The document discusses options for reducing recoil in the Barrett Model 82A1/XM107 and XM109 rifles. It identifies four main options: reducing muzzle velocity, increasing recoiling mass, improving muzzle brakes, and modifying the weapon mechanism. Firing from an open bolt is proposed to reduce recoil energy by generating forward momentum, though it may reduce accuracy. Prototype testing will quantify the tradeoff between open and closed bolt firing. The conclusion is that the rifle design allows flexibility to modify performance through simple changes.

1. Recoil Reduction in the Barrett
Model 82A1/XM107 and XM109
Frank Dindl
U.S. Army TACOM-ARDEC
AMSTA-AR-CCL-A; Bldg 7
Picatinny Arsenal, NJ 07806
(973) 724-6761
<fdindl@pica.army.mil>
May 2003
Sergio Aponte
U.S. Army TACOM-ARDEC
AMSTA-AR-CCL-A; Bldg 7
Picatinny Arsenal, NJ 07806
(973) 724-3445
<saponte@pica.army.mil>
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Tank-automotive & Armaments COMmand
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Photo courtesy BarretttoFirearms Manufacturing
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3. Objective:
Discuss options for reducing recoil energy from
firing the Barrett .50 caliber Model 82A1/XM107
and 25mm XM109 rifles.
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4. Background:
The .50 caliber Barrett Model 82A1/XM107 produces modest recoil
energy. The weapon operating mechanism combined with an
efficient muzzle brake reduce recoil energy to about 36 foot-pounds.
The 25mm XM109 fires ammunition with essentially the same
impulse as .50 caliber ammunition. However, the 25mm launches a
much heavier projectile and uses much less propellant. The small
amount of propellant limits the muzzle brake effects. The recoil
energy of the XM109 exceeds 60 foot pounds.
The suppressed version of the Model 82A1/XM107 produces
significantly greater recoil energy than the muzzle brake variant of
the 82A1/XM107, and is also a good candidate for recoil reduction
efforts.
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5. • Several Options For Reducing Recoil
May Be Considered:
Reduce Muzzle Velocity
Increase Recoiling Mass
Increase Muzzle Brake Effects
Modify Weapon Operating Mechanism
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6. • Reduced Muzzle Velocity:
 Reducing the Muzzle Velocity Reduces
the Ammunition Impulse to Produce
Less Recoil Energy
 Trade Off is Reduced Effective Range
• Increased Recoiling Mass:
 Increasing the Recoiling Mass Reduces
the Recoiling Velocity and Produces
Less Recoil Energy
 Trade Off is Increase System Weight
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7. • Increased Muzzle Brake Effects:
 Increasing the Muzzle Brake Effects Reduces the Net
Recoil Impulse and Produces Less Recoil Energy.
• Muzzle brake effects may be increased by
 Increasing the Propellant Charge and Reducing the
Barrel Length to Maintain the Same Muzzle Velocity
While Increasing Propellant Gas Mass and Pressure
Acting on the Muzzle Brake
 Altering the propellant characteristics to increase the
gas pressure at the muzzle
 Improving the efficiency of the muzzle brake
Not an Option for Suppressed Weapon Variants
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8. • Modify the Weapon Mechanism:
 Changing the weapon mechanism to fire from
the open bolt to produce significant forward
momentum at the moment of firing cancels
some of the recoil impulse from firing,
reducing recoil energy.
 Firing in this manner may adversely affect
accuracy, reducing effective range.
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9. “Historically, the most important single
attribute of any military system - whether
it is a rifle, tank, aircraft or ship - is its
capability to be modified and improved to
meet evolving operational requirements.”
Charles Q. Cutshaw, Emergence of the
‘payload rifle’, Jane’s International
Defense Review, August 2002.
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10. Modifications for firing from the open bolt:
Heavier drive spring
Trigger and Sear
Softer barrel bushing
Firing pin sear trip
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16. Prototype testing will measure accuracy and
dispersion firing from the open and closed bolt.
Results will quantify the trade off between firing
from the open bolt and closed bolt, where hit
probability and recoil energy are the key metrics
of interest.
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17. Conclusions:
The Barrett Model 82A1/XM107 and XM109 rifles
offer tremendous flexibility to meet emerging
operational needs. The design of the rifle lends
itself to simple modifications to tailor weapon
performance to meet specific requirements.
May 2003
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