June 14th, 2019

TECH Tip: How to Reduce Run-Out with Seating Dies

USAMU Hump Day Reloading TIR run-out concentricity seating die stem

Each Wednesday, the U.S. Army Marksmanship Unit publishes a reloading “how-to” article on the USAMU Facebook page. A while back the USAMU’s reloading gurus looked at the subject of cartridge run-out and what can be done to produce straighter ammo. Tasked with producing thousands of rounds of ammo for team members, the USAMU’s reloading staff has developed smart methods for improving concentricity, even with budget=price dies. For other hand-loading tips, visit the USAMU Facebook page.

Minimizing Runout with Standard Seating Dies

This USAMU article explains how to set up standard bullet seating dies dies to minimize Total Indicated Run-out (TIR). The loading process is described using a single-stage press since most handloaders have one. A high-quality run-out gauge is essential for obtaining consistent, accurate results.

Having sized, primed, and charged our brass, the next step is bullet seating. Many approaches are possible; one that works well follows. When setting up a standard seating die, insert a sized, trimmed case into the shellholder and fully raise the press ram. Next, back the seating stem out and screw the die down until the internal crimping shoulder touches the case mouth.

Back the die out ¼ turn from this setting to prevent cartridge crimping. Next, lower the press ram and remove the case. Place a piece of flat steel (or window glass, which is quite flat) on the shellholder and carefully raise the ram.

Place tension on the die bottom with the flat steel on the shellholder. This helps center the die in the press threads. Check this by gently moving the die until it is well-centered. Keeping light tension on the die via the press ram, secure the die lock ring. If one were using a match style, micrometer-type seating die, the next step would be simple: run a charged case with bullet on top into the die and screw the seating stem down to obtain correct cartridge OAL.

However, with standard dies, an additional step can be helpful. When the die has a loosely-threaded seating stem, set the correct seating depth but don’t tighten the stem’s lock nut. Leave a loaded cartridge fully raised into the die to center the seating stem in the die. Then, secure the stem’s lock nut. Next, load sample cartridges and check them to verify good concentricity.

USAMU Hump Day Reloading TIR run-out concentricity seating die stem

One can also experiment with variations such as letting the seating stem float slightly in the die to self-center, while keeping correct OAL. The run-out gauge will show any effects of changes upon concentricity. However, this method has produced excellent, practical results as evidenced by the experiment cited previously. These results (TIR Study 2) will reproduced below for the reader’s convenience.

First, however, let’s examine run-out figures of some factory-loaded match ammunition. This should give readers who are new to TIR gauges some perspective about the TIR ranges one might encounter.

TIR Study 1: 50 rounds Lake City M852 Match 7.62mm
(168 gr. Sierra MatchKings)
0.000” – 0.001” = 2%
0.001” – 0.002” = 30%
0.002” – 0.003” = 16%
0.003” – 0.004” = 22%
0.004” – 0.005” = 14%
0.005” – 0.006” = 14%
0.006” – 0.007” = 0%
0.007” – 0.008” = 2%

TIR Study 2: 50 rounds of .308 match ammo loaded using carefully-adjusted standard dies, vs. 50 using expensive “Match” dies from the same maker.

Standard dies, TIR:
0.000” — 0.001” = 52%;
0.001”– 0.002” = 40%;
0.002”– 0.003” = 8%.
None greater than 0.003”.

Lesser-quality “Match” dies, TIR:
0.000”– 0.001” = 46%;
0.001” — 0.002” = 30%;
0.002” — 0.003” = 20%;
0.003” — 0.004” = 4%.

Note: both samples were loaded using the O-Ring method, i.e. with a rubber O-Ring placed under the locking ring of the Full-length sizing die to allow that die to float.

These tips are intended to help shooters obtain the best results from inexpensive, standard loading dies. Especially when using cases previously fired in a concentric chamber, as was done above, top-quality match dies and brass can easily yield ammo with virtually *no* runout, given careful handloading.

