Here is a simple, low-cost way to get reliable readings of case headspace when you “bump” the shoulder back on your 6BR, .243 Win, or .308 Win brass. Credit Boyd Allen for this tip. First, you’ll need one .45 acp case, with primer removed. Make sure the .45 acp case is trimmed square and that it is round. We recommend you first run it through an expander, then size it, trim it and chamfer. Next, take the .45 acp case and slip it over the neck of a fired, unsized rifle case with the primer removed. Align the two cases between the jaws of your calipers and note the length from rim to rim (See photo below, with striped case).
OK, now you have the length for a fired rifle case BEFORE sizing. Next, take a full-length sized rifle case (without primer) and do the same thing, placing the .45 acp case over the neck of the FL-sized case (Bottom Photo). The difference between the two numbers is the amount of “bump” or set-back you are applying to the shoulder. Here the difference is .0015″. The amount of bump you need varies with your chamber and your load, but .0015-.002″ is a good initial setting. By using this simple tool, you can avoid bumping the shoulder too much. This will also help you set-up the depth of your full-length die to get the proper amount of bump each time.
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Our friend Erik Cortina is at Raton, NM this week at the F-Class Nationals. When he’s not shooting (or working) Erik produces YouTube videos. One of his most popular videos explained why you should full-length size cartridge brass. In no uncertain terms Erik says: “Quit Neck Sizing!!!” Watch the Video:
Why It’s Smart to Full-Length Size Your Brass
Commentary by Erik Cortina
Should You Full-Length Size Your Cartridge Brass?
Absolutely. Let Me Explain Why…
I have seen it time and time again, shooters on the line wrestling with their rifle trying to get the bolt closed while the wind is switching. They were too focused trying to get their bolt to close and getting their rifle settled back on the bags that they missed the wind switch. Bang… Eight! The straw that broke the camel’s back for me was at the 2017 Canadian Nationals. I was paired up with a young girl and she would try really hard to close the bolt on her rifle. The majority of the time she would get it to close, but often times she could not even get the round to chamber. She was focused on her rifle the entire time rather than on the conditions. When we completed our strings, she had five rounds that did not chamber our of 15! That is way too many!. I told her she needed to think about Full-length sizing with 0.002″ shoulder bump, or Controlled Full-length Sizing like I call it. I told her not to worry about losing accuracy. I told her that I full-length size all my rounds and asked if she noticed how smooth my bolt was and noticed my score. She said yes, they were both great!
Controlled Full-length Sizing Does NOT Harm Accuracy
I have found that Controlled Full-length Sizing does NOT hurt accuracy or shorten brass life. I find that I can focus much more on the conditions when I don’t have to think about chambering a round nor extracting it. It has become second nature. After firing, I keep my head welded to the stock, I open the bolt by placing my thumb on top of stock and rotating hand upwards. I reach in and retrieve spent case, place it back in ammo box, and pick up another loaded round and put in chamber. I verify conditions and when ready, I push the bolt in and close it with my index and middle finger.
With Controlled Full-length Sizing you “bump” the shoulder around .002″ for bolt guns.* Image courtesy Sinclair International which carries a variety of Full-length dies.
Whidden Full-Length Sizing Dies by AccurateShooter.com Editor
For proper Full-length sizing, you want a quality die that’s a very good match to your chamber. For our project rifles we usually turn to Whidden Gunworks which offers both bushing and non-bushing FL dies. And if you want the hot new option, check out Whidden’s patent-pending, click-adjustable FL-sizing die. This gives instant, precise control over shoulder bump. It works great.
*With gas guns, such as the AR10, you may want to increase shoulder bump to .003″ or more. With some benchrest cartridges, .0015″ bump may prove optimal. But .002″ is a good starting point.
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Harrell’s Precision sells “semi-custom” full-length bushing dies for the PPC and 6BR chamberings. While the Harrell brothers do not cut the die to spec, they carry a large selection of dies made with slightly different internal dimensions. When you send in your fired brass, the Harrells choose a die from inventory with just the right amount of sizing (diameter reduction) at the top and bottom of the case. Given the quality, and precise fit, Harrell’s full-length dies are a good value at $75.00 plus shipping.
