I have tested all the full-bore (Full-bore sound moderators, 24 April 2008) and .22 rimfire moderators on the market (A best-buy guide to sound moderators for .22 rimfires, 31 May 2007), so now I want to look at the .17HMR calibre. It may seem odd to test moderators for only one calibre, but the .17HMR has a unique place in the British vermin shooting sector and deserves to be singled out because it can be tricky to moderate correctly. You can use a full-bore moderator to good effect, but a .22 rimfire moderator can work equally well and will be cheaper. I chose 10 models, some custom made and some newcomers to the market.

Husher 1
The Husher 1 was developed as a non-baffle, low-maintenance .22 rimfi re moderator, which reduces the hot expansion gases from the propellant by swirling them around the outside of the inner cavity and then back on themselves. It costs £127, weighs a mere 238g and is 6in long. Though it offers only moderate noise reduction, it is probably the strongest of the lot.

Whisper
The Whisper was developed as a slimmed-down version of Wildcat’s Predator. It is designed to achieve enough noise reduction to make it viable without adding too much weight. The biggest advantage of the Whisper is that it is
an over-the-barrel design and therefore only extends the muzzle by 4.5in. It is light, being made in aluminium with a stainless steel blast baffle, and it can be stripped easily for cleaning.

SAK
The dimensions and efficiency of the SAK from Jackson rifles make it a natural choice for the .17HMR round. It is 5.8in long, 1.25in wide and light at 165g. Though not the quietest, it does a good job of noise reduction and, being lightweight, stripped down easily. Priced at £33, it is perfect for the non-connoisseur.

PES muzzlecan, rimfire, full-bore
Next are the PES moderators. They are produced by MAE in New Zealand, but are still marketed as PES. The small Parker Hale-type muzzlecan is well made in stainless steel, but its large internal diameter hole makes it less efficient. It can, however, be stripped down, is rust proof and has a small diameter, which blends well with the heavy .17HMR barrels.

The PES/MAE 32mm .17HMR rimfire model is a sealed unit and works efficiently for this size of cartridge. The larger .17HMR baffled 32mm full-bore can is one of the quietest moderators on the market, but you have to pay full-bore prices. However, it is rated for use on all .17 calibre full-bore rifles,
so it can serve a dual role if, say you have a .17 Remington rifle as well.

John Bowkett
John Bowkett offers fine-quality and highly efficient moderators to suit factory and custom-built rifles. The .17HMR version of his rimfire moderator has a superb finish, with 17 baffles and a wide choice of internal chambers
and springs. His moderator was in my top five, which was not really surprising.

Edgar Brothers SM11
The SM11 is the same Sirocco moderator I tested in the .22 rimfire test and is now sold by Edgar Brothers. The company obviously knows a good thing when it sees it, as the SM11 is strippable, lightweight and a good length at 6.8in.

LEI blued and stainless
LEI used to make products only for the military but it now makes civilian sound moderators, which are marketed by Edgar Brothers. LEI have just produced two .17HMR muzzlecans. They are both in stainless steel, one has a stainless finish and the other is blued or blacked. At only 4.8in long and 0.87in wide, and weighing only 170g, the noise reduction is astonishing.
This should come as no surprise as Edgar Brothers are a Nato-rated supplier with a lot of experience. The only drawback is the price of £150, but they are unique and superbly efficient.

ASE Utra
Jackson Rifles import great full-bore muzzlecans. Though commonly used for .22 rimfire rifl es, its ASE Utra dual-cavity all-steel multi-baffled slimline moderator works well on .17HMR rifl es. Its noise reduction is one of the best and the price is good. It is possible to strip it down, but the 45 degree baffle stack is fiddly to reassemble.

Field tests
I tested each moderator in an open field in Scotland with no obstructions that could influence the results of the test. I enlisted three judges to help to find the quietest moderator. I used a 16in CZ .17HMR Varmint rifle. I fired Hornady 17-grain V-Maxes at an average of 2,477fps from the 16in barrel on a cold morning at sea level, and the results were really varied and interesting.

I tested each moderator against a similar sounding one to determine the quieter of the two. Eventually, we found a winner and ranked the others in order of effectiveness. To the naked ear there were four moderators that scored five out of five for noise reduction, but the tonal range varied between them. Edgar Brothers’ SM11 achieved great noise reduction without being too long or too heavy and can easily be stripped for cleaning. At £50 it is very good value for money, too.

The PES 32mm muzzlecan with .17 calibre blast baffle was quieter than the SM11 and its stainless steel construction is a bonus. Though it is long at 7.8in, this was not a problem on a short-barrelled rifle such as the CZ.

The ASE Utra also was very good. At £84, with a slim 1.1in diameter and 6.5in length, it gave very good noise reduction from a small all-steel fully strippable design. This can also be said of John Bowkett’s custom-made unit, which was superbly constructed. It was a good length, gave excellent noise reduction and can also be stripped for cleaning.

The two new LEI models were the most interesting of the top-end moderators. The high quality of performance from such small units was impressive, though sometimes a pop could be heard when the first round was fired as the air in the moderator was consumed by combustion gases. Both moderators were stainless steel and tiny at only 4.8in long and 0.87in diameter. Some people might object to the fact that they can’t be stripped down, especially with a dirty .17HMR round, but tapping them on a hard surface after use will dislodge any dirt. LEI used a professional Brüel & Kjaer sound meter to test its moderators and the company sent some information to me to show how incredibly efficient its moderator is. The LEI has an internal volume of only 46cm³, whereas a Whisper has 174cm³, a SAK 118cm³ and a SM11 110cm³. The noise or decibel reduction readings are as follows: Whisper 23.3dB, SAK 26.9dB, SM11 28.6dB and LEI 27.5dB. In other words, though the LEIs were
not the quietest moderators on test, for their size they are remarkable. The only downside is you have to pay £150.

The remaining moderators reduce the muzzle report of the .17HMR to a more acceptable level and for the majority of shooters who do not want to spend a fortune they will all serve adequately. Priced at £33, the SAK is a no-nonsense cheap and effective .17HMR moderator that will please most shooters.

Conclusion
Using the diminutive .17HMR cartridge made it clear that it is a tricky round to moderate correctly, and the array of moderator designs and sizes
produced some interesting results. Every reader’s rifle will differ, as will their expectations on moderator performance. Therefore, those dB junkies who absolutely have to have the decibel reading will be pleased to hear I plan
to test the 10 best full-bore and rimfire moderators using two different £5,000 meters operated by experts for a definitive moderator test.

The LEI is an efficient performer, but if economy is important then the SM11 with its great noise reduction is a good buy. The PES 32mm muzzle doubles as a full-bore moderator, so it can be used on more than one rifle, the Bowkett offers custom-built quality and the ASE Utra is available straight off
the shelf.

To me, however, it is not only about noise reduction. The rifle has to feel and shoot well, the costs must not be too prohibitive and longevity is also key.

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  • Cameron Fisher

    So for your .17HMR moderator tests, it was the Whisper that was the quietest moderator tested, is that correct?

    Regards Cameron

  • Richard Reeve

    I can’t tell from the conclusion what moderator was the “winner” or see the ranking order of effectiveness?… Bruce I really rate your reviews so can you help me out and clarify this?