Permalink Bullets, Brass, Ammo, Reloading 2 Comments »
December 11th, 2018

Watch Out for Bullet Nose Contact in Short Seating Stems

Seating Stem Glen Zediker

Clearance Check — Remove the seating stem and drop a bullet into it. The farther down the ogive or nose-cone the step recess grips the bullet, the better. If it’s only pressing down against the bullet tip, a crooked seat is assured, along with inconsistent seating depth. — Glen Zediker

Some folks acquire a new seating die and then are surprised to find their hand-loads show crooked bullets and/or inconsistent seating depth. The problem could be a mis-match between the bullet and the die’s seating stem. In some case, particularly with long, streamlined bullets, the bullet tip can actually touch the bottom inside of the stem. This can cause a variety of problems, as Glen Zediker explains…

Invest in a Good Seating Die
Reloading Tip by Glen Zediker
The bullet seating operation is the “last thing” that happens and it’s also the one thing that can corrupt the care and treatment given to the quality of the loaded round prior. A sleeve-style seater, well-machined, goes a whopping long ways toward preserving alignment, and, therefore, concentricity. Also make sure that the stem in yours comes to rest well down onto the bullet ogive, and, above all else, is not contacting the bullet tip! That will wreck a round.

If you have this problem, you should contact the die maker — some will offer a different seating stem expressly designed for longer, pointier bullets. This “long bullet stem” will normally drop right into your existing die. If you plan to run long, VLD-style bullets you should request the special seating stem right from the get-go.

This tip comes from Glen’s newest book, Top-Grade Ammo, available at Midsouth Shooters Supply.

Permalink Bullets, Brass, Ammo, Reloading 1 Comment »
September 7th, 2018

TIP: Polish Seating Stems to Eliminate Ring Marks on Bullets

Seating Stem Reloading Tip Sierra Bullet .223 Remington compressed loads

Here’s a helpful hint for hand-loaders from Sierra Bullets. While this article focuses on Sierra’s new Tipped Match-King bullets, the recommended solutions apply to other bullet types as well. The article explains how sharp edges on a seating stem can cause a ring to be pressed into the bullet jacket — especially with compressed loads that resist downward bullet movement. Here Sierra technician Rich Machholz diagnoses the problem and provides a solution.

Seating Stem Reloading Tip Sierra Bullet .223 Remington compressed loads

Solutions for Ring Marks Caused by Seating Stems

by Sierra Bullets Ballistic Technician Rich Machholz
Now that the new Tipped MatchKing® (TMK) bullets are being shipped and shooters are putting them to use I have received several calls regarding marking on the bullet ogive from the seating stem.

The cause can be traced to one of several things. In the .223 and especially with the long, 77 grain TMK seated at 2.250” or even 2.260” most loads of Varget® and Reloder® 15 are compressed loads, sometimes heavily compressed. This puts a great deal of pressure on the bullet through the seating stem. The result of all this pressure is a mark of varying depth and appearance on the ogive of the bullet. [Editor: We have seen this issue with a variety of other bullet types/shapes as well, including non-tipped VLDs. The solution is profiling the internal cone of the seating stem to match your bullet shape.]

Some older seating stems might even bear against the tip of the bullet which can make a slight bulge in the jacket just below the junction of the resin tip and the copper jacket in a compressed load. If this is the case there is not a ready fix other than calling the die manufacturer and requesting a new deeper seating stem.

Polish Your Seating Stem to Remove Sharp Internal Edges
If the seating stem is of proper depth the culprit most generally is a thin sharp edge on the inside taper of the seating stem. This is an easy fix that can be accomplished by chucking a spare 77 grain bullet in your drill, coating it with valve grinding compound or even rubbing compound or in a pinch even tooth paste.* Remove the seating stem assembly from the seating die. Turn the drill on and put the seating stem recess over the spinning bullet with the polishing compound to break or smooth the sharp edge that is making the offending mark. This might take more than one application to get the proper polish depending upon what you use, but the more you polish the better the blend of angles which will [ensure the stem matches the bullet contours, not leaving a sharp ring].

If the above is a little more than you care to tackle you might try very fine emery cloth twisted to a point that can be inserted into the mouth to the seating stem and rotated to polish the inside to eliminate any sharp edges that might be present.

Load Advice for 77gr TMKs in the .223 Rem
And last but certainly not least. Actually, even though we don’t say you need additional data for the TMKs, remember you are dealing with heavily-compressed loads in some cases because of the additional bullet length. Due to the additional length of these new bullets and in the interest of gaining some room in the case you might consider trying a slightly faster extruded powder like BenchMark or the 4895s or an even more dense powder like the spherical H335®, CFE223 or TAC. The extra room will allow for trouble free bullet seating also.

Good luck and remember we are no further away than your telephone: 1-800-223-8799.

