## Methods of measuring barrel pressure

Assuming that the weapon is in good condition and that the correct type of ammunition is being used, it is the pressure produced in the barrel which ultimately decides whether the bullet will either reach the muzzle, exit from the barrel at an acceptable velocity or destroy the weapon completely.

Figure 3.1 Pressure barrel.

Often weapons are received with reloaded or home- made ammunition and for safety sake, it is often necessary to determine whether the ammunition is in fact safe to fire. At other times, it is necessary to evaluate the suitability of an ammunition/weapon configuration and once again knowing the barrel pressure produced could be advantageous.

A knowledge of the basic facts concerning how the pressure is measured and what the figures mean is therefore a useful adjunct in this field.

The measurement of maximum chamber pressure is carried out with a 'pressure gun'. This is a very strongly built action and barrel with a hole drilled into the top of the chamber. Clamped over this hole is a closed tube with a free-moving piston (Figure 3.1).

Between this piston and the closed end of the tube is inserted a small disc of metal of a known and uniform hardness. On firing the cartridge, the pressure produced forces the piston up against the metal disc which is crushed against the closed end of the tube. Crushing the metal disc in this way reduces its thickness by a measurable amount. By subjecting similar discs to known pressures, it is possible to calculate the pressure of any cartridge by measuring the compression of the disc.

As no single metal will give consistent results over a wide range of pressures, discs made of lead and copper are used. The lead discs are for lower-pressure cartridges and the copper discs for cartridges producing higher pressures.

As the discs only give accurate pressure figures over the mid part of their range, they cannot be accurately related to actual pressures in pounds per square inch or kilograms per square centimetre. As a result of this, the results are referred to as ' lead or copper units of pressure' .

In more modern pressure guns, the metal disc is replaced by a small quartz crystal. This crystal will, when subjected to pressure, produce a tiny quantity of electricity which can be directly related, with great accuracy, to the pressure exerted upon it. These are called ' piezoelectric' pressure guns. The pressures

 Cartridge Velocity (ft/s) Bullet weight (gr) Pressure (psi) 0.22" LR 1200 40 15 300 0.32" ACP 960 71 21 700 0.38" Special 650 148 21 700 9 mm PB 1200 125 35 500 0.45" ACP 855 234 14 000 5.56 mm M16 3250 56 52 000 12B Shotgun 2.5" Cartridge 1200 490 10 000

measured with these guns are referred to in pounds per square inch or kilograms per square centimetre and are absolute figures (Table 3.1).

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### Responses

• makda
How to measure barrel pressure?
4 years ago
• togo
How to mesure pressure barrel?
4 years ago
• Erik
How do you measure a firearms chamber pressure?
3 years ago
• david
How to produce pressure in the gun barrel?
2 years ago
• pierina
What are the methods in measuring barrel pressure?
2 years ago
• berenice
How cartridge pressure is measured?
2 years ago
• Letteria Lombardi
How bullet pressure is measure?
1 year ago
• zewdi
How is gun barrel pressure measured?
1 year ago
• JOHANNA
How to calculate muzzle pressure?
7 months ago
• Eugenio
HOW TO FIGURE BARREL PRESSURE?
7 months ago
• bellisima
How to calculate barrel pressure?
7 months ago
• brody christie
How to determine muzzle pressure in a firearm?
6 months ago
• Billie
What test pressure from barrel?
5 months ago
• livia
How to calculate barrel pressure shotgun?
4 months ago
• FATIMAH
How to calculate pressures in a cartridge?
4 months ago
• milen
How to measure pressure in a rifle cartridge?
3 months ago
• christine
How to measure pressur inside rifle cartridge?
3 months ago
• heikki
How to check pressure of a rifle?
3 months ago
• merimac
How to measure the pressure of hot gas in a rifle barrel.?
3 months ago
• Enza
How to measure pressure in a mold?
27 days ago
• ROBEL SAARE
Can i measure the pressure inside my guns barrel?
17 days ago