Bump Measuring Collar
The Harrell brothers provide a nice bonus item with each full-length die — a neat, little shoulder bump measuring device as shown in the photo at right. Hornady/Stoney Point sells a stand-alone tool that does the same job, but the Harrell’s bump collar is simpler and faster. To measure your shoulder bump, simply place the Harrell’s bump collar over the front of your deprimed case (before sizing) and measure the OAL with your calipers. Then size the case in your full-length die, replace the collar and repeat the measurement. You want to set your die so the shoulder moves back about .001″ to .0015″ for most applications. (With semi-auto guns you may want more bump.)
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This article is part of Sinclair Int’l Step-By-Step Reloading Series. Most of the products mentioned in this article are sold through Brownells.com.
by Roy Hill, Brownells/Sinclair Copywriter
Making your own precision handloads is a meticulous journey with many steps, many important matters to consider, and many sets of measurements to calculate. For those who pursue the perfect group, the highest score, the really long accurate shot, the rewards more than outweigh the effort. Choosing the right cases, deburring the flash holes, making the primer pockets uniform, trimming the cases, and lubricating them are all familiar – and critical – steps along the journey. And now that your brass preparation is complete, you are at last ready to start running the cases through your press and fill them with primers, powder, and bullets. The very first die the brass encounters is the sizing die. You insert the case, work the press’s lever to return the case to its correct pre-fired dimensions – and the journey continues.
There are three types of sizing dies to think about: neck, full-length, and small base. All three have specific benefits and potential drawbacks, and you should choose the type of die you use by thinking very carefully about what kind of shooting you plan to do with your handloads. No matter which type you select, most sizing dies will also punch out the old spent primer with some sort of decapper assembly that uses a hardened steel rod. Many types of sizing dies use an expander ball inside the die to make sure the neck of the case will accommodate a bullet after being sized. With some size dies, the expanders are easily removable and interchangeable, letting you get exactly the neck tension you want. If you are reloading for pistol cartridges, carbide sizing dies allow you to quickly resize without applying any lube to the case. But rifle cases always need lube.
Neck-Sizing Dies Neck-sizing dies resize only the neck of the case. The benefit of sizing only the neck is that the brass is “worked” very little, letting you reuse the same cases many times over. Also, cases that have already been fired in your rifle are perfectly fireformed to fit that rifle’s chamber, which can help accuracy. However, neck-sized cases will fit only the specific rifle they were originally fired in, and may still require a little extra force to chamber or extract.
Sinclair recommends that neck-sized-only cartridges should not be used any in other rifle besides the one they were originally fired from [unless they are also FL-sized], or in any action other than a bolt-action. Neck-sized-only rounds are great for the target range or the benchrest but should not be used in critical situations like military or police operations, or hunting. And if you fire them enough times, neck-sized cases will still need to be full-length sized periodically for you to keep using them.
Full-Length Sizing Dies Full-length sizing dies do exactly what their name says: resize the full length of the case, not just the neck. Full-length sizing helps create handloads that will function in any rifle, not just the one from which the cases were originally fired. The potential downside of full-length sizing is that it may shorten case life because it works the brass more than neck sizing. But it’s possible to “tune” today’s full-length sizing dies so they barely work the brass at all, as this article by Sinclair Reloading Tech Ron Dague shows.
Illustration Shows How a Full-Length Sizing Die Works
Another way to reap the benefits of full-length sizing is to use Redding’s full-length bushing dies, which size the full length of the case but use a system of interchangeable bushings that enable you give the case neck the bare minimum of resizing needed. To see how finely adjustable bushing dies are, and how they resize the case while fully supported, CLICK HERE for Video. The neck bushing helps you precisely control the neck tension to help increase the consistency and accuracy of your handloads.
Small Base Dies
A Small Base Die is just another type of full-length sizing die, but one that is typically used when reloading for semi-automatic rifles, like the AR-15, M14, or AR-style .308 rifles. (It may also work well for bolt guns that need extra sizing on the lower section of the case.) A small base die works exactly like a full-length sizing die, only it compresses the brass just a bit more, usually about .001″ more, and may even push the case shoulder back just a hair. Small base dies give that extra bit of compression to the brass to help make sure the case will properly extract from a semi-automatic firearm. The upside is that you get precision handloads that should work flawlessly in your semi-automatic. The downside is case life is really shortened, especially compared to brass used only in one bolt-action rifle, because the brass is worked more.
Shoulder Bump Gauges
A handy tool for setting up your full-length sizing dies as close as possible to your rifle’s chamber is the Sinclair bump gauge. The bump gauge lets you resize the case as little as possible, to extend case life and help your handloads fit your rifle almost like a neck-sized only die. You use deprimed cases fired in your rifle and bump gauge inserts to help you set up the die so it resizes the case only about .001″ to .004″, depending on what type of rifle you’re shooting.
