BSA Tune SE and R-10

The RAT WORKS tune varies slightly from model to model in the BSA range, but as a minimum to the work done the tune includes the following: The rifle is stripped down to its component parts; they are inspected for any wear and overall quality. In most cases parts can be machined or replaced if needed and are not charged for.

The rifle is worked through as follows:

Hammer Mechanism
  • Ensure the assembly is free of any oil, grease or debris which can cause consistency issues
  • Replace hammer spring with one of a more efficient design for use in regulated BSA’s
  • Polish the bearing surfaces in the hammer
  • Hammer latch pin modified for use with new banjo pin
  • Fit PTFE slip disks to reduce hammer spring torsion while cocking to aid consistency
  • Custom made hammer weight & guide to minimize hammer noise & decrease strike time
    Generally, to benefit the rifle further the hammer replaced or modified.
Loading assembly
  • Loading probe modified for better airflow, pellet feed and smoothness
  • Bearing surfaces polished
  • On older models the probes are modified to prevent issues when cocking with the modified latch pin
  • Probe guide and pellet tray are modified for a smoother cocking and loading cycle
  • Cocking is modified on early models to remove the need to pull the bolt back further when loading a magazine
  • If you include the magazine in with your rifle they are also modified to remove any loading issues such as jamming whilst cycling
  • The magazine locating pin is modified to give a smoother movement
  • Lubricant is added to parts of the assembly to allow a smoother action
  • Bolt lock up mechanism is modified for more responsive and smoother movement, also increasing the rifles consistency.
  • Bolt flip upon firing is removed or reduced with addition of a new banjo pin
Exhaust valve, transfer port & barrel
  • The exhaust valve stem assembly is modified to run more efficiently
  • Valve is refaced and modified for a faster flow
  • Valve body is modified for better airflow through the firing cycle increasing efficiency
  • The valve pressure is reset to give a better performance between heavy and lighter pellets
  • The transfer port is modified to give more air flow efficiency
  • Breech face modified to reduce wear on the pellet when loading
  • Crown of the barrel re-cut the to increase the rifles accuracy
  • Transfer port and barrel are aligned securely within the assembly
  • Barrel is secured into the breech more accurately and securely than standard
Trigger assembly
  • Sears are polished to a smoother finish
  • Hammer latch pin polished & refaced
    Trigger pin assembly is reinforced to reduce movement from left to right
  • Trigger let-off is set to a comfortable and safe amount.
    1st stage travel can be reduced beyond standard adjustment at request
  • Safety mechanism modified to give an easier movement & reduce noise
Some parts may be chargeable although any damaged parts are generally replaced for free. O-ring seals are replaced as standard throughout the rifle and refitted with the correct lubrication.

Tench Regulator fitting to the BSA Ultra & Scorpion and ‘low breech’ models.

The Tench Regulators were originally designed for these series of rifles, giving excellent shot to shot performance and boosting shot count dramatically, turning rifles that give 30-50 shots a fill as standard into ones that can give 60-100 very consistent and accurate shots.
Tench Regulators add 36mm to the length of the air tube on these rifles, so be aware of this when thinking about fitting a moderator. The older “low breech” BSA Ultra & Hornet rifles do require an adaptor for the fitment of a silencer, for advice on this and solutions please get in touch.

The BSA Hornet is fitted with a BSA regulator as standard; however, these take up nearly 1/3 of the space in the air tube meaning there’s a lot of space available that could be used as an air reservoir. After years of service they are prone to pressure build-up inside the spring chamber of the regulator which can drop the power of the rifle dramatically. Tench Regulators take up less than 1/10 of the space inside the air tube but they do move the air tube forward by 36mm, which can make fitting a silencer difficult, but adaptors are available and the Shotcount improvements on these rifles are massive.

What pressure can I fill to after the Regulator is fitted?

Due to the action of the Tench Regulator on the firing valve, you can now fill your rifle slightly above the manufacturers recommended fill level on most rifles to get the most shot count from them.
When filling any rifle, use the gauge on your bottle or pump to judge how much air is in your gun. The micro button gauges should be used as a guide only.

Tench Regulated BSA fill pressures and shot counts are as follows:

  • BSA Ultra & Scorpion – 250bar

.177 shotcount 55-65 shots
.22 shotcount 70-80 shots

  • BSA Ultra & Scorpion SE – 250 Bar

.177 shotcount 55-65 shots
.22 shotcount 70-80 shots

  • BSA R-10 MK1, 2 & SE – 232bar

.177 Shotcount 180-220 shots
.22 shotcount 190-230 shots

  • BSA Hornet – 250bar
  • .177 Shotcount 90-100 shots
    .22 shotcount 100-110 shots