March 26th, 2016

PMA Micro Die Adjuster — User Reports

PMA Tool Micro Die Adjuster .001 Shoulder Bump full length sizing lift shim

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.

The affordable PMA Micro Die Adjuster is offered in two versions, an upgraded model with a handy thumb screw for $69.95 (photo above), as well as the original with set screw for $65.95 (photo below).

PMA Tool Micro Die Adjuster .001 Shoulder Bump full length sizing lift shim

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

PMA Micro die adjusterProduct 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.

Permalink - Videos, Gear Review, Reloading 4 Comments »
March 26th, 2016

U.S. Supreme Court Confirms Broad Scope of Second Amendment

Second Amendment gun rights supreme court scotus dean weingarten massachusetts stun gun

Commentary by Dean Weingarten, Gun Watch
In an historic, but extremely short unanimous opinion, the United States Supreme Court has confirmed that the Second Amendment applies “to all instruments that constitute bearable arms,”. As this is an enormous class of nearly all weapons, the decision [could be] applied to knives and clubs, and nearly all firearms that have been sold in the United States. Nearly all types of firearms are more common than stun guns. From nbcnews.com:

“But in an unsigned opinion, the U.S. Supreme Court [on 3/21/2016] vacated that ruling. It said the Massachusetts court improperly found that Second Amendment protection applies only to weapons that were in common use at the time of the nation’s founding.”

Referring to its landmark 2008 D.C. v. Heller ruling on handguns in the home, the justices said the Second Amendment applies “to all instruments that constitute bearable arms,” even those not in existence at the time of the founding.

The unsigned opinion is very short[.] Alito writes a much longer and more forceful opinion in concurrence. It could, and should, have gone much further. None the less, it is an enormous win for Second Amendment supporters, and it extends far beyond stun guns and Massachusetts.

There is strong language in this opinion. If 200,000 stun guns in the U.S. are “common”, it is hard to believe that 5 million AR-15s and millions of other semi-automatic rifles are “unusual”.

The case lays to rest the idea that courts can simply say anything other than handguns are “uncommon” or “unusual” and are therefore exempt from Second Amendment protections. This case will be cited far into the future.

The full, unanimous decision, along with Justice Alito’s lengthy concurrence, is found via this LINK:

14-10078 Caetano v. Massachusetts (PDF)

©2016 by Dean Weingarten: Permission to share is granted when this notice and link are included. Link to Gun Watch

(more…)

Permalink Handguns, News 4 Comments »
March 26th, 2016

Defining “Overbore” Cartridges — The Great Debate

What is “Overbore”? That’s a question rifle shooters can debate to no end. This article from our archives proposes one way to identify “overbore cartridges”. We think the approach outlined here is quite useful, but we know that there are other ways to define cartridges with “overbore” properties. Whenever we run this article, it stimulates a healthy debate among our readers — and that is probably a good thing.

Forum Member John L. has been intrigued by the question of “overbore” cartridges. People generally agree that overbore designs can be “barrel burners”, but is there a way to predict barrel life based on how radically a case is “overbore”? John notes that there is no generally accepted definition of “overbore”. Based on analyses of a wide variety of cartridges, John hoped to create a comparative index to determine whether a cartridge is more or less “overbore”. This, in turn, might help us predict barrel life and maybe even predict the cartridge’s accuracy potential.

John tells us: “I have read countless discussions about overbore cartridges for years. There seemed to be some widely accepted, general rules of thumb as to what makes a case ‘overbore’. In the simplest terms, a very big case pushing a relatively small diameter bullet is acknowledged as the classic overbore design. But it’s not just large powder capacity that creates an overbore situation — it is the relationship between powder capacity and barrel bore diameter. Looking at those two factors, we can express the ‘Overbore Index’ as a mathematical formula — the case capacity in grains of water divided by the area (in square inches) of the bore cross-section. This gives us an Index which lets us compare various cartridge designs.”

OVERBORE INDEX Chart

Overbore Index Chart

So what do these numbers mean? John says: “My own conclusion from much reading and analysis is that cartridges with case volume to bore area ratio less than 900 are most likely easy on barrels and those greater than 1000 are hard on barrels.” John acknowledges, however, that these numbers are just for comparison purposes. One can’t simply use the Index number, by itself, to predict barrel life. For example, one cannot conclude that a 600 Index number cartridge will necessarily give twice the barrel life of a 1200 Index cartridge. However, John says, a lower index number “seems to be a good predictor of barrel life”.

John’s system, while not perfect, does give us a benchmark to compare various cartridge designs. If, for example, you’re trying to decide between a 6.5-284 and a 260 Remington, it makes sense to compare the “Overbore Index” number for both cartridges. Then, of course, you have to consider other factors such as powder type, pressure, velocity, bullet weight, and barrel hardness.

Overbore Cases and Accuracy
Barrel life may not be the only thing predicted by the ratio of powder capacity to bore cross-section area. John thinks that if we look at our most accurate cartridges, such as the 6 PPC, and 30 BR, there’s some indication that lower Index numbers are associated with greater inherent accuracy. This is only a theory. John notes: “While I do not have the facilities to validate the hypothesis that the case capacity to bore area ratio is a good predictor of accuracy — along with other well-known factors — it seems to be one important factor.”

Permalink Bullets, Brass, Ammo, Tech Tip 3 Comments »