Video shows how to use a shoulder bump gauge to set up your full-length dies
Article Find by EdLongrange. We welcome reader submissions
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When your cases become hard to extract, or you feel a stiff bolt lift when removing a cartridge, it’s probably time to full-length size your cases, and “bump” the shoulder back. With a hunting load, shoulder bumping may only be required every 4-5 loading cycles. Short-range benchrest shooters, running higher pressures, typically full-length size every load cycle, bumping the shoulder .001-.002″. High Power shooters with gas guns generally full-length size every time, and may need to bump the shoulders .003″ or more to ensure reliable feeding and extraction.
Use Shims for Precise Control of Shoulder Bump
Some shooters like to set the “default” position for their full-length die to have an “ample” .003″ or .004″ shoulder bump. When they need less bump, a simple way to reduce the amount of shoulder movement is to use precision shims in .001″ (one-thousandth) increments.
Here are reports from Forum members who use the shims:
“Great product. I have my die lock ring(s) adjusted for the shortest headspace length on my multiple chambers 6BRs and 6PPCs. When needing a longer headspace, I just refer to my notes and add the appropriate shim under the lock ring. Keep it simple.” — F.D. Shuster
Mats Johansson writes: “I’ve been using [shims] since Skip Otto (of BR fame) came out with them. I set up my dies with the .006″ shim, giving me the option of bumping the shoulder a bit more when the brass gets old and hardens while still having room to adjust up for zero headspace, should I have missed the original setup by a thou or two. Hunting rounds can easily be bumped an extra .002-.003″ for positive, no-crush feeding. Being a safety-oriented cheapskate, I couldn’t live without them — they let me reload my cases a gazillion times without dangerous web-stretching. Shims are a must-have, as simple as that.” — Mats Johansson
Sinclair Int’l offers a seven-piece set of Sizing Die Shims that let you adjust the height of your die (and thereby the amount of bump and sizing) in precise .001″ increments. Sinclair explains: “Some handloaders will set their die up to achieve maximum sizing and then progressively use Sinclair Die Shims between the lock ring and the press head to move the die away from the shellholder. Doing this allows you to leave the lock ring in the same position. These shims are usually available in increments of .001″ and work very well.”
Seven Shims from .003″ to .010″
Sinclair’s Die Shim Kit (item 22400) includes seven shims in thicknesses of .003, .004, .005, .006, .007, .008, and .010. For ease of use, shim thickness is indicated by the number of notches cut in the outer edge of each shim. Even without looking you can “count” the notches by feel. Normally priced at $11.99, this shim kit is on sale now for $10.99.
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Wouldn’t it be great if you could quickly and easily adjust shoulder bump during the full-length sizing process, without struggling to move die lock-rings by trial and error (or fiddle with shims). Well you can. The PMA Micro Die Adjuster is a brilliant little device that replaces the lock ring on your FL sizing die. It allows you to move the die up and down in precise, tiny increments. The tool has .001″ index marks, but you can easily set your die between the marks to achieve .0005″ (half-thousandth) adjustments.
To see how the PMA Micro-Die Adjuster works, watch this video by our friend Boyd Allen:
Many of our Forum members now use the PMA Micro Die Adjuster, and they give this specialty tool high praise. Here are actual reviews by Forum members and other verified tool buyers. Read more comments in this AccurateShooter Forum Thread.
PMA Micro Die Adjuster User Reviews
“No more ‘close enough’ for headspace[.] With this tool set-up it’s easy to put headspace exactly where you want it, then repeat it exactly for subsequent batches for the same cartridge.” — JohnF
“I have four of these Micro Adjuster rings and all I can say is that it works and it is repeatable. I bump my brass .0005″-.001″ and this die lock ring will do it without issue.” — TrapperT
“I size brass for four different 6.5×47 rifles (chambered with three different reamers) using a single die, set in the PMA Adjuster. I have to say… I should have bought one sooner. Adjusting it is very quick and repeatable to well under .001.” — /VH
“I’ve been using PMA’s lock ring for some time now and find it to be very easy to adjust to within .0005″ on a single piece of brass. Very quick to do as well. One thing I have found is that if you still need that half-thou adjustment I will run the brass once more at the same setting before I make that .0005″ adjustment and 50 percent of the time that does the trick. The marked increments are in .001″ scale so if you go half way in between there’s your half-thousandth.
