proceed to collect the reading from a fired case, a new case, and then set your sizing die to suit. I suggest between 0.003 and 0.004 for a semi-auto, and 0.001 to 0.002 less for a bolt action.

  4. Thanks, Glen. There’s a lot of good information there. What is your opinion of Small Base sizing dies? How would that compare to David Tubb’s 6XC sizing die? I’ve been using a Redding Small Base die with a bushing for my High Power 223 loads but have been considering trying something else. Any recommendations?
    Thanks Again.

    1. That’s a good question… “We” are starting to seem some merit to reducing the extreme lower portion of the case, the head area, to near to or at new brass dimensions. David is intentionally reducing the sizing another 0.0005, which is not quite as much as most small-base dies would give, but it is more than “standard.” I always use a small-base for my .308 semi-auto loads, but not for the .223s. I’m using a Wylde chamber in my competition .223s and have been satisfied with the performance, and case condition, with my max loads after sizing with a Forster f/l .223 die. I’m using WW brass, for what that’s worth.

  5. If you neck size with a Lee collett neck sizing die you avoid the dreaded doughut… I save time by not lubing and having to remove lube this way Do you see anything wrong with this method?

    1. It’s a worthwhile idea, and I know a lot of folks swear by those dies. FOR A BOLT ACTION! Trick is, that I’ve seen donuts in new cases… The problem might have a few different influences, but in the end it comes from the fairly radical wall thickness variation from shoulder to neck. The flow of the brass will eventually create a donut. The only real solution against the donut is to avoid seating any portion of the bullet into this area. That’s possible in some cartridges with some rifles, but it’s not, for instance, possible in a .223 feeding from a magazine with anything much bigger than a 50 grain bullet. The only other way I’ve found to actually eliminate the donut is either from inside neck reaming (after careful math in setting case neck inside diameter, and also the correct-sized reamer OR turning the case necks, and letting the cutter go down onto the shoulder about a 1/16 inch. That thins the area where the donut flows from. Works. Both these steps are tedious, and a tad amount costly in tooling.

  6. Thanks for the info. I reload 7mm Remington Mag. and the .357 Sig which has been a challenge doing that bottle neck pistol round, crushed quite a few casings! Even tried some 40 S&W resized which worked fine in my Glock 32. Anyways, keep the articles coming, every little bit helps.

  7. I was one of the people who commented on the first installment, not giving you a chance to get deeper into the subject, and not realizing that you were primarily dealing with semi autos first. I whole heartedly agree with your assessment with semi’s. I still (only) neck size for my old friend, the 220 Swift, because it is my only problem child. I have several AR platform rifles (308, 6.5 Grendel, and 223) , all of these are full length sized for feed. I appreciate the tip about the ejector spring.
    Another thing you might discuss, is what happens when a gas operated rifle doesn’t produce enough pressure to operate the key and open the bolt. To the inexperienced, it appears to be too hot, if the bolt doesn’t open, all that pressure has to go somewhere, usually the primer along with case disfigurement that makes it appear to have been too hot. Again, I apologize for jumping the gun, pun intended. I await your next article. Thanks.

    1. Thanks. It’s tough to do a very complete assessment in the short space I have. If there’s not enough pressure, pretty much increase the charge, or change propellants. Contrary to my usual suggestion, might try a tad slower burning propellant. If you’re going for a lighter load with faster propellant, it’s within possibility that could not produce enough gas for the system. The other “solution” is to cut coils from the buffer spring. I’ve had to do that on some Match-style rifles with relocated (forward) gas ports and x-heavy bolt carriers.

  8. I can’t see the difference in the pics of the dials. Only the full length sized case pics have a difference of half a thousandth. I blew them up a few times each…now I have to take advil and tylenol for the headache! I understand what you are saying, just can’t see it in the pics. Good stuff, keep the articles coming!

    1. I can clearly see the difference in the pics. Bear in mind that in the text Glen isn’t talking about a lot of variation, especially in the new cases and the ones that have been resized. Were talking a few thousandths tops but that apparently matters. Great article!

  9. Your articles are extremely informative! I can see that cases will “banana” upon ejection,and need full case sizing. I never thought about it,thanks!

  10. I won’t offer an opinion on the neck only vs full length sizing controversy, but I have to take exception to this statement:

    “It’s not commonly possible to encounter a bolt-action that doesn’t have an ejector”.

    While “push-feed” actions are certainly more common these days, there are LOTS of modern rifles that use “controlled round feed” style actions with no ejector on the bolt face, including: Ruger M77, Winchester 70, CZ 55x, Kimber 8400, Sako 85, Remington 798 and virtually anything with a Mauser style action.

    1. Josh, while you are correct in that the Mauser based actions do not have a button ejector. They do in fact have fixed ejector that is operated when the bolt is pulled back to fixed ejectors position. The fixed ejector runs through a slot in the bolt. The rifles reference with out the ejector are found in long range competition guns where you remove the bolt and cartridge together to manually replace the empty with a loaded round and reinsert the bolt with the ready round back into the rifle. These are usually custom built by design.

