Most accurate standard sizing die concentricity

The Hornady gauge is for straightening/reducing neck runout on lower quality brass with unequal neck thickness.

This is one of the most accurate bullet seaters ever made.

Seating depth adjustments are made by turning the screw inside the cap (3/8ths - 24 threads). With 'both' gauges above you will be able to sort your cases and setup your dies with the minimum of induced error from the expander button, seating dies etc.Д«elow is my RCBS case mastering gauge and my Hornady concentricity gauge, the RCBS gauge is the Swiss Army Knife of gauges and had to be modified to get accurate runout readings and why I recommend the Sinclair gauge. This style of bullet seater works more accurately than a conventional (7/8'-14) bullet seating die. With normal small variations in case thickness this isn't a problem and will depend on the quality of the brass. We believe the Sinclair Concentricity Gauge is the easiest to use and most accurate gauge of its kind on the market. I use a Redding neck thickness gauge to check the necks and would recommend the Sinclair concentricity gauge for measuring runout.ДЄ cartridge case with unequal case wall and neck thickness will expand more on the thin side of the case and warp and become banana shaped when fired. SINCLAIR INTERNATIONAL SINCLAIR CONCENTRICITY GAUGE. One of the main causes of neck runout is locking down the decapping rod/expander button off center during die setup, the next cause would be unequal neck thickness. This vid explains the accuracy one product quite well. Reloaded for many years without one, but it depends on the goals for your ammunition. If the problem is in the sizing it wont matter a toss what seating die you have. Eccentricity usually starts with case sizing. If your sizing die does not produce relatively straight sized brass, it will have to be replaced, or modified. It is not the expander that is the problem, but rather the ID of the neck part of the die.

This is not to say that one should not aim for zero eccentricity, but if you can maintain readings of. One piece sizing dies that over size the neck causing excessive pull as the expander is pulled through are to be avoided at all cost. You can also check consistency in your equipment and reloading procedure with it to some degree, and it will tell you if something is off, and how change in equipment and technique affect your result. It takes more eccentricity than most would think to be a problem. How important it is to have one is up to yourself to decide, it's a tool i won't reload without anymore but each to they're own. I have both of these and a Hornady gauge, and the accuracy one is my favorite by far. The 21stcentury gauge is also nice, more convenient for measuring ID runout of your necks, but else the accuracy one gauge is the top of the heap. If you want a concentricity gauge, and don't mind paying for it the AccuracyOne gauge is the best there is imo.Д« sells them with a Mitutoyo indicator for 400$ so not cheap.Д«ut for ease of use and consistent reading it can't be beat from my experience, the wheel turn makes it very easy to get consistent results, so no more fiddling with your fingers to apply the right amount of pressure while turning the case.And no more irradical movement of your dial when turning.

Most accurate standard sizing die concentricity