PMA Micro-Adjuster vs. Shims
Many hand-loaders have abandoned shims after trying the PMA Micro Die Adjuster:
“Shims [require] you to completely remove the die. That gets old rather quickly after having used the PMA adjustable lock ring.” — Patch 700
“Great product. Shims used to drive me crazy, put a .002 in and get .0035 of change. With this if you want .0015 set it and that’s what you get.” — John B
“I like mine — adjustments are easy and it will adjust very fine. I used to use .001″ shims. Now can adjust my bump as fine as I want.” — Joe139
Product Description from PMA Tool
The PMA Tool Micro Die Adjuster (MDA) replaces your existing lock ring and can be used with nearly any 7/8-14 full length sizing die. We successfully used this tool with sizing dies from Redding, RCBS, Hornady, Lee, Harrells Precision and those made from Newlon Precision die blanks. It allows you to easily make adjustments to your “shoulder bump” as fine as .0005″. The engraved marks on the MDA are equal to approximately .001 inches (true adjustment .000992″) of adjustment to the shoulder bump. Splitting the engraved marks is therefore approximately equal to .0005″. The design of the MDA does not allow it to work with the Forster Co-Ax press. Some custom dies for very short cartridges may require the use of an extended shellholder. Micro Die Adjuster shown in use installed on Custom Newlon/Scott 6mm PPC Die and Harrells Precision Compact Press.
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Sinclair International has a helpful, three-part video series on Full-Length Sizing. The full-length sizing die performs multiple important functions: it resizes the case body, resizes the neck, and adjusts the headspace relative to the chamber (it can also eject the spent primer if that was not done previously).
While neck-sizing-only can work with moderate loads (for a couple firings), after repeated firings the case can stretch, becoming too tight to chamber easily. If you shoot cases with high-pressure, near-max loads, you will probably benefit from full-length sizing your cases each reloading cycle. When full-length sizing, you will want to move the shoulder back (i.e. “bump” the shoulder) to provide proper clearance in the chamber. A case that has grown too much will exhibit stiff bolt lift after firing and be hard to chamber if it is not FL-sized during the reloading process.
Sinclair recommends bumping cases .001-.002″ (one to two thousandths) for cases used in bolt-action target-shooting rifles, or .003-.005″ (three to five thousandths) for hunting rifles or semi-auto rifles. To move the shoulder back you screw the FL-sizing die downwards in the press once you’ve determined “just touching” on the shoulder. You don’t have to screw the die down very far! With a normal 14-pitch die, 1/8th turn (45° rotation) yields approximately 0.009″ of downward movement. So it doesn’t take much to add a few thousandths of bump.
Case Sizing Part One — Why We Full-Length Resize
Case Sizing Part Two — How to Set Up Your Sizing Die
Case Sizing Part Three — How to Use a Bump Gauge
NOTE: These FLASH videos may not display on some mobile devices.
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Wouldn’t it be great if you could quickly and easily adjust shoulder bump during the full-length sizing process, without struggling to move die lock-rings by trial and error (or fiddle with shims). Well you can. The PMA Micro Die Adjuster is a brilliant little device that replaces the lock ring on your FL sizing die. It allows you to move the die up and down in precise, tiny increments. The tool has .001″ index marks, but you can easily set your die between the marks to achieve .0005″ (half-thousandth) adjustments.
To see how the PMA Micro-Die Adjuster works, watch this video by our friend Boyd Allen:
Many of our Forum members now use the PMA Micro Die Adjuster, and they give this specialty tool high praise. Here are actual reviews by Forum members and other verified tool buyers. Read more comments in this AccurateShooter Forum Thread.
PMA Micro Die Adjuster User Reviews
“No more ‘close enough’ for headspace[.] With this tool set-up it’s easy to put headspace exactly where you want it, then repeat it exactly for subsequent batches for the same cartridge.” — JohnF
“I have four of these Micro Adjuster rings and all I can say is that it works and it is repeatable. I bump my brass .0005″-.001″ and this die lock ring will do it without issue.” — TrapperT
“I size brass for four different 6.5×47 rifles (chambered with three different reamers) using a single die, set in the PMA Adjuster. I have to say… I should have bought one sooner. Adjusting it is very quick and repeatable to well under .001.” — /VH
“Great product. Shims used to drive me crazy, put a .002 in and get .0035 of change. With this if you want .0015 set it and that’s what you get.” — John B
“I’ve been using PMA’s lock ring for some time now and find it to be very easy to adjust to within .0005″ on a single piece of brass. Very quick to do as well. One thing I have found is that if you still need that half-thou adjustment I will run the brass once more at the same setting before I make that .0005″ adjustment and 50 percent of the time that does the trick. The marked increments are in .001″ scale so if you go half way in between there’s your half-thousandth.