      1. Just so you don’t think I’m stupid, haha, I have a hard time getting out of my own realm sometimes, which is competitive shooting. We used to run old-style Win. Model 70s but it’s uncommon to see one anymore. Everyone has gone to a Rem-style bolt, or an AR-platform in NRA High Power.

  11. Awesome article Glen! What are your thoughts on “middle of the road” sizing where the case is neck sized with a bushing, and the shoulder is bumped back .002? I just got the Forster bushing bump die kit and my mind is racing with all the possibilities this die is capable of. I also picked up a copy of a book some dude wrote called Handloading for Competition. Very forward thinking on alot of things. It’s a game changer for me.

    1. I’ve got one of those dies also. My only concern with the neck-bushing-style setup is that the full length of the case neck isn’t sized. That may or may not be a problem, but over time it will have an effect on the case neck size. I like the Neil Jones sizer, if you want to do a mid-road sizing job. His use neck/shoulder combo bushings. They’re kind of pricey, but they work really well. Can control “both ends” of the sizing: more body sizing, move the bushing up; less body sizing move the bushing down. Get neck and shoulder set back same time, either way.

  12. A thought provoking article. What do you think of using the Lee collet die for neck sizing and then using a body die for the rest of the case and to bump shoulders back when the round is tight to chamber?


  13. I have been recommending ‘bumping’ the shoulder .003″ for AR sizing for a long time, partly based on your recommendation I’ve read in some of your AR building guides. Despite the proven improvements in case life, etc., it amazes me how many people simply refuse to follow anything but die makers directions when sizing. Some of them get pretty nasty about it in fact. I haven’t had a case head separation on any caliber for over 30 years, and I believe that is due mostly to bump sizing. Thanks for showing the way to the newbies.

  14. Another factor to consider is that cases will expand away form support. That is, the case expansion and distortion will be away from the supported side. usually the bottom, which is lying against the chamber wall. Thus the case will expand, bulge away form that support. Another reason for a chamber on the small side of the spec. Most semi autos, ARs anyone (?) prefer small dies for reliable function. Usually visual inspection identifies the bulged side and it is marked as the “top” as noted in your article.

  15. Taking full length sizing one step further even. I had a box full of misfired .223 and 5.56 ammo. The majority were very light primer strikes and even restriking them wouldn’t make the round go off. Some were my reloads and some were new manufacture. I also noticed some fired cases would be difficult to get into a Lee Pro 1000 shell plate. They were also impossible to get into a Lee hand held priming tool shell holder. I hung onto all these duds and hard to load empties hoping some day to discover a fix. On a whim I ran a few problematic fired cases through a Lee Bulgebuster rig using a .380 ACP Carbide Factory Crimp die to complete the Bulgebuster. To my surprise the bulgebusted cases went into the Lee primer tool shellholder easily. I hit my misfire drawer and lined up a few of the misfires and noticed 2 things. Several of the misfires, which included mostly factory FC and Lake City ammo, when lined up side by side weren’t standing completely straight. They weren’t off by a lot but 2-3 degrees was visible. I had the same results with the empty cases that I had issues with. Remember I was dealing with new ammo that misfired here. I carefully ran a dozen loaded rounds through the bulgebuster set up and took them to the range. They all fired perfectly. I investigated the remainder of the misfires from my dud drawer and noticed those cartridges, when trying to chamber would go cockeyed in the bolt face turning part of the case head off of the face. The bolt was closing enough to allow the rifle to click but the firing pin just wasn’t reaching the primer hard enough because the cartridge wasn’t sitting flush with the bolt. In total I had over 50 duds saved over the years and after bulge busting each of them they all fired. For whatever reason some cartridge caseheads are not squared with the case and when trying to chamber them the casehead is pulling away from sitting square against the bolt face. I’ve fixed hundreds of fired cases and maybe 75 loaded cartridges and haven’t had any case failures

    1. Smart! Haha. Anyone who’s dealt with as much shooting through M1As with “genuine” match chambers has seen the same sort of thing. I had someone cut off the neck/shoulder area from a small-base die and used it to “fix” cases and loaded rounds as you describe. Some loaded factory “match” ammo would then shoot really well, which is to say “better,” after getting squished about the case head area.

  16. I have been bit a couple of times by loading neck sized ammo into another gun. In is a real pain to get a stuck case out of a chamber. Probably my fault for not marking the ammo for a specific gun. As far as accuracy goes, my Savage 112 will print a .750 group at 400 yards with 75 Amax’s. I have not seen any improvement with neck sized only cases. I am going back to full length sizing to eliminate another day messed up by a stuck case in th wrong gun.

  17. This ejector problem is noticed even in handgun rounds..I run all my handgun brass in a Lee three jaw chuck for case trimming and find a wobble in many cases when running a cordless drill at a good RPM..The higher pressure rounds are worse than say a .45 ACP..Of course all the revolver rounds never show any of that wobble and Now I know why..Thanks for the Info..

