Centrefire Moderator Comparison
We recently embarked on a review of a large cross section of the Centrefire moderators available to the UK market.
The UK is served with a huge number of moderators and the choice can be quite bewildering to anyone entering the market for the first time or looking to change an older model.
Our aim was to conduct a standardised set of tests on all of the sample moderators at the same time, thus removing any variables that may have been involved in producing the individual manufacturers data that accompanies the product marketing.
We had a tremendous response from the UK distributors, many of whom provided moderators to be included on a test and return basis.
The test was carried out using the same rifle (Tikka T3 Lite Stainless .308), same ammunition (PPU 150gr .308), same day/environmentals.
The moderators were measured for:
- Size in mm – actual and forward protrusion from the muzzle
- Weight in grams
- Recoil reduction compared to the same unmoderated rifle and ammunition
- Sound reduction – actual peak dB vs. unmoderated
- Actual Bore size in mm – calculated into radial clearance (space either side of the bullet as it passes through)
- Material/Construction/Resilience to pressure flame erosion/gas cutting.
Peak sound in dB of unmoderated firing was recorded multiple times and an average taken as a base level or control.
Peak Sound of the moderated shots was recorded over a series of shots and an average taken.
Max Sound and Peak sound differ. We chose Peak sound as it is the loudest recorded level of sound without a time constant applied to it.
With a gunshot being over such a short period of time it is more relevant and differs significantly to Max dB
The Peak sound level was recorded using a Brüel & Kjær 2250-S sound analyser mounted on a tripod at a fixed point slightly behind and to the left of the muzzle.
A secondary sound measurement unit was used for back up and comparison.
The B&K 2250 was calibrated at the beginning of the test and control/unmoderated shots were fired before, during and after the moderator tests to confirm recorded measurement levels were accurate and consistent.
The rifle was secured in a test jig which allowed free recoil across the test bench.
Recoil was tested unmoderated and an average was taken for the benchmark.
Recoil reduction was recorded over a series of shots and an average taken.
We also tested a smaller sample of moderators on a range of calibres for difference in sound attenuation compared to radial clearance.
(Does the size of the hole have any bearing on moderated sound levels?)
All data was observed and recorded by an impartial 3rd party (Mr M. Bartlett)
Data analysis and graphics production by Dr. M. Bell (Edinburgh University)
The results are shown in tabular form below and also ranking the top five moderators for each test.
It is important to note that the dB scale is Logarithmic not linear.
103dB is not 3% louder than 100dB.
Every increase of 3 dB represents a doubling of sound intensity, or acoustic power.
Perception of sound is different again.
A 10dB increase is usually perceived as a doubling of loudness.
We used the base dB scale rather than dBA, dBC weighted sound levels as it better represents the peak and full range perceived loudness of low and high frequency sounds.
- Unmoderated shots from .308, .270, .25-06 and 6mmBR all registered within less than 2dB of each other, an average peak of between 165-166.9 dB, despite a powder charge range of 30-60gr
- The first shot(s) from every new unfired moderator was significantly louder than the following shots (so stop cleaning them!!)
- Very few moderators displayed sound attenuation at the levels shown in marketing material.
- Radial Clearance (bore size compared to calibre) was the single most significant factor impacting sound attenuation – the same moderator with a lower radial clearance out-performed the larger bore model by over 6dB reduction
- The heaviest moderators weren’t always the best at reducing recoil.
- The strippable 100% Aluminium Alloy moderators where baffles could be inspected showed signs of flame erosion with only 5-10 shots
- Some moderators are available with additional Stainless Steel baffles to counter erosion, also adding weight. These were not tested.
- Two moderators showed pressure signs with seals/end caps moving or leaking.
- A small sample of moderators were tested on a different rifle/calibre and are shown in a separate sample due to differences in radial clearance. They all outperformed the “In spec” moderators (30cal rating on a 30cal)
- Freyr & Devik Featherweight Titanium (FW196) – 196gr
- DPT Muzzle can (w/o stainless baffle) – 199gr
- MaccTech V2 – 250gr
- Freyr & Devik Featherweight No1 (FW269) – 269gr
- DPT OverBarrel (w/o stainless baffle) – 260gr
Quietest (dB Decibel reduction unmoderated vs. moderated)
- Freyr & Devik Featherweight No1 (FW269) – 27.05 dB
- ASE SL7i – 26.90 dB
- Jet-Z Compact – 26.47 dB
- Freyr & Devik F280 – 26.19 dB
- ASE SL5i – 26.19 dB
Recoil Reduction (mm reduction/percentage reduction- unmoderated vs. moderated
- MAE T12 – 99mm/45%
- Wildcat Predator 12 – 97mm/44.09%
- MAE T12 Scout – 89mm/40.45%
- ASE Northstar – 87mm/39.55%
- MAE MiniT Bushless – 78mm/35.45
Forward Protrusion (mm)
- Freyr & Devik Featherweight Titanium (FW196) – 100mm
- Wildcat Predator 8 – 100mm
- ASE Sl5i – 103mm
- DPT Overbarrel – 105mm
- MAE MiniT/ASE Northstar/Stalon W110 – 110mm
- MAE T12 – 38mm
- MAE T12 Scout – 38mm
- MAE MiniT Bushless – 38.1mm
- Jet-Z – 40mm
- Macc Tech V2 – 41mm
- Aimsport – £210.00
- Wildcat Evolution – £225.00
- DPT Muzzle mounted – £230.00
- ASE NorthStar – £242.00
- Atec Hertz 119 – £246.00
Whether you are looking for the lightest, the quietest, the best recoil reducer or just the cheapest…There are a lot of options out there
- Some will last longer than others under sustained use
- Some are modular and can be tailored or customised to your needs
- Some cover all bases of attenuation, weight and resilience
- Some are clearly more efficient at reducing sound
- All could benefit from closer bore to calibre tolerances.
- Even the most efficient moderator produced a peak sound of over 130dB
Any sound over 85dB can damage your hearing.
Regular exposure to sounds over 110dB risks permanent hearing loss or tinitus
Wear hearing protection!
Huge thanks to Mr. Bartlett and Dr. Bell for their assistance and to all the manufacturers and distributors who provided test moderators
Please contact us to discuss your moderator needs
(click on pictures to enlarge)