PMA Micro-Adjuster vs. Shims: With respect to using shims, that requires you to completely remove the die. That gets old rather quickly after having used the PMA adjustable lock ring.” — Patch 700
“I like mine — adjustments are easy and it will adjust very fine. I used to use .001″ shims. Now can adjust my bump as fine as I want.” — Joe139
“The PMA adjuster works just like they say it does and is very simple to use and adjust. I use JLC inserts as well … as nice as they are you’re still hobbled by a click. However with the PMA you can go between what would be clicks. And you can use them … with any die.” — Dusty Stevens
Product Description from PMA Tool
The PMA Tool Micro Die Adjuster (MDA) replaces your existing lock ring and can be used with nearly any 7/8-14 full length sizing die. We successfully used this tool with sizing dies from Redding, RCBS, Hornady, Lee, Harrells Precision and those made from Newlon Precision die blanks. It allows you to easily make adjustments to your “shoulder bump” as fine as .0005″. The engraved marks on the MDA are equal to approximately .001 inches (true adjustment .000992″) of adjustment to the shoulder bump. Splitting the engraved marks is therefore approximately equal to .0005″. The design of the MDA does not allow it to work with the Forster Co-Ax press. Some custom dies for very short cartridges may require the use of an extended shellholder. Micro Die Adjuster shown in use installed on Custom Newlon/Scott 6mm PPC Die and Harrells Precision Compact Press.
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Here is an interesting new measuring device from L.E. Wilson, makers of precision hand dies, case trimmers, and other precision tools. This new Case Gage Depth Micrometer measures shoulder “bump”, so you can determine your headspace both before and after Full-Length sizing. With this Depth Micrometer, you can ascertain exactly how much your FL-sizing die is pushing back the shoulder during the sizing process. While you can measure shoulder setback with comparators on calipers, this Wilson Depth Mic is much more handy. Just place your sized round in the base gage and then slip the micrometer over the top. Take a measurement before FL sizing and then, after sizing, click the micrometer top to verify the amount of shoulder set-back. The measurement is quick and repeatable — very slick.
This is one more nice product from the folks at L.E. Wilson. The $110.00 tool comes with a Gage Block and micrometer top with .001 gradations. The Depth Mic top is compatible with all other Wilson case L.E. Wilson Gages (one size works for all).
Product Tip from EdLongrange. We welcome reader submissions.
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When your cases become hard to extract, or you feel a stiff bolt lift when removing a cartridge, it’s probably time to full-length size your cases, and “bump” the shoulder back. With a hunting load, shoulder bumping may only be required every 4-5 loading cycles. Short-range benchrest shooters, running higher pressures, typically full-length size every load cycle, bumping the shoulder .001-.002″. High Power shooters with gas guns generally full-length size every time, and may need to bump the shoulders .003″ or more to ensure reliable feeding and extraction.
Use Shims for Precise Control of Shoulder Bump
Some shooters like to set the “default” position for their full-length die to have an “ample” .003″ or .004″ shoulder bump. When they need less bump, a simple way to reduce the amount of shoulder movement is to use precision shims in .001″ (one-thousandth) increments.
Here are reports from Forum members who use the shims:
“Great product. I have my die lock ring(s) adjusted for the shortest headspace length on my multiple chambers 6BRs and 6PPCs. When needing a longer headspace, I just refer to my notes and add the appropriate shim under the lock ring. Keep it simple.” — F.D. Shuster
Mats Johansson writes: “I’ve been using [shims] since Skip Otto (of BR fame) came out with them. I set up my dies with the .006″ shim, giving me the option of bumping the shoulder a bit more when the brass gets old and hardens while still having room to adjust up for zero headspace, should I have missed the original setup by a thou or two. Hunting rounds can easily be bumped an extra .002-.003″ for positive, no-crush feeding. Being a safety-oriented cheapskate, I couldn’t live without them — they let me reload my cases a gazillion times without dangerous web-stretching. Shims are a must-have, as simple as that.” — Mats Johansson
Sinclair Int’l offers a seven-piece set of Sizing Die Shims that let you adjust the height of your die (and thereby the amount of bump and sizing) in precise .001″ increments. Sinclair explains: “Some handloaders will set their die up to achieve maximum sizing and then progressively use Sinclair Die Shims between the lock ring and the press head to move the die away from the shellholder. Doing this allows you to leave the lock ring in the same position. These shims are usually available in increments of .001″ and work very well.”
