Prasa arborowa hydrauliczna 21st Century 160 psi Hydro Bullet Seater with 308 Loading Block

The fight for uniform neck tension

Ask any precision target shooter for a list of the most important variables to control when reloading and you will find that neck tension is almost always in the top three.  Neck tension refers to the mechanical grip applied to the bullet by the case neck.  When a firearm is discharged, the internal case pressure will build until it is sufficient to overcome this mechanical force and cause the neck to release the bullet. The amount of pressure required to move the bullet out of the case neck is directly dependent on neck tension. A cartridge with greater neck tension will experience a higher spike in chamber pressure when the round is discharged than a cartridge with lower neck tension.  Cartridges with inconsistent neck tension will therefore have variable muzzle velocity and create shot groups that have greater vertical displacement, a phenomenon called “vertical stringing.” Furthermore, a cartridge with greater neck tension will release the bullet somewhat later during the firing sequence than a cartridge with lower neck tension, affecting timing. Neck tension must therefore be carefully controlled in order to obtain tight groupings.

Neck thickness and uniformity, hardness of the brass, and the internal diameter of the neck prior to bullet seating all directly impact neck tension.  Unfortunately, with the possible exception of inside and outside neck diameter, none of these attributes are easy to measure.  Some shooters will measure the change in outside neck diameter that occurs when a bullet is seated, but this fails to take into account the effects of neck uniformity and hardness.  The only course of action left to shooters is to obtain uniformity in the aforementioned variables and hope for the best.  And while annealing cases and neck turning go a long way towards controlling neck tension, these methods aren’t perfect.  Even carefully prepared cases will still have some variation in neck tension for which must be accounted for if we are going to maximize the accuracy of our load.

Quantitative vs qualitative measurement

Although we cannot directly measure neck tension on a loaded bullet, we can directly observe its effects. If neck tension resists the release of a bullet, it also resists the seating of a bullet.  By measuring and recording how much force is required to seat a bullet in each case neck, we can determine how best to sort our rounds. Seating force depends somewhat on the cartridge type, but anywhere from 30-50 psi is normal.  Some shooters will attempt to discern variation in seating force (and through the resistive feedback felt when seating bullets with a press), but this type of qualitative measurement is imprecise and unreliable.  We’ve found that differences in seating force up to 20psi cannot be properly discerned in most instances, leaving substantial room for error.  Undoubtedly, a quantitative, numerical measurement is needed if one is to faithfully sort by neck tension.

Enter the Hydro Press

Our Hydro Press is the much needed answer to this problem.  We have incorporated a hydraulic gauge into a direct leverage press designed to work with chamber dies.  The gauge measures the amount of seating force in pounds per square inch.  When used properly, it allows the hand loader to accurately measure the force required to seat the bullet.  Rounds can then be sorted into groups based on neck tension.

Mechanical gear linkages are popular in modern presses, but these actions are rougher and more susceptible to wear and dirt.  Instead, our press features a consistent, smooth and robust direct leverage action.  Crafted out of stainless steel bar stock and billet aluminum, the action on our hydro press is sturdy and designed to last.

The height of the press is adjustable to accommodate different case lengths.  Our extended base model does not need to be mounted to a bench, enabling you to save space on your bench or to take the press with you to the range. This extended base comes with an interchangeable loading block that holds 25 rounds.  This base and extra loading blocks can also be purchased separately.  The standard short base model requires mounting for proper operation.   The countersunk holes drilled into the base allow you to easily mount the press on your loading bench.

Choosing the Correct Gauge

The 21st Century Innovation Hydro Press is available with three gauges with different maximum PSI capabilities, the 100lb, 160lb, and 200lb models.   The 100lb. model is a good choice if you are loading mostly standard cartridges with light to moderate neck tension (.001-.002").  The 160lb model is a great all-round choice for those working with both standard and magnum cartridges where you may have a bit more neck tension (over .002").  This is a great choice if you are both a target shooter and hunter where you may work with higher neck tensions.  The 200lb model is primarily meant for those working with large caliber magnum cartridges up to the such as those used in ELR competition. (50 BMG, 416 Barrett, Cheytacs, etc,)

NOTE: The oil in the gauge is not connected to the Hydro Press unit. - oil in the gauge is not all the way full.

Please exercise the unit, put a solid die under the ram, ram it up to 20lbs - 40lbs - 60lbs etc. do this for 30 sec.