Sierra Bullets Match-King Reloading Bullet Seating

Permalink Bullets, Brass, Ammo, Reloading, Tech Tip 5 Comments »
June 22nd, 2018

How to Improve Case Concentricity with Standard Seating Dies

USAMU Handloading Hump Day Seating Die Adjustment Stem TIR Concentricity Run-out

Each Wednesday, the U.S. Army Marksmanship Unit publishes a reloading “how-to” article on the USAMU Facebook page. This USAMU “Handloading Hump Day” article, the second in a series on improving concentricity, has many useful tips. If you use standard (non-micrometer) seating dies when loading some cartridge types, this article is worth reading. And visit the USAMU Facebook page next Wednesday for the next installment.

Once again, it’s time for USAMU’s “Handloading Hump-Day!” Last week, we addressed achieving very good loaded-cartridge concentricity (AKA “TIR”, or Total Indicator Runout) using standard, “hunting grade” reloading dies.

We explained how to set up the Full-Length Size die to float slightly when correctly adjusted for desired case headspace. We also cited a study in which this method loaded ammunition straighter than a set of [higher grade] match dies from the same maker. [One of the keys to reducing TIR with both sets of dies was using a rubber O-ring below the locking ring to allow the die to float slightly. READ Full-Length Sizing Die TIP HERE.]

Now, we’ll set up a standard seating die to minimize TIR — the other half of the two-die equation. As before, we’ll use a single-stage press since most new handloaders will have one. A high-quality runout gauge is essential for obtaining consistent, accurate results.

Having sized, primed and charged our brass, the next step is bullet seating. Many approaches are possible; one that works well follows. When setting up a standard seating die, insert a sized, trimmed case into the shell-holder and fully raise the press ram. Next, back the seating stem out and screw the die down until the internal crimping shoulder touches the case mouth.

Back the die out one-quarter turn from this setting to prevent cartridge crimping. Next, lower the press ram and remove the case. Place a piece of flat steel on the shellholder and carefully raise the ram. Place tension on the die bottom with the flat steel on the shellholder. This helps center the die in the press threads. Check this by gently moving the die until it is well-centered. Keeping light tension on the die via the press ram, secure the die lock ring.

USAMU Handloading Hump Day Seating Die Adjustment Stem TIR Concentricity Run-out

If one were using a micrometer-type seating die, the next step would be simple: run a charged case with bullet on top into the die and screw the seating stem down to obtain correct cartridge OAL.

However, with standard dies, an additional step can be helpful. When the die has a loosely-threaded seating stem, set the correct seating depth but don’t tighten the stem’s lock nut. Leave a loaded cartridge fully raised into the die to center the seating stem. Then, secure the stem’s lock nut. Next, load sample cartridges and check them to verify good concentricity.

One can also experiment with variations such as letting the seating stem float slightly in the die to self-center, while keeping correct OAL. The runout gauge will show any effects of changes upon concentricity. However, the first method has produced excellent, practical results as evidenced by the experiment cited previously. These results (TIR Study 2) will reproduced below for the reader’s convenience.

TIR Study 2: Standard vs. Match Seating Dies

50 rds of .308 Match Ammo loaded using carefully-adjusted standard dies, vs. 50 using expensive “Match” dies from the same maker.

Standard dies, TIR:
0.000” — 0.001” = 52%;
0.001”– 0.002” = 40%;
0.002”– 0.003” = 8%. None greater than 0.003”.

“Match” dies, TIR:
0.000”– 0.001” = 46%;
0.001” — 0.002” = 30%;
0.002” — 0.003” = 20%;
0.003” — 0.004” = 4%.

AccurateShooter Comment: This shows that, with careful adjustment, the cheaper, standard dies achieved results that were as good (or better) than the more expensive “Match” Dies.

These tips are intended to help shooters obtain the best results from inexpensive, standard loading dies. Especially when using cases previously fired in a concentric chamber, as was done above, top-quality match dies and brass can easily yield ammo with virtually *no* runout, given careful handloading.

Permalink Reloading, Tech Tip 13 Comments »
October 4th, 2016

Toolmaker’s New Hammer — .284 Win F-Open Rig by Cigarcop

John Perkins 21st Century Shooting Cigarcop F-Open .284 Winchester

Forum member Keith W. (aka “Cigarcop”) is a talented riflesmith whose projects display outstanding finish work and attention to detail. Keith does some of the best bedding work we’ve ever seen. Recently Keith completed a rifle for tool-maker John Perkins, owner of 21st Century Shooting. John, who recently competed at the F-Class Nationals in Lodi, WI, wanted a new F-Open rifle with top-of-the-line hardware and a sweet-tracking stock. We think John will be impressed with this gun — and we bet it proves to be an tack-driving “hammer”. John will use the 21.5-lb rifle for F-Open competition and some mid-range and long-range benchrest competition in HG class.

