PressureTrace

LoadForce-250^™

Neck Tension and Recoil Force Measuring System

The World's First Calibrated Neck Tension and Recoil Meter For Shooters!

Experienced shooters have long understood consistent neck tension is critical to achieving extreme accuracy. Mechanical and electronic devices to measure neck tension have been offered to shooters but they were incapable of measuring the proper forces. Even worse the numbers these devices captured were not calibrated to a standard measure and were not linear (a reading of 100 was not twice the force of 50).

Until now measuring recoil required expensive lab equipment and typical stationery test method employed by most labs produce measurements that are not reflective of the actual recoil "felt" by a shooter. The LoadForce-250 will capture the actual peak force imparted to a shooter's shoulder and when connected to a PC will capture the entire recoil force curve.

New Instrumentation Technology Is The "Key"

New technology called a "compression" gage enclosed in a stainless steel anvil fits any single stage reloading or arbor press for measuring neck tension. When used behind the butt of a rifle in a special "recoil jig", they same sensor can measure recoil.

The LoadForce-250 meter contains a programmed microprocessor to analyze and display data on a 4 line LCD display. A hardware key calibrated for each sensor ensures measurements are fully linear from 0 to 200 pounds of force. Four buttons allow control of various functions and modes.

When connected to a PC using the LF-Scope™ software and cable; a full force curve can be captured.

LoadForce-250 with an arbor press

Measuring Neck Tension

Bullets are started in a conventional way then "finish seated" using the meter. The force required to push the bullet into the neck of each case is automatically displayed on the meter for each round.

The loader then simply sorts rounds as they are loaded according to neck tension. Loads of similar neck tension will always produce more consistent pressures, lower velocity deviation and therefore smaller groups. The meter also helps detect neck rings, rough or dirty necks and other problems that will reduce load performance.

For high volume reloaders it is not necessary to remanufacture loads with higher or lower neck tension. Just box them up and shoot! Each box may "print" in a slightly different location but will be far more consistent then if they contained rounds with "mixed" neck tension.

We've all seen shooters take a piece of brass that tossed a flyer and throw it across the range so they never use it again. Quite often some unprintable expletives accompany the gesture.

Brass does not necessarily "work harden" uniformly ...especially if it has been used to shoot different loads. And, simply keeping track of how many times a piece of brass has been fired will not ensure that all brass in a lot of cases has uniform neck tension.

There is a good probability the discarded brass had work hardened differently or developed roughness due to how it had been cleaned on the inside neck surface. Even chamfering of the mouth can affect neck tension. If the discarded brass were saved, eventually there may be other pieces that produce similar neck tension so it could be used again.

This is why good brass often shoots best when new. Now shooters don't have to discard brass and spend all the time required to sort, turn necks and "uniform" each piece. Providing consistent neck tension can be maintained, brass can often be used until the necks start cracking. Even then, there is always the option of annealing the brass to extend it's life for another cycle.

Varying neck tension changes the shape of the pressure curve and the bullet exit point. The above traces contains 4 shots of a light target load. Enough "fouling" rounds were shot from the cold clean barrel to ensure affects of fouling were not represented in the traces.

This load is normally crimped heavily to achieve acceptable velocities but for this test each was loaded with reasonably differing neck tension. As the neck tension increases the rise time to peak pressure shortens and the bullet exits sooner. Note the Optimum Barrel Timing markers calculated for the rifle by our PressureTrace software. Load T1 exits the barrel at an undesirable time. Indeed, the 4 shot group related closely to this analysis with shot 1 tossing a flyer.

30-06 - Nosler 150gr Ballistic Tip - 50.5gr Varget - WLR primers
Test Shot	LoadForce (lbs)	Velocity (FPS)
T1	70	2762
T2	80	2773
T3	93	2774
T4	112	2795

Measuring Recoil

Shooters have never had an affordable way to measure actual "felt" recoil. There have been many mathematical solutions through the years, but the results are not accurate because the amount of felt recoil is affected by stock design, how it is supported and subjective issues like the shooters weight and build.

To measure recoil with LoadForce the sensor anvil is inserted into a special jig to hold it against the butt of a rifle as it is fired. The actual peak pounds of force is displayed on the meter after each shot. It's that simple!

When connected to a PC with the optional cable and software, LoadForce-250 will capture the entire force curve over time. The following output shows the typical forces produced by rifle recoil against the shoulder of a large person. A spreadsheet and macro provided with the software will also convert the force to energy and allow custom plotting of data.

Why Other Systems Did Not Work Well

Force curve using an arbor press.

We've worked for several years to get this right. We experimented with other systems and determined they all had serious limitations. Both the mechanical and electronic strain gage systems were not calibrated to a standard measure. This alone would not be a major problem, but those other electronic systems were also not linear. A reading of 100 was not twice the force that produced a reading of 50.

To make things worse, both relied on bending metal which would fatigue so readings were not consistent over time. This made it nearly impossible to duplicate load development as the metal parts fatigued.

We were also concerned that readings from other systems often did not correlate closely with group size. After years of research we've isolated the portion of the force curve that most closely correlates to actual neck tension; thereby affecting the pressure curve.

When a bullet is seated, forces first build until static friction is overcome and the bullet starts to move. As it progresses further into the neck, dynamic friction increases as the contact area between the case neck and the bullet increases. When using a standard reloading press, dynamic forces increase until the press reaches the end of its stroke, then force drops off. With an arbor press things are more complex. The in-line die seating stem bottoms out and adds force rapidly as pictured above.

LoadForce-250 captures only forces (in pounds) that correspond to actual neck tension. The meter disregards initial static friction forces and the forces created when an in-line die seating stem bottoms. The pounds of force displayed on the meter when each bullet is seated is the highest dynamic friction detected when the bullet reaches it's final seating depth. Indeed, this force measurement translates most directly to actual neck tension which affects pressure timing.

Each meter contains a Microprocessor and "firmware" that monitors the entire force curve then isolates the correct data. With new compression gage technology there is no fatiguing of bending metal. Each gage is individually calibrated from 0 to 200 pounds to provide many years of repeatable data, in fully linear, pounds of force output.

LoadForce-250 includes:

Meter pictured above with 4 line LCD display, control buttons, download port, external power port and calibration key slot.
Compression sensor with cable enclosed in machined stainless steel anvil with calibration key.
Recoil stand.
CD Rom with LoadForce Manual and LF-Scope program
Low capacitance, robotic application sensor cable.
110v AC or 110/220v AC wall power supply
USB Instrument Adapter
LF-Scope software used to capture full force curve.
- Data is saved in a columnar text format for easy export to a spreadsheet.

World Wide Distributor for LoadForce-250

Recreational Software, Inc.

Software & Instrumentation Technology for the shooting sports.

LoadForce-250™

LoadForce-250^™