Seven Shims from .003″ to .010″
Sinclair’s $12.49 Die Shim Kit (item 22400) includes seven shims in thicknesses of .003, .004, .005, .006, .007, .008, and .010. For ease of use, shim thickness is indicated by the number of notches cut in the outer edge of each shim. Even without looking you can “count” the notches by feel.
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This article is part of Sinclair Int’l Step-By-Step Reloading Series. Most of the products mentioned in this article are sold through Sinclair’s webstore.
by Roy Hill, Brownells/Sinclair Copywriter
Making your own precision handloads is a meticulous journey with many steps, many important matters to consider, and many sets of measurements to calculate. For those who pursue the perfect group, the highest score, the really long accurate shot, the rewards more than outweigh the effort. Choosing the right cases, deburring the flash holes, making the primer pockets uniform, trimming the cases, and lubricating them are all familiar – and critical – steps along the journey. And now that your brass preparation is complete, you are at last ready to start running the cases through your press and fill them with primers, powder, and bullets. The very first die the brass encounters is the sizing die. You insert the case, work the press’s lever to return the case to its correct pre-fired dimensions – and the journey continues.
Some of our readers have questioned how to set up their body dies or full-length sizing dies. Specifically, AFTER sizing, they wonder how much resistance they should feel when closing their bolt.
Forum member Preacher explains:
“A little resistance is a good, when it’s time for a big hammer it’s bad…. Keep your full-length die set up to just bump the shoulder back when they get a little too tight going into the chamber, and you’ll be good to go.”
To quantify what Preacher says, for starters, we suggest setting your body die, or full-length sizing die, to have .0015″ of “bump”. NOTE: This assumes that your die is a good match to your chamber. If your sizing or body die is too big at the base you could push the shoulder back .003″ and still have “sticky case” syndrome. Also, the .0015″ spec is for bolt guns. For AR15s you need to bump the shoulder of your cases .003″ – .005″, for enhanced reliability. For those who have never worked with a body die, bump die, or Full-length sizing die, to increase bump, you loosen lock-ring and screw the die in further (move die down relative to shell-holder). A small amount (just a few degrees) of die rotation can make a difference. To reduce bump you screw the die out (move die up). Re-set lock-ring to match changes in die up/down position.
That .0015″ is a good starting point, but some shooters prefer to refine this by feel. Forum member Chuckhunter notes: “To get a better feel, remove the firing pin from your bolt. This will give you the actual feel of the case without the resistance of the firing pin spring. I always do this when setting up my FL dies by feel. I lock the die in when there is just the very slightest resistance on the bolt and I mean very slight.” Chino69 concurs: “Remove the firing pin to get the proper feel. With no brass in the chamber, the bolt handle should drop down into its recess from the full-open position. Now insert a piece of fire-formed brass with the primer removed. The bolt handle should go to the mid-closed position, requiring an assist to cam home. Do this several times to familiarize yourself with the feel. This is how you want your dies to size your brass, to achieve minimal headspace and a nearly glove-like fit in your chamber.”
We caution that, no matter how well you have developed a “feel” for bolt-closing resistance, once you’ve worked out your die setting, you should always measure the actual amount of shoulder bump to ensure that you are not pushing the shoulder too far back. This is an important safety check. You can measure this using a comparator that attaches to your caliper jaws, or alternatively, use a sized pistol case with the primer removed. See Poor Man’s Headspace Gauge.
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Bump Measuring Collar
To quantify what Preacher says, for starters, we suggest setting your body die, or full-length sizing die, to have .0015″ of “bump”. NOTE: This assumes that your die is a good match to your chamber. If your sizing or body die is too big at the base you could push the shoulder back .003″ and still have “sticky case” syndrome. Also, the .0015″ spec is for bolt guns. For AR15s you need to bump the shoulder of your cases .003″ – .005″, for enhanced reliability. For those who have never worked with a body die, bump die, or Full-length sizing die, to increase bump, you loosen lock-ring and screw the die in further (move die down relative to shell-holder). A small amount (just a few degrees) of die rotation can make a difference. To reduce bump you screw the die out (move die up). Re-set lock-ring to match changes in die up/down position.