This stock sports 12 coats of Urethane, wet-sanded between each coat.
John Perkins 21st Century Shooting Cigarcop F-Open .284 Winchester

This competition rifle features a melonited BAT “M” action (with Bix’N Andy trigger), a pair of 7mm Brux barrels chambered in .284 Win, and a Precision Rifle & Tool (PRT) Low-Boy stock. As you can see from these photos Keith posted in our Shooters’ Forum, this is a beautifully-finished rifle. If you have questions about this project, direct them to Cigarcop in this FORUM Thread.

Build Details for a Beautiful F-Open Rig
Keith reports: “The rifle is built on a PRT Laminated Low-Boy F-Class Stock with a Bat M Melonited Action, +20 MOA rail, Pillar bedded in Devcon 10110. After bedding and inletting I clear-coated the stock with 12 Coats of a 3-part Urethane finish which was wet-sanded between each coat and sanded out to 2000 before final polishing. John Perkins provided two Brux 1:9″-twist, 1.250″-contour barrels. They are both finished at 31″ and chambered in straight .284 Win with .313″ neck and .213″ freebore to shoot the 180gr Berger Hybrids.

Cigarcop does superb bedding work, as you can see…
John Perkins 21st Century Shooting Cigarcop F-Open .284 Winchester

John chose the Bix’N Andy trigger after sampling one of Erik Cortina’s rifles at the Berger SW Nationals. “I tried the BNA trigger on Erik’s gun and I was so impressed. It is very light but 100% consistent. After an injury I’ve lost some feel in my trigger finger and the BNA helps because it is so smooth. I would never go back to anything else.”

John Perkins 21st Century Shooting Cigarcop F-Open .284 Winchester

New Seating Die from 21st Century
While talking about his new rifle, John Perkins revealed that he has developed a very sophisticated new micrometer seating die: “This is something very new, and unlike anything else on the market. Each die is tailored to the dimensions and ogive curve of your particular bullet which we measure with an optical comparator. The customer provides fired, sized brass and sample bullets and we can produce a perfect match.”

John says his new seating dies produce ultra-consistent base-to-ogive load lengths along with exceptionally low run-out. “This new die produces incredibly straight ammo — there are some special features inside the die that help straighten the bullet during the seating process”. That delivers “truly superior concentricity” according to John. 21st Century Shooting will be taking orders soon for the new seating die. Call (260) 273-9909 for more information.

Permalink Competition, Gunsmithing 2 Comments »
September 19th, 2014

Tech Tip: Try Rotating Cartridge During Bullet Seating Process — This Might Reduce Bullet Run-Out

Redding Competition DieHere is a simple technique that can potentially help you load straighter ammo, with less run-out. It costs nothing and adds only a few seconds to the time needed to load a cartridge. Next time you’re loading ammo with a threaded (screw-in) seating die, try seating the bullet in two stages. Run the cartridge up in the seating die just enough to seat the bullet half way. Then lower the cartridge and rotate it 180° in the shell-holder. Now raise the cartridge up into the die again and finish seating the bullet.

Steve, aka “Short Range”, one of our Forum members, recently inquired about run-out apparently caused by his bullet-seating process. Steve’s 30BR cases were coming out of his neck-sizer with good concentricity, but the run-out nearly doubled after he seated the bullets. At the suggestion of other Forum members, Steve tried the process of rotating his cartridge while seating his bullet. Steve then measured run-out on his loaded rounds. To his surprise there was a noticeable reduction in run-out on the cases which had been rotated during seating. Steve explains: “For the rounds that I loaded yesterday, I seated the bullet half-way, and turned the round 180 degrees, and finished seating the bullet. That reduced the bullet runout by almost half on most rounds compared to the measurements from the first test.”

run-out bullet

run-out bullet

Steve recorded run-out measurements on his 30BR brass using both the conventional (one-pass) seating procedure, as well as the two-stage (with 180° rotation) method. Steve’s measurements are collected in the two charts above. As you can see, the run-out was less for the rounds which were rotated during seating. Note, the change is pretty small (less than .001″ on average), but every little bit helps in the accuracy game. If you use a threaded (screw-in) seating die, you might try this two-stage bullet-seating method. Rotating your case in the middle of the seating process won’t cost you a penny, and it just might produce straighter ammo (nothing is guaranteed). If you do NOT see any improvement on the target, you can always go back to seating your bullets in one pass. READ Forum Thread….

Permalink Bullets, Brass, Ammo, Reloading 14 Comments »