  18. Thanks for sharing this great info!
    Does full length sizing ‘RIGHT’ mean having a blueprint of your
    chamber and then building or having built a custom die for your
    Specific chamber?

  19. Also, if answer is yes to above question, who do you recommend
    To do this for me? (There are no smiths in my neck of the woods)

  20. Thanks for article. I never thought about the ejector doing the damage to the brass before. Are there certain bolts that do less damage to the brass?

  21. I have been loading 243 Winchester for two different rifles. My Winchester Model 70 accepts just about anything regardless if I am full leather sizing or not. I recently purchased a Mossberg 243
    For my Grandson. At first I was only neck resizing and I could not use brass that were fired in my Winchester as they were to tight in the Mossberg. I went to full leanth resizing in hopes of being able to shoot all reloads from either rifle. When I did this the mossberg grouping is all over the place. I am now going back to neck sizing and keeping my loads separated in hopes of regaining the accuracy in the mossberg.

  22. Lets face it most of us aren’t Olympic shooters all metal will fatigue with use over time when force is applied. Different brand dies have dimensional differences. Find the right die for your chamber. Overworking the case mouth is fairly common, bevel and chamfering . I prefer a square case mouth burr free. and I take up as much free bore as possible for the rifle. My brass goes back in the case trimmer for every reload not to shorten it but to square the case mouth I have been a machinist for over 30 years I am good with a dozen reloads. I full length size keep in mind when neck sizing one grain of unburnt powder may keep your bolt from closing. We reload for consistent accuracy, premium rounds made by us for us. Our savings is from not buying premium factory ammo, it’s not from using the same brass until it fails. Please don’t use your brass to the point of fatigue. Buy some new brass!

  23. Anything without a spring loaded ejector doesn’t have as much effect. Most modern (new) designs do have spring loaded ejectors. Reducing the pressure on the part helps. Get an extra spring or two in case…

  24. For years I have been a neck sizing only re-loader with my 22-250 cases.
    This article about the banana shaped brass has gotten my attention. DeadeyeA10 posted about a Lee 3-jaw chuck and seeing a wobble. I have one of those but I chuck up a Lee case trimmer holder and used it. I was attempting to “neck turn” my brass and got that dreaded wobble that he got. I then bought that 3-jaw chuck he used and got the same wobble on most cases, although a few were pretty good. I have been getting more technical in my reloads trying for those ” dime-sized one hole”, or smaller at 100 yds. Out of 10 groups, (on average), I have achieved that goal on only 2 out of 10 groups. I have the Forster Bump die and use a Larry Willus digital indicator setup to measure the amount of shoulder “bump” . ( I try for .001 , or .002 max).
    I hope I have not ruined a bunch of cases trying to neck turn.
    I am anxious for it to warm up my old bones so I can enjoy the range again, and see if I found a solution to that only 2 out of 10 groups being decent.

  25. Yes the banana effect is real. If we eliminate the forces applied by the extractor and the ejector springs the case would curl upwards because gravity holds it against the bottom of the chamber. Ideally when firing the case expands and seals the breach or bolt from high pressure gas bypass. The case is going to jump curl and deform every time it’s fired. There are things that we cannot control, minimizing freebore is our best option for accuracy. Some 30mm projectiles ride the lands as much as one and a half times the diameter or more and only the aft portion is full groove size making for a low friction projectile and what happens to the case is irrelevant. An example of that type of bullet is the Remington Golden Saber AKA a rifle rider. Sometimes we trouble ourselves with things that we cannot control to me that’s akin to pouring a bottle of scotch in to the ocean and trying to get it back. If we use the best practices when hand loading and work to improve our shooting skills handloading will always be a rewarding hobby.

    1. I agree completely will hand reloading is the best way for improving the accuracy of the individual in this sense ( if you reload then you probably will try much harder on other aspects – Breath control, trigger control, shooting position ).

  26. Just a thought…On any die, you can cut a paper strip long enough to wrap around one time, then pencil mark and tape it. Remove strip[, lay on flat surface. Determine the left end with a vertical pencil line, same to the right end. Now, looking at the space in between the two lines, using a ruler of sorts, divide this space equally into 23 spaces, separated by a vertical light pencil line. Replace this strip onto your sizing die, with a piece of tape. You now only need to have a reference (I use a piece of bent wire) in between your eye(s) and the die to aid you in changing the amount of “set back” you desire. [ imagine you are looking out a window at a distant object, while holding your index finger up, and you alternately open and close the R/L eye- you notice your finger move ] I use a similar paper strip on my Dillon trimmer to approximate the amount of brass still needed to trim off DURING SET UP. Of course, my dial caliper is ‘on deck’ for exact measure.

  27. The 23 spaces become 23 more lines plus the R & L line to give 25 lines —or about . 055″ 55/1000ths for one complete turn of die. Most dies are 7/8″ x 18tpi. 1/2 turn =.0275″. 1/4 turn moves .013″. 1/8 turn = .006″ . each thread is spaced .055″ apart from the other thread. Each line (twist of die )is approx. .002″ up /down from starting point-reference. This is a quick referencing- USE a dial Caliper.

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